diff options
Diffstat (limited to 'vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr')
4 files changed, 2654 insertions, 0 deletions
diff --git a/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/libotr_test_helper.c b/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/libotr_test_helper.c new file mode 100644 index 000000000..b3ca072d4 --- /dev/null +++ b/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/libotr_test_helper.c @@ -0,0 +1,197 @@ +// Copyright 2012 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// This code can be compiled and used to test the otr package against libotr. +// See otr_test.go. + +// +build ignore + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> + +#include <proto.h> +#include <message.h> +#include <privkey.h> + +static int g_session_established = 0; + +OtrlPolicy policy(void *opdata, ConnContext *context) { + return OTRL_POLICY_ALWAYS; +} + +int is_logged_in(void *opdata, const char *accountname, const char *protocol, + const char *recipient) { + return 1; +} + +void inject_message(void *opdata, const char *accountname, const char *protocol, + const char *recipient, const char *message) { + printf("%s\n", message); + fflush(stdout); + fprintf(stderr, "libotr helper sent: %s\n", message); +} + +void update_context_list(void *opdata) {} + +void new_fingerprint(void *opdata, OtrlUserState us, const char *accountname, + const char *protocol, const char *username, + unsigned char fingerprint[20]) { + fprintf(stderr, "NEW FINGERPRINT\n"); + g_session_established = 1; +} + +void write_fingerprints(void *opdata) {} + +void gone_secure(void *opdata, ConnContext *context) {} + +void gone_insecure(void *opdata, ConnContext *context) {} + +void still_secure(void *opdata, ConnContext *context, int is_reply) {} + +int max_message_size(void *opdata, ConnContext *context) { return 99999; } + +const char *account_name(void *opdata, const char *account, + const char *protocol) { + return "ACCOUNT"; +} + +void account_name_free(void *opdata, const char *account_name) {} + +const char *error_message(void *opdata, ConnContext *context, + OtrlErrorCode err_code) { + return "ERR"; +} + +void error_message_free(void *opdata, const char *msg) {} + +void resent_msg_prefix_free(void *opdata, const char *prefix) {} + +void handle_smp_event(void *opdata, OtrlSMPEvent smp_event, + ConnContext *context, unsigned short progress_event, + char *question) {} + +void handle_msg_event(void *opdata, OtrlMessageEvent msg_event, + ConnContext *context, const char *message, + gcry_error_t err) { + fprintf(stderr, "msg event: %d %s\n", msg_event, message); +} + +OtrlMessageAppOps uiops = { + policy, + NULL, + is_logged_in, + inject_message, + update_context_list, + new_fingerprint, + write_fingerprints, + gone_secure, + gone_insecure, + still_secure, + max_message_size, + account_name, + account_name_free, + NULL, /* received_symkey */ + error_message, + error_message_free, + NULL, /* resent_msg_prefix */ + resent_msg_prefix_free, + handle_smp_event, + handle_msg_event, + NULL /* create_instag */, + NULL /* convert_msg */, + NULL /* convert_free */, + NULL /* timer_control */, +}; + +static const char kPrivateKeyData[] = + "(privkeys (account (name \"account\") (protocol proto) (private-key (dsa " + "(p " + "#00FC07ABCF0DC916AFF6E9AE47BEF60C7AB9B4D6B2469E436630E36F8A489BE812486A09F" + "30B71224508654940A835301ACC525A4FF133FC152CC53DCC59D65C30A54F1993FE13FE63E" + "5823D4C746DB21B90F9B9C00B49EC7404AB1D929BA7FBA12F2E45C6E0A651689750E8528AB" + "8C031D3561FECEE72EBB4A090D450A9B7A857#) (q " + "#00997BD266EF7B1F60A5C23F3A741F2AEFD07A2081#) (g " + "#535E360E8A95EBA46A4F7DE50AD6E9B2A6DB785A66B64EB9F20338D2A3E8FB0E94725848F" + "1AA6CC567CB83A1CC517EC806F2E92EAE71457E80B2210A189B91250779434B41FC8A8873F" + "6DB94BEA7D177F5D59E7E114EE10A49CFD9CEF88AE43387023B672927BA74B04EB6BBB5E57" + "597766A2F9CE3857D7ACE3E1E3BC1FC6F26#) (y " + "#0AC8670AD767D7A8D9D14CC1AC6744CD7D76F993B77FFD9E39DF01E5A6536EF65E775FCEF" + "2A983E2A19BD6415500F6979715D9FD1257E1FE2B6F5E1E74B333079E7C880D39868462A93" + "454B41877BE62E5EF0A041C2EE9C9E76BD1E12AE25D9628DECB097025DD625EF49C3258A1A" + "3C0FF501E3DC673B76D7BABF349009B6ECF#) (x " + "#14D0345A3562C480A039E3C72764F72D79043216#)))))\n"; + +int main() { + OTRL_INIT; + + // We have to write the private key information to a file because the libotr + // API demands a filename to read from. + const char *tmpdir = "/tmp"; + if (getenv("TMP")) { + tmpdir = getenv("TMP"); + } + + char private_key_file[256]; + snprintf(private_key_file, sizeof(private_key_file), + "%s/libotr_test_helper_privatekeys-XXXXXX", tmpdir); + int fd = mkstemp(private_key_file); + if (fd == -1) { + perror("creating temp file"); + } + write(fd, kPrivateKeyData, sizeof(kPrivateKeyData) - 1); + close(fd); + + OtrlUserState userstate = otrl_userstate_create(); + otrl_privkey_read(userstate, private_key_file); + unlink(private_key_file); + + fprintf(stderr, "libotr helper started\n"); + + char buf[4096]; + + for (;;) { + char *message = fgets(buf, sizeof(buf), stdin); + if (strlen(message) == 0) { + break; + } + message[strlen(message) - 1] = 0; + fprintf(stderr, "libotr helper got: %s\n", message); + + char *newmessage = NULL; + OtrlTLV *tlvs; + int ignore_message = otrl_message_receiving( + userstate, &uiops, NULL, "account", "proto", "peer", message, + &newmessage, &tlvs, NULL, NULL, NULL); + if (tlvs) { + otrl_tlv_free(tlvs); + } + + if (newmessage != NULL) { + fprintf(stderr, "libotr got: %s\n", newmessage); + otrl_message_free(newmessage); + + gcry_error_t err; + char *newmessage = NULL; + + err = otrl_message_sending(userstate, &uiops, NULL, "account", "proto", + "peer", 0, "test message", NULL, &newmessage, + OTRL_FRAGMENT_SEND_SKIP, NULL, NULL, NULL); + if (newmessage == NULL) { + fprintf(stderr, "libotr didn't encrypt message\n"); + return 1; + } + write(1, newmessage, strlen(newmessage)); + write(1, "\n", 1); + fprintf(stderr, "libotr sent: %s\n", newmessage); + otrl_message_free(newmessage); + + g_session_established = 0; + write(1, "?OTRv2?\n", 8); + fprintf(stderr, "libotr sent: ?OTRv2\n"); + } + } + + return 0; +} diff --git a/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/otr.go b/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/otr.go new file mode 100644 index 000000000..173b753db --- /dev/null +++ b/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/otr.go @@ -0,0 +1,1415 @@ +// Copyright 2012 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package otr implements the Off The Record protocol as specified in +// http://www.cypherpunks.ca/otr/Protocol-v2-3.1.0.html +package otr // import "golang.org/x/crypto/otr" + +import ( + "bytes" + "crypto/aes" + "crypto/cipher" + "crypto/dsa" + "crypto/hmac" + "crypto/rand" + "crypto/sha1" + "crypto/sha256" + "crypto/subtle" + "encoding/base64" + "encoding/hex" + "errors" + "hash" + "io" + "math/big" + "strconv" +) + +// SecurityChange describes a change in the security state of a Conversation. +type SecurityChange int + +const ( + NoChange SecurityChange = iota + // NewKeys indicates that a key exchange has completed. This occurs + // when a conversation first becomes encrypted, and when the keys are + // renegotiated within an encrypted conversation. + NewKeys + // SMPSecretNeeded indicates that the peer has started an + // authentication and that we need to supply a secret. Call SMPQuestion + // to get the optional, human readable challenge and then Authenticate + // to supply the matching secret. + SMPSecretNeeded + // SMPComplete indicates that an authentication completed. The identity + // of the peer has now been confirmed. + SMPComplete + // SMPFailed indicates that an authentication failed. + SMPFailed + // ConversationEnded indicates that the peer ended the secure + // conversation. + ConversationEnded +) + +// QueryMessage can be sent to a peer to start an OTR conversation. +var QueryMessage = "?OTRv2?" + +// ErrorPrefix can be used to make an OTR error by appending an error message +// to it. +var ErrorPrefix = "?OTR Error:" + +var ( + fragmentPartSeparator = []byte(",") + fragmentPrefix = []byte("?OTR,") + msgPrefix = []byte("?OTR:") + queryMarker = []byte("?OTR") +) + +// isQuery attempts to parse an OTR query from msg and returns the greatest +// common version, or 0 if msg is not an OTR query. +func isQuery(msg []byte) (greatestCommonVersion int) { + pos := bytes.Index(msg, queryMarker) + if pos == -1 { + return 0 + } + for i, c := range msg[pos+len(queryMarker):] { + if i == 0 { + if c == '?' { + // Indicates support for version 1, but we don't + // implement that. + continue + } + + if c != 'v' { + // Invalid message + return 0 + } + + continue + } + + if c == '?' { + // End of message + return + } + + if c == ' ' || c == '\t' { + // Probably an invalid message + return 0 + } + + if c == '2' { + greatestCommonVersion = 2 + } + } + + return 0 +} + +const ( + statePlaintext = iota + stateEncrypted + stateFinished +) + +const ( + authStateNone = iota + authStateAwaitingDHKey + authStateAwaitingRevealSig + authStateAwaitingSig +) + +const ( + msgTypeDHCommit = 2 + msgTypeData = 3 + msgTypeDHKey = 10 + msgTypeRevealSig = 17 + msgTypeSig = 18 +) + +const ( + // If the requested fragment size is less than this, it will be ignored. + minFragmentSize = 18 + // Messages are padded to a multiple of this number of bytes. + paddingGranularity = 256 + // The number of bytes in a Diffie-Hellman private value (320-bits). + dhPrivateBytes = 40 + // The number of bytes needed to represent an element of the DSA + // subgroup (160-bits). + dsaSubgroupBytes = 20 + // The number of bytes of the MAC that are sent on the wire (160-bits). + macPrefixBytes = 20 +) + +// These are the global, common group parameters for OTR. +var ( + p *big.Int // group prime + g *big.Int // group generator + q *big.Int // group order + pMinus2 *big.Int +) + +func init() { + p, _ = new(big.Int).SetString("FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3DC2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F83655D23DCA3AD961C62F356208552BB9ED529077096966D670C354E4ABC9804F1746C08CA237327FFFFFFFFFFFFFFFF", 16) + q, _ = new(big.Int).SetString("7FFFFFFFFFFFFFFFE487ED5110B4611A62633145C06E0E68948127044533E63A0105DF531D89CD9128A5043CC71A026EF7CA8CD9E69D218D98158536F92F8A1BA7F09AB6B6A8E122F242DABB312F3F637A262174D31BF6B585FFAE5B7A035BF6F71C35FDAD44CFD2D74F9208BE258FF324943328F6722D9EE1003E5C50B1DF82CC6D241B0E2AE9CD348B1FD47E9267AFC1B2AE91EE51D6CB0E3179AB1042A95DCF6A9483B84B4B36B3861AA7255E4C0278BA36046511B993FFFFFFFFFFFFFFFF", 16) + g = new(big.Int).SetInt64(2) + pMinus2 = new(big.Int).Sub(p, g) +} + +// Conversation represents a relation with a peer. The zero value is a valid +// Conversation, although PrivateKey must be set. +// +// When communicating with a peer, all inbound messages should be passed to +// Conversation.Receive and all outbound messages to Conversation.Send. The +// Conversation will take care of maintaining the encryption state and +// negotiating encryption as needed. +type Conversation struct { + // PrivateKey contains the private key to use to sign key exchanges. + PrivateKey *PrivateKey + + // Rand can be set to override the entropy source. Otherwise, + // crypto/rand will be used. + Rand io.Reader + // If FragmentSize is set, all messages produced by Receive and Send + // will be fragmented into messages of, at most, this number of bytes. + FragmentSize int + + // Once Receive has returned NewKeys once, the following fields are + // valid. + SSID [8]byte + TheirPublicKey PublicKey + + state, authState int + + r [16]byte + x, y *big.Int + gx, gy *big.Int + gxBytes []byte + digest [sha256.Size]byte + + revealKeys, sigKeys akeKeys + + myKeyId uint32 + myCurrentDHPub *big.Int + myCurrentDHPriv *big.Int + myLastDHPub *big.Int + myLastDHPriv *big.Int + + theirKeyId uint32 + theirCurrentDHPub *big.Int + theirLastDHPub *big.Int + + keySlots [4]keySlot + + myCounter [8]byte + theirLastCtr [8]byte + oldMACs []byte + + k, n int // fragment state + frag []byte + + smp smpState +} + +// A keySlot contains key material for a specific (their keyid, my keyid) pair. +type keySlot struct { + // used is true if this slot is valid. If false, it's free for reuse. + used bool + theirKeyId uint32 + myKeyId uint32 + sendAESKey, recvAESKey []byte + sendMACKey, recvMACKey []byte + theirLastCtr [8]byte +} + +// akeKeys are generated during key exchange. There's one set for the reveal +// signature message and another for the signature message. In the protocol +// spec the latter are indicated with a prime mark. +type akeKeys struct { + c [16]byte + m1, m2 [32]byte +} + +func (c *Conversation) rand() io.Reader { + if c.Rand != nil { + return c.Rand + } + return rand.Reader +} + +func (c *Conversation) randMPI(buf []byte) *big.Int { + _, err := io.ReadFull(c.rand(), buf) + if err != nil { + panic("otr: short read from random source") + } + + return new(big.Int).SetBytes(buf) +} + +// tlv represents the type-length value from the protocol. +type tlv struct { + typ, length uint16 + data []byte +} + +const ( + tlvTypePadding = 0 + tlvTypeDisconnected = 1 + tlvTypeSMP1 = 2 + tlvTypeSMP2 = 3 + tlvTypeSMP3 = 4 + tlvTypeSMP4 = 5 + tlvTypeSMPAbort = 6 + tlvTypeSMP1WithQuestion = 7 +) + +// Receive handles a message from a peer. It returns a human readable message, +// an indicator of whether that message was encrypted, a hint about the +// encryption state and zero or more messages to send back to the peer. +// These messages do not need to be passed to Send before transmission. +func (c *Conversation) Receive(in []byte) (out []byte, encrypted bool, change SecurityChange, toSend [][]byte, err error) { + if bytes.HasPrefix(in, fragmentPrefix) { + in, err = c.processFragment(in) + if in == nil || err != nil { + return + } + } + + if bytes.HasPrefix(in, msgPrefix) && in[len(in)-1] == '.' { + in = in[len(msgPrefix) : len(in)-1] + } else if version := isQuery(in); version > 0 { + c.authState = authStateAwaitingDHKey + c.reset() + toSend = c.encode(c.generateDHCommit()) + return + } else { + // plaintext message + out = in + return + } + + msg := make([]byte, base64.StdEncoding.DecodedLen(len(in))) + msgLen, err := base64.StdEncoding.Decode(msg, in) + if err != nil { + err = errors.New("otr: invalid base64 encoding in message") + return + } + msg = msg[:msgLen] + + // The first two bytes are the protocol version (2) + if len(msg) < 3 || msg[0] != 0 || msg[1] != 2 { + err = errors.New("otr: invalid OTR message") + return + } + + msgType := int(msg[2]) + msg = msg[3:] + + switch msgType { + case msgTypeDHCommit: + switch c.authState { + case authStateNone: + c.authState = authStateAwaitingRevealSig + if err = c.processDHCommit(msg); err != nil { + return + } + c.reset() + toSend = c.encode(c.generateDHKey()) + return + case authStateAwaitingDHKey: + // This is a 'SYN-crossing'. The greater digest wins. + var cmp int + if cmp, err = c.compareToDHCommit(msg); err != nil { + return + } + if cmp > 0 { + // We win. Retransmit DH commit. + toSend = c.encode(c.serializeDHCommit()) + return + } else { + // They win. We forget about our DH commit. + c.authState = authStateAwaitingRevealSig + if err = c.processDHCommit(msg); err != nil { + return + } + c.reset() + toSend = c.encode(c.generateDHKey()) + return + } + case authStateAwaitingRevealSig: + if err = c.processDHCommit(msg); err != nil { + return + } + toSend = c.encode(c.serializeDHKey()) + case authStateAwaitingSig: + if err = c.processDHCommit(msg); err != nil { + return + } + c.reset() + toSend = c.encode(c.generateDHKey()) + c.authState = authStateAwaitingRevealSig + default: + panic("bad state") + } + case msgTypeDHKey: + switch c.authState { + case authStateAwaitingDHKey: + var isSame bool + if isSame, err = c.processDHKey(msg); err != nil { + return + } + if isSame { + err = errors.New("otr: unexpected duplicate DH key") + return + } + toSend = c.encode(c.generateRevealSig()) + c.authState = authStateAwaitingSig + case authStateAwaitingSig: + var isSame bool + if isSame, err = c.processDHKey(msg); err != nil { + return + } + if isSame { + toSend = c.encode(c.serializeDHKey()) + } + } + case msgTypeRevealSig: + if c.authState != authStateAwaitingRevealSig { + return + } + if err = c.processRevealSig(msg); err != nil { + return + } + toSend = c.encode(c.generateSig()) + c.authState = authStateNone + c.state = stateEncrypted + change = NewKeys + case msgTypeSig: + if c.authState != authStateAwaitingSig { + return + } + if err = c.processSig(msg); err != nil { + return + } + c.authState = authStateNone + c.state = stateEncrypted + change = NewKeys + case msgTypeData: + if c.state != stateEncrypted { + err = errors.New("otr: encrypted message received without encrypted session established") + return + } + var tlvs []tlv + out, tlvs, err = c.processData(msg) + encrypted = true + + EachTLV: + for _, inTLV := range tlvs { + switch inTLV.typ { + case tlvTypeDisconnected: + change = ConversationEnded + c.state = stateFinished + break EachTLV + case tlvTypeSMP1, tlvTypeSMP2, tlvTypeSMP3, tlvTypeSMP4, tlvTypeSMPAbort, tlvTypeSMP1WithQuestion: + var reply tlv + var complete bool + reply, complete, err = c.processSMP(inTLV) + if err == smpSecretMissingError { + err = nil + change = SMPSecretNeeded + c.smp.saved = &inTLV + return + } + if err == smpFailureError { + err = nil + change = SMPFailed + } else if complete { + change = SMPComplete + } + if reply.typ != 0 { + toSend = c.encode(c.generateData(nil, &reply)) + } + break EachTLV + default: + // skip unknown TLVs + } + } + default: + err = errors.New("otr: unknown message type " + strconv.Itoa(msgType)) + } + + return +} + +// Send takes a human readable message from the local user, possibly encrypts +// it and returns zero one or more messages to send to the peer. +func (c *Conversation) Send(msg []byte) ([][]byte, error) { + switch c.state { + case statePlaintext: + return [][]byte{msg}, nil + case stateEncrypted: + return c.encode(c.generateData(msg, nil)), nil + case stateFinished: + return nil, errors.New("otr: cannot send message because secure conversation has finished") + } + + return nil, errors.New("otr: cannot send message in current state") +} + +// SMPQuestion returns the human readable challenge question from the peer. +// It's only valid after Receive has returned SMPSecretNeeded. +func (c *Conversation) SMPQuestion() string { + return c.smp.question +} + +// Authenticate begins an authentication with the peer. Authentication involves +// an optional challenge message and a shared secret. The authentication +// proceeds until either Receive returns SMPComplete, SMPSecretNeeded (which +// indicates that a new authentication is happening and thus this one was +// aborted) or SMPFailed. +func (c *Conversation) Authenticate(question string, mutualSecret []byte) (toSend [][]byte, err error) { + if c.state != stateEncrypted { + err = errors.New("otr: can't authenticate a peer without a secure conversation established") + return + } + + if c.smp.saved != nil { + c.calcSMPSecret(mutualSecret, false /* they started it */) + + var out tlv + var complete bool + out, complete, err = c.processSMP(*c.smp.saved) + if complete { + panic("SMP completed on the first message") + } + c.smp.saved = nil + if out.typ != 0 { + toSend = c.encode(c.generateData(nil, &out)) + } + return + } + + c.calcSMPSecret(mutualSecret, true /* we started it */) + outs := c.startSMP(question) + for _, out := range outs { + toSend = append(toSend, c.encode(c.generateData(nil, &out))...) + } + return +} + +// End ends a secure conversation by generating a termination message for +// the peer and switches to unencrypted communication. +func (c *Conversation) End() (toSend [][]byte) { + switch c.state { + case statePlaintext: + return nil + case stateEncrypted: + c.state = statePlaintext + return c.encode(c.generateData(nil, &tlv{typ: tlvTypeDisconnected})) + case stateFinished: + c.state = statePlaintext + return nil + } + panic("unreachable") +} + +// IsEncrypted returns true if a message passed to Send would be encrypted +// before transmission. This result remains valid until the next call to +// Receive or End, which may change the state of the Conversation. +func (c *Conversation) IsEncrypted() bool { + return c.state == stateEncrypted +} + +var fragmentError = errors.New("otr: invalid OTR fragment") + +// processFragment processes a fragmented OTR message and possibly returns a +// complete message. Fragmented messages look like "?OTR,k,n,msg," where k is +// the fragment number (starting from 1), n is the number of fragments in this +// message and msg is a substring of the base64 encoded message. +func (c *Conversation) processFragment(in []byte) (out []byte, err error) { + in = in[len(fragmentPrefix):] // remove "?OTR," + parts := bytes.Split(in, fragmentPartSeparator) + if len(parts) != 4 || len(parts[3]) != 0 { + return nil, fragmentError + } + + k, err := strconv.Atoi(string(parts[0])) + if err != nil { + return nil, fragmentError + } + + n, err := strconv.Atoi(string(parts[1])) + if err != nil { + return nil, fragmentError + } + + if k < 1 || n < 1 || k > n { + return nil, fragmentError + } + + if k == 1 { + c.frag = append(c.frag[:0], parts[2]...) + c.k, c.n = k, n + } else if n == c.n && k == c.k+1 { + c.frag = append(c.frag, parts[2]...) + c.k++ + } else { + c.frag = c.frag[:0] + c.n, c.k = 0, 0 + } + + if c.n > 0 && c.k == c.n { + c.n, c.k = 0, 0 + return c.frag, nil + } + + return nil, nil +} + +func (c *Conversation) generateDHCommit() []byte { + _, err := io.ReadFull(c.rand(), c.r[:]) + if err != nil { + panic("otr: short read from random source") + } + + var xBytes [dhPrivateBytes]byte + c.x = c.randMPI(xBytes[:]) + c.gx = new(big.Int).Exp(g, c.x, p) + c.gy = nil + c.gxBytes = appendMPI(nil, c.gx) + + h := sha256.New() + h.Write(c.gxBytes) + h.Sum(c.digest[:0]) + + aesCipher, err := aes.NewCipher(c.r[:]) + if err != nil { + panic(err.Error()) + } + + var iv [aes.BlockSize]byte + ctr := cipher.NewCTR(aesCipher, iv[:]) + ctr.XORKeyStream(c.gxBytes, c.gxBytes) + + return c.serializeDHCommit() +} + +func (c *Conversation) serializeDHCommit() []byte { + var ret []byte + ret = appendU16(ret, 2) // protocol version + ret = append(ret, msgTypeDHCommit) + ret = appendData(ret, c.gxBytes) + ret = appendData(ret, c.digest[:]) + return ret +} + +func (c *Conversation) processDHCommit(in []byte) error { + var ok1, ok2 bool + c.gxBytes, in, ok1 = getData(in) + digest, in, ok2 := getData(in) + if !ok1 || !ok2 || len(in) > 0 { + return errors.New("otr: corrupt DH commit message") + } + copy(c.digest[:], digest) + return nil +} + +func (c *Conversation) compareToDHCommit(in []byte) (int, error) { + _, in, ok1 := getData(in) + digest, in, ok2 := getData(in) + if !ok1 || !ok2 || len(in) > 0 { + return 0, errors.New("otr: corrupt DH commit message") + } + return bytes.Compare(c.digest[:], digest), nil +} + +func (c *Conversation) generateDHKey() []byte { + var yBytes [dhPrivateBytes]byte + c.y = c.randMPI(yBytes[:]) + c.gy = new(big.Int).Exp(g, c.y, p) + return c.serializeDHKey() +} + +func (c *Conversation) serializeDHKey() []byte { + var ret []byte + ret = appendU16(ret, 2) // protocol version + ret = append(ret, msgTypeDHKey) + ret = appendMPI(ret, c.gy) + return ret +} + +func (c *Conversation) processDHKey(in []byte) (isSame bool, err error) { + gy, in, ok := getMPI(in) + if !ok { + err = errors.New("otr: corrupt DH key message") + return + } + if gy.Cmp(g) < 0 || gy.Cmp(pMinus2) > 0 { + err = errors.New("otr: DH value out of range") + return + } + if c.gy != nil { + isSame = c.gy.Cmp(gy) == 0 + return + } + c.gy = gy + return +} + +func (c *Conversation) generateEncryptedSignature(keys *akeKeys, xFirst bool) ([]byte, []byte) { + var xb []byte + xb = c.PrivateKey.PublicKey.Serialize(xb) + + var verifyData []byte + if xFirst { + verifyData = appendMPI(verifyData, c.gx) + verifyData = appendMPI(verifyData, c.gy) + } else { + verifyData = appendMPI(verifyData, c.gy) + verifyData = appendMPI(verifyData, c.gx) + } + verifyData = append(verifyData, xb...) + verifyData = appendU32(verifyData, c.myKeyId) + + mac := hmac.New(sha256.New, keys.m1[:]) + mac.Write(verifyData) + mb := mac.Sum(nil) + + xb = appendU32(xb, c.myKeyId) + xb = append(xb, c.PrivateKey.Sign(c.rand(), mb)...) + + aesCipher, err := aes.NewCipher(keys.c[:]) + if err != nil { + panic(err.Error()) + } + var iv [aes.BlockSize]byte + ctr := cipher.NewCTR(aesCipher, iv[:]) + ctr.XORKeyStream(xb, xb) + + mac = hmac.New(sha256.New, keys.m2[:]) + encryptedSig := appendData(nil, xb) + mac.Write(encryptedSig) + + return encryptedSig, mac.Sum(nil) +} + +func (c *Conversation) generateRevealSig() []byte { + s := new(big.Int).Exp(c.gy, c.x, p) + c.calcAKEKeys(s) + c.myKeyId++ + + encryptedSig, mac := c.generateEncryptedSignature(&c.revealKeys, true /* gx comes first */) + + c.myCurrentDHPub = c.gx + c.myCurrentDHPriv = c.x + c.rotateDHKeys() + incCounter(&c.myCounter) + + var ret []byte + ret = appendU16(ret, 2) + ret = append(ret, msgTypeRevealSig) + ret = appendData(ret, c.r[:]) + ret = append(ret, encryptedSig...) + ret = append(ret, mac[:20]...) + return ret +} + +func (c *Conversation) processEncryptedSig(encryptedSig, theirMAC []byte, keys *akeKeys, xFirst bool) error { + mac := hmac.New(sha256.New, keys.m2[:]) + mac.Write(appendData(nil, encryptedSig)) + myMAC := mac.Sum(nil)[:20] + + if len(myMAC) != len(theirMAC) || subtle.ConstantTimeCompare(myMAC, theirMAC) == 0 { + return errors.New("bad signature MAC in encrypted signature") + } + + aesCipher, err := aes.NewCipher(keys.c[:]) + if err != nil { + panic(err.Error()) + } + var iv [aes.BlockSize]byte + ctr := cipher.NewCTR(aesCipher, iv[:]) + ctr.XORKeyStream(encryptedSig, encryptedSig) + + sig := encryptedSig + sig, ok1 := c.TheirPublicKey.Parse(sig) + keyId, sig, ok2 := getU32(sig) + if !ok1 || !ok2 { + return errors.New("otr: corrupt encrypted signature") + } + + var verifyData []byte + if xFirst { + verifyData = appendMPI(verifyData, c.gx) + verifyData = appendMPI(verifyData, c.gy) + } else { + verifyData = appendMPI(verifyData, c.gy) + verifyData = appendMPI(verifyData, c.gx) + } + verifyData = c.TheirPublicKey.Serialize(verifyData) + verifyData = appendU32(verifyData, keyId) + + mac = hmac.New(sha256.New, keys.m1[:]) + mac.Write(verifyData) + mb := mac.Sum(nil) + + sig, ok1 = c.TheirPublicKey.Verify(mb, sig) + if !ok1 { + return errors.New("bad signature in encrypted signature") + } + if len(sig) > 0 { + return errors.New("corrupt encrypted signature") + } + + c.theirKeyId = keyId + zero(c.theirLastCtr[:]) + return nil +} + +func (c *Conversation) processRevealSig(in []byte) error { + r, in, ok1 := getData(in) + encryptedSig, in, ok2 := getData(in) + theirMAC := in + if !ok1 || !ok2 || len(theirMAC) != 20 { + return errors.New("otr: corrupt reveal signature message") + } + + aesCipher, err := aes.NewCipher(r) + if err != nil { + return errors.New("otr: cannot create AES cipher from reveal signature message: " + err.Error()) + } + var iv [aes.BlockSize]byte + ctr := cipher.NewCTR(aesCipher, iv[:]) + ctr.XORKeyStream(c.gxBytes, c.gxBytes) + h := sha256.New() + h.Write(c.gxBytes) + digest := h.Sum(nil) + if len(digest) != len(c.digest) || subtle.ConstantTimeCompare(digest, c.digest[:]) == 0 { + return errors.New("otr: bad commit MAC in reveal signature message") + } + var rest []byte + c.gx, rest, ok1 = getMPI(c.gxBytes) + if !ok1 || len(rest) > 0 { + return errors.New("otr: gx corrupt after decryption") + } + if c.gx.Cmp(g) < 0 || c.gx.Cmp(pMinus2) > 0 { + return errors.New("otr: DH value out of range") + } + s := new(big.Int).Exp(c.gx, c.y, p) + c.calcAKEKeys(s) + + if err := c.processEncryptedSig(encryptedSig, theirMAC, &c.revealKeys, true /* gx comes first */); err != nil { + return errors.New("otr: in reveal signature message: " + err.Error()) + } + + c.theirCurrentDHPub = c.gx + c.theirLastDHPub = nil + + return nil +} + +func (c *Conversation) generateSig() []byte { + c.myKeyId++ + + encryptedSig, mac := c.generateEncryptedSignature(&c.sigKeys, false /* gy comes first */) + + c.myCurrentDHPub = c.gy + c.myCurrentDHPriv = c.y + c.rotateDHKeys() + incCounter(&c.myCounter) + + var ret []byte + ret = appendU16(ret, 2) + ret = append(ret, msgTypeSig) + ret = append(ret, encryptedSig...) + ret = append(ret, mac[:macPrefixBytes]...) + return ret +} + +func (c *Conversation) processSig(in []byte) error { + encryptedSig, in, ok1 := getData(in) + theirMAC := in + if !ok1 || len(theirMAC) != macPrefixBytes { + return errors.New("otr: corrupt signature message") + } + + if err := c.processEncryptedSig(encryptedSig, theirMAC, &c.sigKeys, false /* gy comes first */); err != nil { + return errors.New("otr: in signature message: " + err.Error()) + } + + c.theirCurrentDHPub = c.gy + c.theirLastDHPub = nil + + return nil +} + +func (c *Conversation) rotateDHKeys() { + // evict slots using our retired key id + for i := range c.keySlots { + slot := &c.keySlots[i] + if slot.used && slot.myKeyId == c.myKeyId-1 { + slot.used = false + c.oldMACs = append(c.oldMACs, slot.recvMACKey...) + } + } + + c.myLastDHPriv = c.myCurrentDHPriv + c.myLastDHPub = c.myCurrentDHPub + + var xBytes [dhPrivateBytes]byte + c.myCurrentDHPriv = c.randMPI(xBytes[:]) + c.myCurrentDHPub = new(big.Int).Exp(g, c.myCurrentDHPriv, p) + c.myKeyId++ +} + +func (c *Conversation) processData(in []byte) (out []byte, tlvs []tlv, err error) { + origIn := in + flags, in, ok1 := getU8(in) + theirKeyId, in, ok2 := getU32(in) + myKeyId, in, ok3 := getU32(in) + y, in, ok4 := getMPI(in) + counter, in, ok5 := getNBytes(in, 8) + encrypted, in, ok6 := getData(in) + macedData := origIn[:len(origIn)-len(in)] + theirMAC, in, ok7 := getNBytes(in, macPrefixBytes) + _, in, ok8 := getData(in) + if !ok1 || !ok2 || !ok3 || !ok4 || !ok5 || !ok6 || !ok7 || !ok8 || len(in) > 0 { + err = errors.New("otr: corrupt data message") + return + } + + ignoreErrors := flags&1 != 0 + + slot, err := c.calcDataKeys(myKeyId, theirKeyId) + if err != nil { + if ignoreErrors { + err = nil + } + return + } + + mac := hmac.New(sha1.New, slot.recvMACKey) + mac.Write([]byte{0, 2, 3}) + mac.Write(macedData) + myMAC := mac.Sum(nil) + if len(myMAC) != len(theirMAC) || subtle.ConstantTimeCompare(myMAC, theirMAC) == 0 { + if !ignoreErrors { + err = errors.New("otr: bad MAC on data message") + } + return + } + + if bytes.Compare(counter, slot.theirLastCtr[:]) <= 0 { + err = errors.New("otr: counter regressed") + return + } + copy(slot.theirLastCtr[:], counter) + + var iv [aes.BlockSize]byte + copy(iv[:], counter) + aesCipher, err := aes.NewCipher(slot.recvAESKey) + if err != nil { + panic(err.Error()) + } + ctr := cipher.NewCTR(aesCipher, iv[:]) + ctr.XORKeyStream(encrypted, encrypted) + decrypted := encrypted + + if myKeyId == c.myKeyId { + c.rotateDHKeys() + } + if theirKeyId == c.theirKeyId { + // evict slots using their retired key id + for i := range c.keySlots { + slot := &c.keySlots[i] + if slot.used && slot.theirKeyId == theirKeyId-1 { + slot.used = false + c.oldMACs = append(c.oldMACs, slot.recvMACKey...) + } + } + + c.theirLastDHPub = c.theirCurrentDHPub + c.theirKeyId++ + c.theirCurrentDHPub = y + } + + if nulPos := bytes.IndexByte(decrypted, 0); nulPos >= 0 { + out = decrypted[:nulPos] + tlvData := decrypted[nulPos+1:] + for len(tlvData) > 0 { + var t tlv + var ok1, ok2, ok3 bool + + t.typ, tlvData, ok1 = getU16(tlvData) + t.length, tlvData, ok2 = getU16(tlvData) + t.data, tlvData, ok3 = getNBytes(tlvData, int(t.length)) + if !ok1 || !ok2 || !ok3 { + err = errors.New("otr: corrupt tlv data") + return + } + tlvs = append(tlvs, t) + } + } else { + out = decrypted + } + + return +} + +func (c *Conversation) generateData(msg []byte, extra *tlv) []byte { + slot, err := c.calcDataKeys(c.myKeyId-1, c.theirKeyId) + if err != nil { + panic("otr: failed to generate sending keys: " + err.Error()) + } + + var plaintext []byte + plaintext = append(plaintext, msg...) + plaintext = append(plaintext, 0) + + padding := paddingGranularity - ((len(plaintext) + 4) % paddingGranularity) + plaintext = appendU16(plaintext, tlvTypePadding) + plaintext = appendU16(plaintext, uint16(padding)) + for i := 0; i < padding; i++ { + plaintext = append(plaintext, 0) + } + + if extra != nil { + plaintext = appendU16(plaintext, extra.typ) + plaintext = appendU16(plaintext, uint16(len(extra.data))) + plaintext = append(plaintext, extra.data...) + } + + encrypted := make([]byte, len(plaintext)) + + var iv [aes.BlockSize]byte + copy(iv[:], c.myCounter[:]) + aesCipher, err := aes.NewCipher(slot.sendAESKey) + if err != nil { + panic(err.Error()) + } + ctr := cipher.NewCTR(aesCipher, iv[:]) + ctr.XORKeyStream(encrypted, plaintext) + + var ret []byte + ret = appendU16(ret, 2) + ret = append(ret, msgTypeData) + ret = append(ret, 0 /* flags */) + ret = appendU32(ret, c.myKeyId-1) + ret = appendU32(ret, c.theirKeyId) + ret = appendMPI(ret, c.myCurrentDHPub) + ret = append(ret, c.myCounter[:]...) + ret = appendData(ret, encrypted) + + mac := hmac.New(sha1.New, slot.sendMACKey) + mac.Write(ret) + ret = append(ret, mac.Sum(nil)[:macPrefixBytes]...) + ret = appendData(ret, c.oldMACs) + c.oldMACs = nil + incCounter(&c.myCounter) + + return ret +} + +func incCounter(counter *[8]byte) { + for i := 7; i >= 0; i-- { + counter[i]++ + if counter[i] > 0 { + break + } + } +} + +// calcDataKeys computes the keys used to encrypt a data message given the key +// IDs. +func (c *Conversation) calcDataKeys(myKeyId, theirKeyId uint32) (slot *keySlot, err error) { + // Check for a cache hit. + for i := range c.keySlots { + slot = &c.keySlots[i] + if slot.used && slot.theirKeyId == theirKeyId && slot.myKeyId == myKeyId { + return + } + } + + // Find an empty slot to write into. + slot = nil + for i := range c.keySlots { + if !c.keySlots[i].used { + slot = &c.keySlots[i] + break + } + } + if slot == nil { + return nil, errors.New("otr: internal error: no more key slots") + } + + var myPriv, myPub, theirPub *big.Int + + if myKeyId == c.myKeyId { + myPriv = c.myCurrentDHPriv + myPub = c.myCurrentDHPub + } else if myKeyId == c.myKeyId-1 { + myPriv = c.myLastDHPriv + myPub = c.myLastDHPub + } else { + err = errors.New("otr: peer requested keyid " + strconv.FormatUint(uint64(myKeyId), 10) + " when I'm on " + strconv.FormatUint(uint64(c.myKeyId), 10)) + return + } + + if theirKeyId == c.theirKeyId { + theirPub = c.theirCurrentDHPub + } else if theirKeyId == c.theirKeyId-1 && c.theirLastDHPub != nil { + theirPub = c.theirLastDHPub + } else { + err = errors.New("otr: peer requested keyid " + strconv.FormatUint(uint64(myKeyId), 10) + " when they're on " + strconv.FormatUint(uint64(c.myKeyId), 10)) + return + } + + var sendPrefixByte, recvPrefixByte [1]byte + + if myPub.Cmp(theirPub) > 0 { + // we're the high end + sendPrefixByte[0], recvPrefixByte[0] = 1, 2 + } else { + // we're the low end + sendPrefixByte[0], recvPrefixByte[0] = 2, 1 + } + + s := new(big.Int).Exp(theirPub, myPriv, p) + sBytes := appendMPI(nil, s) + + h := sha1.New() + h.Write(sendPrefixByte[:]) + h.Write(sBytes) + slot.sendAESKey = h.Sum(slot.sendAESKey[:0])[:16] + + h.Reset() + h.Write(slot.sendAESKey) + slot.sendMACKey = h.Sum(slot.sendMACKey[:0]) + + h.Reset() + h.Write(recvPrefixByte[:]) + h.Write(sBytes) + slot.recvAESKey = h.Sum(slot.recvAESKey[:0])[:16] + + h.Reset() + h.Write(slot.recvAESKey) + slot.recvMACKey = h.Sum(slot.recvMACKey[:0]) + + slot.theirKeyId = theirKeyId + slot.myKeyId = myKeyId + slot.used = true + + zero(slot.theirLastCtr[:]) + return +} + +func (c *Conversation) calcAKEKeys(s *big.Int) { + mpi := appendMPI(nil, s) + h := sha256.New() + + var cBytes [32]byte + hashWithPrefix(c.SSID[:], 0, mpi, h) + + hashWithPrefix(cBytes[:], 1, mpi, h) + copy(c.revealKeys.c[:], cBytes[:16]) + copy(c.sigKeys.c[:], cBytes[16:]) + + hashWithPrefix(c.revealKeys.m1[:], 2, mpi, h) + hashWithPrefix(c.revealKeys.m2[:], 3, mpi, h) + hashWithPrefix(c.sigKeys.m1[:], 4, mpi, h) + hashWithPrefix(c.sigKeys.m2[:], 5, mpi, h) +} + +func hashWithPrefix(out []byte, prefix byte, in []byte, h hash.Hash) { + h.Reset() + var p [1]byte + p[0] = prefix + h.Write(p[:]) + h.Write(in) + if len(out) == h.Size() { + h.Sum(out[:0]) + } else { + digest := h.Sum(nil) + copy(out, digest) + } +} + +func (c *Conversation) encode(msg []byte) [][]byte { + b64 := make([]byte, base64.StdEncoding.EncodedLen(len(msg))+len(msgPrefix)+1) + base64.StdEncoding.Encode(b64[len(msgPrefix):], msg) + copy(b64, msgPrefix) + b64[len(b64)-1] = '.' + + if c.FragmentSize < minFragmentSize || len(b64) <= c.FragmentSize { + // We can encode this in a single fragment. + return [][]byte{b64} + } + + // We have to fragment this message. + var ret [][]byte + bytesPerFragment := c.FragmentSize - minFragmentSize + numFragments := (len(b64) + bytesPerFragment) / bytesPerFragment + + for i := 0; i < numFragments; i++ { + frag := []byte("?OTR," + strconv.Itoa(i+1) + "," + strconv.Itoa(numFragments) + ",") + todo := bytesPerFragment + if todo > len(b64) { + todo = len(b64) + } + frag = append(frag, b64[:todo]...) + b64 = b64[todo:] + frag = append(frag, ',') + ret = append(ret, frag) + } + + return ret +} + +func (c *Conversation) reset() { + c.myKeyId = 0 + + for i := range c.keySlots { + c.keySlots[i].used = false + } +} + +type PublicKey struct { + dsa.PublicKey +} + +func (pk *PublicKey) Parse(in []byte) ([]byte, bool) { + var ok bool + var pubKeyType uint16 + + if pubKeyType, in, ok = getU16(in); !ok || pubKeyType != 0 { + return nil, false + } + if pk.P, in, ok = getMPI(in); !ok { + return nil, false + } + if pk.Q, in, ok = getMPI(in); !ok { + return nil, false + } + if pk.G, in, ok = getMPI(in); !ok { + return nil, false + } + if pk.Y, in, ok = getMPI(in); !ok { + return nil, false + } + + return in, true +} + +func (pk *PublicKey) Serialize(in []byte) []byte { + in = appendU16(in, 0) + in = appendMPI(in, pk.P) + in = appendMPI(in, pk.Q) + in = appendMPI(in, pk.G) + in = appendMPI(in, pk.Y) + return in +} + +// Fingerprint returns the 20-byte, binary fingerprint of the PublicKey. +func (pk *PublicKey) Fingerprint() []byte { + b := pk.Serialize(nil) + h := sha1.New() + h.Write(b[2:]) + return h.Sum(nil) +} + +func (pk *PublicKey) Verify(hashed, sig []byte) ([]byte, bool) { + if len(sig) != 2*dsaSubgroupBytes { + return nil, false + } + r := new(big.Int).SetBytes(sig[:dsaSubgroupBytes]) + s := new(big.Int).SetBytes(sig[dsaSubgroupBytes:]) + ok := dsa.Verify(&pk.PublicKey, hashed, r, s) + return sig[dsaSubgroupBytes*2:], ok +} + +type PrivateKey struct { + PublicKey + dsa.PrivateKey +} + +func (priv *PrivateKey) Sign(rand io.Reader, hashed []byte) []byte { + r, s, err := dsa.Sign(rand, &priv.PrivateKey, hashed) + if err != nil { + panic(err.Error()) + } + rBytes := r.Bytes() + sBytes := s.Bytes() + if len(rBytes) > dsaSubgroupBytes || len(sBytes) > dsaSubgroupBytes { + panic("DSA signature too large") + } + + out := make([]byte, 2*dsaSubgroupBytes) + copy(out[dsaSubgroupBytes-len(rBytes):], rBytes) + copy(out[len(out)-len(sBytes):], sBytes) + return out +} + +func (priv *PrivateKey) Serialize(in []byte) []byte { + in = priv.PublicKey.Serialize(in) + in = appendMPI(in, priv.PrivateKey.X) + return in +} + +func (priv *PrivateKey) Parse(in []byte) ([]byte, bool) { + in, ok := priv.PublicKey.Parse(in) + if !ok { + return in, ok + } + priv.PrivateKey.PublicKey = priv.PublicKey.PublicKey + priv.PrivateKey.X, in, ok = getMPI(in) + return in, ok +} + +func (priv *PrivateKey) Generate(rand io.Reader) { + if err := dsa.GenerateParameters(&priv.PrivateKey.PublicKey.Parameters, rand, dsa.L1024N160); err != nil { + panic(err.Error()) + } + if err := dsa.GenerateKey(&priv.PrivateKey, rand); err != nil { + panic(err.Error()) + } + priv.PublicKey.PublicKey = priv.PrivateKey.PublicKey +} + +func notHex(r rune) bool { + if r >= '0' && r <= '9' || + r >= 'a' && r <= 'f' || + r >= 'A' && r <= 'F' { + return false + } + + return true +} + +// Import parses the contents of a libotr private key file. +func (priv *PrivateKey) Import(in []byte) bool { + mpiStart := []byte(" #") + + mpis := make([]*big.Int, 5) + + for i := 0; i < len(mpis); i++ { + start := bytes.Index(in, mpiStart) + if start == -1 { + return false + } + in = in[start+len(mpiStart):] + end := bytes.IndexFunc(in, notHex) + if end == -1 { + return false + } + hexBytes := in[:end] + in = in[end:] + + if len(hexBytes)&1 != 0 { + return false + } + + mpiBytes := make([]byte, len(hexBytes)/2) + if _, err := hex.Decode(mpiBytes, hexBytes); err != nil { + return false + } + + mpis[i] = new(big.Int).SetBytes(mpiBytes) + } + + for _, mpi := range mpis { + if mpi.Sign() <= 0 { + return false + } + } + + priv.PrivateKey.P = mpis[0] + priv.PrivateKey.Q = mpis[1] + priv.PrivateKey.G = mpis[2] + priv.PrivateKey.Y = mpis[3] + priv.PrivateKey.X = mpis[4] + priv.PublicKey.PublicKey = priv.PrivateKey.PublicKey + + a := new(big.Int).Exp(priv.PrivateKey.G, priv.PrivateKey.X, priv.PrivateKey.P) + return a.Cmp(priv.PrivateKey.Y) == 0 +} + +func getU8(in []byte) (uint8, []byte, bool) { + if len(in) < 1 { + return 0, in, false + } + return in[0], in[1:], true +} + +func getU16(in []byte) (uint16, []byte, bool) { + if len(in) < 2 { + return 0, in, false + } + r := uint16(in[0])<<8 | uint16(in[1]) + return r, in[2:], true +} + +func getU32(in []byte) (uint32, []byte, bool) { + if len(in) < 4 { + return 0, in, false + } + r := uint32(in[0])<<24 | uint32(in[1])<<16 | uint32(in[2])<<8 | uint32(in[3]) + return r, in[4:], true +} + +func getMPI(in []byte) (*big.Int, []byte, bool) { + l, in, ok := getU32(in) + if !ok || uint32(len(in)) < l { + return nil, in, false + } + r := new(big.Int).SetBytes(in[:l]) + return r, in[l:], true +} + +func getData(in []byte) ([]byte, []byte, bool) { + l, in, ok := getU32(in) + if !ok || uint32(len(in)) < l { + return nil, in, false + } + return in[:l], in[l:], true +} + +func getNBytes(in []byte, n int) ([]byte, []byte, bool) { + if len(in) < n { + return nil, in, false + } + return in[:n], in[n:], true +} + +func appendU16(out []byte, v uint16) []byte { + out = append(out, byte(v>>8), byte(v)) + return out +} + +func appendU32(out []byte, v uint32) []byte { + out = append(out, byte(v>>24), byte(v>>16), byte(v>>8), byte(v)) + return out +} + +func appendData(out, v []byte) []byte { + out = appendU32(out, uint32(len(v))) + out = append(out, v...) + return out +} + +func appendMPI(out []byte, v *big.Int) []byte { + vBytes := v.Bytes() + out = appendU32(out, uint32(len(vBytes))) + out = append(out, vBytes...) + return out +} + +func appendMPIs(out []byte, mpis ...*big.Int) []byte { + for _, mpi := range mpis { + out = appendMPI(out, mpi) + } + return out +} + +func zero(b []byte) { + for i := range b { + b[i] = 0 + } +} diff --git a/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/otr_test.go b/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/otr_test.go new file mode 100644 index 000000000..cfcd062b2 --- /dev/null +++ b/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/otr_test.go @@ -0,0 +1,470 @@ +// Copyright 2012 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package otr + +import ( + "bufio" + "bytes" + "crypto/rand" + "encoding/hex" + "math/big" + "os" + "os/exec" + "testing" +) + +var isQueryTests = []struct { + msg string + expectedVersion int +}{ + {"foo", 0}, + {"?OtR", 0}, + {"?OtR?", 0}, + {"?OTR?", 0}, + {"?OTRv?", 0}, + {"?OTRv1?", 0}, + {"?OTR?v1?", 0}, + {"?OTR?v?", 0}, + {"?OTR?v2?", 2}, + {"?OTRv2?", 2}, + {"?OTRv23?", 2}, + {"?OTRv23 ?", 0}, +} + +func TestIsQuery(t *testing.T) { + for i, test := range isQueryTests { + version := isQuery([]byte(test.msg)) + if version != test.expectedVersion { + t.Errorf("#%d: got %d, want %d", i, version, test.expectedVersion) + } + } +} + +var alicePrivateKeyHex = "000000000080c81c2cb2eb729b7e6fd48e975a932c638b3a9055478583afa46755683e30102447f6da2d8bec9f386bbb5da6403b0040fee8650b6ab2d7f32c55ab017ae9b6aec8c324ab5844784e9a80e194830d548fb7f09a0410df2c4d5c8bc2b3e9ad484e65412be689cf0834694e0839fb2954021521ffdffb8f5c32c14dbf2020b3ce7500000014da4591d58def96de61aea7b04a8405fe1609308d000000808ddd5cb0b9d66956e3dea5a915d9aba9d8a6e7053b74dadb2fc52f9fe4e5bcc487d2305485ed95fed026ad93f06ebb8c9e8baf693b7887132c7ffdd3b0f72f4002ff4ed56583ca7c54458f8c068ca3e8a4dfa309d1dd5d34e2a4b68e6f4338835e5e0fb4317c9e4c7e4806dafda3ef459cd563775a586dd91b1319f72621bf3f00000080b8147e74d8c45e6318c37731b8b33b984a795b3653c2cd1d65cc99efe097cb7eb2fa49569bab5aab6e8a1c261a27d0f7840a5e80b317e6683042b59b6dceca2879c6ffc877a465be690c15e4a42f9a7588e79b10faac11b1ce3741fcef7aba8ce05327a2c16d279ee1b3d77eb783fb10e3356caa25635331e26dd42b8396c4d00000001420bec691fea37ecea58a5c717142f0b804452f57" + +var aliceFingerprintHex = "0bb01c360424522e94ee9c346ce877a1a4288b2f" + +var bobPrivateKeyHex = "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" + +func TestKeySerialization(t *testing.T) { + var priv PrivateKey + alicePrivateKey, _ := hex.DecodeString(alicePrivateKeyHex) + rest, ok := priv.Parse(alicePrivateKey) + if !ok { + t.Error("failed to parse private key") + } + if len(rest) > 0 { + t.Error("data remaining after parsing private key") + } + + out := priv.Serialize(nil) + if !bytes.Equal(alicePrivateKey, out) { + t.Errorf("serialization (%x) is not equal to original (%x)", out, alicePrivateKey) + } + + aliceFingerprint, _ := hex.DecodeString(aliceFingerprintHex) + fingerprint := priv.PublicKey.Fingerprint() + if !bytes.Equal(aliceFingerprint, fingerprint) { + t.Errorf("fingerprint (%x) is not equal to expected value (%x)", fingerprint, aliceFingerprint) + } +} + +const libOTRPrivateKey = `(privkeys + (account +(name "foo@example.com") +(protocol prpl-jabber) +(private-key + (dsa + (p #00FC07ABCF0DC916AFF6E9AE47BEF60C7AB9B4D6B2469E436630E36F8A489BE812486A09F30B71224508654940A835301ACC525A4FF133FC152CC53DCC59D65C30A54F1993FE13FE63E5823D4C746DB21B90F9B9C00B49EC7404AB1D929BA7FBA12F2E45C6E0A651689750E8528AB8C031D3561FECEE72EBB4A090D450A9B7A857#) + (q #00997BD266EF7B1F60A5C23F3A741F2AEFD07A2081#) + (g #535E360E8A95EBA46A4F7DE50AD6E9B2A6DB785A66B64EB9F20338D2A3E8FB0E94725848F1AA6CC567CB83A1CC517EC806F2E92EAE71457E80B2210A189B91250779434B41FC8A8873F6DB94BEA7D177F5D59E7E114EE10A49CFD9CEF88AE43387023B672927BA74B04EB6BBB5E57597766A2F9CE3857D7ACE3E1E3BC1FC6F26#) + (y #0AC8670AD767D7A8D9D14CC1AC6744CD7D76F993B77FFD9E39DF01E5A6536EF65E775FCEF2A983E2A19BD6415500F6979715D9FD1257E1FE2B6F5E1E74B333079E7C880D39868462A93454B41877BE62E5EF0A041C2EE9C9E76BD1E12AE25D9628DECB097025DD625EF49C3258A1A3C0FF501E3DC673B76D7BABF349009B6ECF#) + (x #14D0345A3562C480A039E3C72764F72D79043216#) + ) + ) + ) +)` + +func TestParseLibOTRPrivateKey(t *testing.T) { + var priv PrivateKey + + if !priv.Import([]byte(libOTRPrivateKey)) { + t.Fatalf("Failed to import sample private key") + } +} + +func TestSignVerify(t *testing.T) { + var priv PrivateKey + alicePrivateKey, _ := hex.DecodeString(alicePrivateKeyHex) + _, ok := priv.Parse(alicePrivateKey) + if !ok { + t.Error("failed to parse private key") + } + + var msg [32]byte + rand.Reader.Read(msg[:]) + + sig := priv.Sign(rand.Reader, msg[:]) + rest, ok := priv.PublicKey.Verify(msg[:], sig) + if !ok { + t.Errorf("signature (%x) of %x failed to verify", sig, msg[:]) + } else if len(rest) > 0 { + t.Error("signature data remains after verification") + } + + sig[10] ^= 80 + _, ok = priv.PublicKey.Verify(msg[:], sig) + if ok { + t.Errorf("corrupted signature (%x) of %x verified", sig, msg[:]) + } +} + +func setupConversation(t *testing.T) (alice, bob *Conversation) { + alicePrivateKey, _ := hex.DecodeString(alicePrivateKeyHex) + bobPrivateKey, _ := hex.DecodeString(bobPrivateKeyHex) + + alice, bob = new(Conversation), new(Conversation) + + alice.PrivateKey = new(PrivateKey) + bob.PrivateKey = new(PrivateKey) + alice.PrivateKey.Parse(alicePrivateKey) + bob.PrivateKey.Parse(bobPrivateKey) + alice.FragmentSize = 100 + bob.FragmentSize = 100 + + if alice.IsEncrypted() { + t.Error("Alice believes that the conversation is secure before we've started") + } + if bob.IsEncrypted() { + t.Error("Bob believes that the conversation is secure before we've started") + } + + performHandshake(t, alice, bob) + return alice, bob +} + +func performHandshake(t *testing.T, alice, bob *Conversation) { + var alicesMessage, bobsMessage [][]byte + var out []byte + var aliceChange, bobChange SecurityChange + var err error + alicesMessage = append(alicesMessage, []byte(QueryMessage)) + + for round := 0; len(alicesMessage) > 0 || len(bobsMessage) > 0; round++ { + bobsMessage = nil + for i, msg := range alicesMessage { + out, _, bobChange, bobsMessage, err = bob.Receive(msg) + if len(out) > 0 { + t.Errorf("Bob generated output during key exchange, round %d, message %d", round, i) + } + if err != nil { + t.Fatalf("Bob returned an error, round %d, message %d (%x): %s", round, i, msg, err) + } + if len(bobsMessage) > 0 && i != len(alicesMessage)-1 { + t.Errorf("Bob produced output while processing a fragment, round %d, message %d", round, i) + } + } + + alicesMessage = nil + for i, msg := range bobsMessage { + out, _, aliceChange, alicesMessage, err = alice.Receive(msg) + if len(out) > 0 { + t.Errorf("Alice generated output during key exchange, round %d, message %d", round, i) + } + if err != nil { + t.Fatalf("Alice returned an error, round %d, message %d (%x): %s", round, i, msg, err) + } + if len(alicesMessage) > 0 && i != len(bobsMessage)-1 { + t.Errorf("Alice produced output while processing a fragment, round %d, message %d", round, i) + } + } + } + + if aliceChange != NewKeys { + t.Errorf("Alice terminated without signaling new keys") + } + if bobChange != NewKeys { + t.Errorf("Bob terminated without signaling new keys") + } + + if !bytes.Equal(alice.SSID[:], bob.SSID[:]) { + t.Errorf("Session identifiers don't match. Alice has %x, Bob has %x", alice.SSID[:], bob.SSID[:]) + } + + if !alice.IsEncrypted() { + t.Error("Alice doesn't believe that the conversation is secure") + } + if !bob.IsEncrypted() { + t.Error("Bob doesn't believe that the conversation is secure") + } +} + +const ( + firstRoundTrip = iota + subsequentRoundTrip + noMACKeyCheck +) + +func roundTrip(t *testing.T, alice, bob *Conversation, message []byte, macKeyCheck int) { + alicesMessage, err := alice.Send(message) + if err != nil { + t.Errorf("Error from Alice sending message: %s", err) + } + + if len(alice.oldMACs) != 0 { + t.Errorf("Alice has not revealed all MAC keys") + } + + for i, msg := range alicesMessage { + out, encrypted, _, _, err := bob.Receive(msg) + + if err != nil { + t.Errorf("Error generated while processing test message: %s", err.Error()) + } + if len(out) > 0 { + if i != len(alicesMessage)-1 { + t.Fatal("Bob produced a message while processing a fragment of Alice's") + } + if !encrypted { + t.Errorf("Message was not marked as encrypted") + } + if !bytes.Equal(out, message) { + t.Errorf("Message corrupted: got %x, want %x", out, message) + } + } + } + + switch macKeyCheck { + case firstRoundTrip: + if len(bob.oldMACs) != 0 { + t.Errorf("Bob should not have MAC keys to reveal") + } + case subsequentRoundTrip: + if len(bob.oldMACs) != 40 { + t.Errorf("Bob has %d bytes of MAC keys to reveal, but should have 40", len(bob.oldMACs)) + } + } + + bobsMessage, err := bob.Send(message) + if err != nil { + t.Errorf("Error from Bob sending message: %s", err) + } + + if len(bob.oldMACs) != 0 { + t.Errorf("Bob has not revealed all MAC keys") + } + + for i, msg := range bobsMessage { + out, encrypted, _, _, err := alice.Receive(msg) + + if err != nil { + t.Errorf("Error generated while processing test message: %s", err.Error()) + } + if len(out) > 0 { + if i != len(bobsMessage)-1 { + t.Fatal("Alice produced a message while processing a fragment of Bob's") + } + if !encrypted { + t.Errorf("Message was not marked as encrypted") + } + if !bytes.Equal(out, message) { + t.Errorf("Message corrupted: got %x, want %x", out, message) + } + } + } + + switch macKeyCheck { + case firstRoundTrip: + if len(alice.oldMACs) != 20 { + t.Errorf("Alice has %d bytes of MAC keys to reveal, but should have 20", len(alice.oldMACs)) + } + case subsequentRoundTrip: + if len(alice.oldMACs) != 40 { + t.Errorf("Alice has %d bytes of MAC keys to reveal, but should have 40", len(alice.oldMACs)) + } + } +} + +func TestConversation(t *testing.T) { + alice, bob := setupConversation(t) + + var testMessages = [][]byte{ + []byte("hello"), []byte("bye"), + } + + roundTripType := firstRoundTrip + + for _, testMessage := range testMessages { + roundTrip(t, alice, bob, testMessage, roundTripType) + roundTripType = subsequentRoundTrip + } +} + +func TestGoodSMP(t *testing.T) { + var alice, bob Conversation + + alice.smp.secret = new(big.Int).SetInt64(42) + bob.smp.secret = alice.smp.secret + + var alicesMessages, bobsMessages []tlv + var aliceComplete, bobComplete bool + var err error + var out tlv + + alicesMessages = alice.startSMP("") + for round := 0; len(alicesMessages) > 0 || len(bobsMessages) > 0; round++ { + bobsMessages = bobsMessages[:0] + for i, msg := range alicesMessages { + out, bobComplete, err = bob.processSMP(msg) + if err != nil { + t.Errorf("Error from Bob in round %d: %s", round, err) + } + if bobComplete && i != len(alicesMessages)-1 { + t.Errorf("Bob returned a completed signal before processing all of Alice's messages in round %d", round) + } + if out.typ != 0 { + bobsMessages = append(bobsMessages, out) + } + } + + alicesMessages = alicesMessages[:0] + for i, msg := range bobsMessages { + out, aliceComplete, err = alice.processSMP(msg) + if err != nil { + t.Errorf("Error from Alice in round %d: %s", round, err) + } + if aliceComplete && i != len(bobsMessages)-1 { + t.Errorf("Alice returned a completed signal before processing all of Bob's messages in round %d", round) + } + if out.typ != 0 { + alicesMessages = append(alicesMessages, out) + } + } + } + + if !aliceComplete || !bobComplete { + t.Errorf("SMP completed without both sides reporting success: alice: %v, bob: %v\n", aliceComplete, bobComplete) + } +} + +func TestBadSMP(t *testing.T) { + var alice, bob Conversation + + alice.smp.secret = new(big.Int).SetInt64(42) + bob.smp.secret = new(big.Int).SetInt64(43) + + var alicesMessages, bobsMessages []tlv + + alicesMessages = alice.startSMP("") + for round := 0; len(alicesMessages) > 0 || len(bobsMessages) > 0; round++ { + bobsMessages = bobsMessages[:0] + for _, msg := range alicesMessages { + out, complete, _ := bob.processSMP(msg) + if complete { + t.Errorf("Bob signaled completion in round %d", round) + } + if out.typ != 0 { + bobsMessages = append(bobsMessages, out) + } + } + + alicesMessages = alicesMessages[:0] + for _, msg := range bobsMessages { + out, complete, _ := alice.processSMP(msg) + if complete { + t.Errorf("Alice signaled completion in round %d", round) + } + if out.typ != 0 { + alicesMessages = append(alicesMessages, out) + } + } + } +} + +func TestRehandshaking(t *testing.T) { + alice, bob := setupConversation(t) + roundTrip(t, alice, bob, []byte("test"), firstRoundTrip) + roundTrip(t, alice, bob, []byte("test 2"), subsequentRoundTrip) + roundTrip(t, alice, bob, []byte("test 3"), subsequentRoundTrip) + roundTrip(t, alice, bob, []byte("test 4"), subsequentRoundTrip) + roundTrip(t, alice, bob, []byte("test 5"), subsequentRoundTrip) + roundTrip(t, alice, bob, []byte("test 6"), subsequentRoundTrip) + roundTrip(t, alice, bob, []byte("test 7"), subsequentRoundTrip) + roundTrip(t, alice, bob, []byte("test 8"), subsequentRoundTrip) + performHandshake(t, alice, bob) + roundTrip(t, alice, bob, []byte("test"), noMACKeyCheck) + roundTrip(t, alice, bob, []byte("test 2"), noMACKeyCheck) +} + +func TestAgainstLibOTR(t *testing.T) { + // This test requires otr.c.test to be built as /tmp/a.out. + // If enabled, this tests runs forever performing OTR handshakes in a + // loop. + return + + alicePrivateKey, _ := hex.DecodeString(alicePrivateKeyHex) + var alice Conversation + alice.PrivateKey = new(PrivateKey) + alice.PrivateKey.Parse(alicePrivateKey) + + cmd := exec.Command("/tmp/a.out") + cmd.Stderr = os.Stderr + + out, err := cmd.StdinPipe() + if err != nil { + t.Fatal(err) + } + defer out.Close() + stdout, err := cmd.StdoutPipe() + if err != nil { + t.Fatal(err) + } + in := bufio.NewReader(stdout) + + if err := cmd.Start(); err != nil { + t.Fatal(err) + } + + out.Write([]byte(QueryMessage)) + out.Write([]byte("\n")) + var expectedText = []byte("test message") + + for { + line, isPrefix, err := in.ReadLine() + if isPrefix { + t.Fatal("line from subprocess too long") + } + if err != nil { + t.Fatal(err) + } + text, encrypted, change, alicesMessage, err := alice.Receive(line) + if err != nil { + t.Fatal(err) + } + for _, msg := range alicesMessage { + out.Write(msg) + out.Write([]byte("\n")) + } + if change == NewKeys { + alicesMessage, err := alice.Send([]byte("Go -> libotr test message")) + if err != nil { + t.Fatalf("error sending message: %s", err.Error()) + } else { + for _, msg := range alicesMessage { + out.Write(msg) + out.Write([]byte("\n")) + } + } + } + if len(text) > 0 { + if !bytes.Equal(text, expectedText) { + t.Fatalf("expected %x, but got %x", expectedText, text) + } + if !encrypted { + t.Fatal("message wasn't encrypted") + } + } + } +} diff --git a/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/smp.go b/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/smp.go new file mode 100644 index 000000000..dc6de4ee0 --- /dev/null +++ b/vendor/github.com/miekg/dns/vendor/golang.org/x/crypto/otr/smp.go @@ -0,0 +1,572 @@ +// Copyright 2012 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// This file implements the Socialist Millionaires Protocol as described in +// http://www.cypherpunks.ca/otr/Protocol-v2-3.1.0.html. The protocol +// specification is required in order to understand this code and, where +// possible, the variable names in the code match up with the spec. + +package otr + +import ( + "bytes" + "crypto/sha256" + "errors" + "hash" + "math/big" +) + +type smpFailure string + +func (s smpFailure) Error() string { + return string(s) +} + +var smpFailureError = smpFailure("otr: SMP protocol failed") +var smpSecretMissingError = smpFailure("otr: mutual secret needed") + +const smpVersion = 1 + +const ( + smpState1 = iota + smpState2 + smpState3 + smpState4 +) + +type smpState struct { + state int + a2, a3, b2, b3, pb, qb *big.Int + g2a, g3a *big.Int + g2, g3 *big.Int + g3b, papb, qaqb, ra *big.Int + saved *tlv + secret *big.Int + question string +} + +func (c *Conversation) startSMP(question string) (tlvs []tlv) { + if c.smp.state != smpState1 { + tlvs = append(tlvs, c.generateSMPAbort()) + } + tlvs = append(tlvs, c.generateSMP1(question)) + c.smp.question = "" + c.smp.state = smpState2 + return +} + +func (c *Conversation) resetSMP() { + c.smp.state = smpState1 + c.smp.secret = nil + c.smp.question = "" +} + +func (c *Conversation) processSMP(in tlv) (out tlv, complete bool, err error) { + data := in.data + + switch in.typ { + case tlvTypeSMPAbort: + if c.smp.state != smpState1 { + err = smpFailureError + } + c.resetSMP() + return + case tlvTypeSMP1WithQuestion: + // We preprocess this into a SMP1 message. + nulPos := bytes.IndexByte(data, 0) + if nulPos == -1 { + err = errors.New("otr: SMP message with question didn't contain a NUL byte") + return + } + c.smp.question = string(data[:nulPos]) + data = data[nulPos+1:] + } + + numMPIs, data, ok := getU32(data) + if !ok || numMPIs > 20 { + err = errors.New("otr: corrupt SMP message") + return + } + + mpis := make([]*big.Int, numMPIs) + for i := range mpis { + var ok bool + mpis[i], data, ok = getMPI(data) + if !ok { + err = errors.New("otr: corrupt SMP message") + return + } + } + + switch in.typ { + case tlvTypeSMP1, tlvTypeSMP1WithQuestion: + if c.smp.state != smpState1 { + c.resetSMP() + out = c.generateSMPAbort() + return + } + if c.smp.secret == nil { + err = smpSecretMissingError + return + } + if err = c.processSMP1(mpis); err != nil { + return + } + c.smp.state = smpState3 + out = c.generateSMP2() + case tlvTypeSMP2: + if c.smp.state != smpState2 { + c.resetSMP() + out = c.generateSMPAbort() + return + } + if out, err = c.processSMP2(mpis); err != nil { + out = c.generateSMPAbort() + return + } + c.smp.state = smpState4 + case tlvTypeSMP3: + if c.smp.state != smpState3 { + c.resetSMP() + out = c.generateSMPAbort() + return + } + if out, err = c.processSMP3(mpis); err != nil { + return + } + c.smp.state = smpState1 + c.smp.secret = nil + complete = true + case tlvTypeSMP4: + if c.smp.state != smpState4 { + c.resetSMP() + out = c.generateSMPAbort() + return + } + if err = c.processSMP4(mpis); err != nil { + out = c.generateSMPAbort() + return + } + c.smp.state = smpState1 + c.smp.secret = nil + complete = true + default: + panic("unknown SMP message") + } + + return +} + +func (c *Conversation) calcSMPSecret(mutualSecret []byte, weStarted bool) { + h := sha256.New() + h.Write([]byte{smpVersion}) + if weStarted { + h.Write(c.PrivateKey.PublicKey.Fingerprint()) + h.Write(c.TheirPublicKey.Fingerprint()) + } else { + h.Write(c.TheirPublicKey.Fingerprint()) + h.Write(c.PrivateKey.PublicKey.Fingerprint()) + } + h.Write(c.SSID[:]) + h.Write(mutualSecret) + c.smp.secret = new(big.Int).SetBytes(h.Sum(nil)) +} + +func (c *Conversation) generateSMP1(question string) tlv { + var randBuf [16]byte + c.smp.a2 = c.randMPI(randBuf[:]) + c.smp.a3 = c.randMPI(randBuf[:]) + g2a := new(big.Int).Exp(g, c.smp.a2, p) + g3a := new(big.Int).Exp(g, c.smp.a3, p) + h := sha256.New() + + r2 := c.randMPI(randBuf[:]) + r := new(big.Int).Exp(g, r2, p) + c2 := new(big.Int).SetBytes(hashMPIs(h, 1, r)) + d2 := new(big.Int).Mul(c.smp.a2, c2) + d2.Sub(r2, d2) + d2.Mod(d2, q) + if d2.Sign() < 0 { + d2.Add(d2, q) + } + + r3 := c.randMPI(randBuf[:]) + r.Exp(g, r3, p) + c3 := new(big.Int).SetBytes(hashMPIs(h, 2, r)) + d3 := new(big.Int).Mul(c.smp.a3, c3) + d3.Sub(r3, d3) + d3.Mod(d3, q) + if d3.Sign() < 0 { + d3.Add(d3, q) + } + + var ret tlv + if len(question) > 0 { + ret.typ = tlvTypeSMP1WithQuestion + ret.data = append(ret.data, question...) + ret.data = append(ret.data, 0) + } else { + ret.typ = tlvTypeSMP1 + } + ret.data = appendU32(ret.data, 6) + ret.data = appendMPIs(ret.data, g2a, c2, d2, g3a, c3, d3) + return ret +} + +func (c *Conversation) processSMP1(mpis []*big.Int) error { + if len(mpis) != 6 { + return errors.New("otr: incorrect number of arguments in SMP1 message") + } + g2a := mpis[0] + c2 := mpis[1] + d2 := mpis[2] + g3a := mpis[3] + c3 := mpis[4] + d3 := mpis[5] + h := sha256.New() + + r := new(big.Int).Exp(g, d2, p) + s := new(big.Int).Exp(g2a, c2, p) + r.Mul(r, s) + r.Mod(r, p) + t := new(big.Int).SetBytes(hashMPIs(h, 1, r)) + if c2.Cmp(t) != 0 { + return errors.New("otr: ZKP c2 incorrect in SMP1 message") + } + r.Exp(g, d3, p) + s.Exp(g3a, c3, p) + r.Mul(r, s) + r.Mod(r, p) + t.SetBytes(hashMPIs(h, 2, r)) + if c3.Cmp(t) != 0 { + return errors.New("otr: ZKP c3 incorrect in SMP1 message") + } + + c.smp.g2a = g2a + c.smp.g3a = g3a + return nil +} + +func (c *Conversation) generateSMP2() tlv { + var randBuf [16]byte + b2 := c.randMPI(randBuf[:]) + c.smp.b3 = c.randMPI(randBuf[:]) + r2 := c.randMPI(randBuf[:]) + r3 := c.randMPI(randBuf[:]) + r4 := c.randMPI(randBuf[:]) + r5 := c.randMPI(randBuf[:]) + r6 := c.randMPI(randBuf[:]) + + g2b := new(big.Int).Exp(g, b2, p) + g3b := new(big.Int).Exp(g, c.smp.b3, p) + + r := new(big.Int).Exp(g, r2, p) + h := sha256.New() + c2 := new(big.Int).SetBytes(hashMPIs(h, 3, r)) + d2 := new(big.Int).Mul(b2, c2) + d2.Sub(r2, d2) + d2.Mod(d2, q) + if d2.Sign() < 0 { + d2.Add(d2, q) + } + + r.Exp(g, r3, p) + c3 := new(big.Int).SetBytes(hashMPIs(h, 4, r)) + d3 := new(big.Int).Mul(c.smp.b3, c3) + d3.Sub(r3, d3) + d3.Mod(d3, q) + if d3.Sign() < 0 { + d3.Add(d3, q) + } + + c.smp.g2 = new(big.Int).Exp(c.smp.g2a, b2, p) + c.smp.g3 = new(big.Int).Exp(c.smp.g3a, c.smp.b3, p) + c.smp.pb = new(big.Int).Exp(c.smp.g3, r4, p) + c.smp.qb = new(big.Int).Exp(g, r4, p) + r.Exp(c.smp.g2, c.smp.secret, p) + c.smp.qb.Mul(c.smp.qb, r) + c.smp.qb.Mod(c.smp.qb, p) + + s := new(big.Int) + s.Exp(c.smp.g2, r6, p) + r.Exp(g, r5, p) + s.Mul(r, s) + s.Mod(s, p) + r.Exp(c.smp.g3, r5, p) + cp := new(big.Int).SetBytes(hashMPIs(h, 5, r, s)) + + // D5 = r5 - r4 cP mod q and D6 = r6 - y cP mod q + + s.Mul(r4, cp) + r.Sub(r5, s) + d5 := new(big.Int).Mod(r, q) + if d5.Sign() < 0 { + d5.Add(d5, q) + } + + s.Mul(c.smp.secret, cp) + r.Sub(r6, s) + d6 := new(big.Int).Mod(r, q) + if d6.Sign() < 0 { + d6.Add(d6, q) + } + + var ret tlv + ret.typ = tlvTypeSMP2 + ret.data = appendU32(ret.data, 11) + ret.data = appendMPIs(ret.data, g2b, c2, d2, g3b, c3, d3, c.smp.pb, c.smp.qb, cp, d5, d6) + return ret +} + +func (c *Conversation) processSMP2(mpis []*big.Int) (out tlv, err error) { + if len(mpis) != 11 { + err = errors.New("otr: incorrect number of arguments in SMP2 message") + return + } + g2b := mpis[0] + c2 := mpis[1] + d2 := mpis[2] + g3b := mpis[3] + c3 := mpis[4] + d3 := mpis[5] + pb := mpis[6] + qb := mpis[7] + cp := mpis[8] + d5 := mpis[9] + d6 := mpis[10] + h := sha256.New() + + r := new(big.Int).Exp(g, d2, p) + s := new(big.Int).Exp(g2b, c2, p) + r.Mul(r, s) + r.Mod(r, p) + s.SetBytes(hashMPIs(h, 3, r)) + if c2.Cmp(s) != 0 { + err = errors.New("otr: ZKP c2 failed in SMP2 message") + return + } + + r.Exp(g, d3, p) + s.Exp(g3b, c3, p) + r.Mul(r, s) + r.Mod(r, p) + s.SetBytes(hashMPIs(h, 4, r)) + if c3.Cmp(s) != 0 { + err = errors.New("otr: ZKP c3 failed in SMP2 message") + return + } + + c.smp.g2 = new(big.Int).Exp(g2b, c.smp.a2, p) + c.smp.g3 = new(big.Int).Exp(g3b, c.smp.a3, p) + + r.Exp(g, d5, p) + s.Exp(c.smp.g2, d6, p) + r.Mul(r, s) + s.Exp(qb, cp, p) + r.Mul(r, s) + r.Mod(r, p) + + s.Exp(c.smp.g3, d5, p) + t := new(big.Int).Exp(pb, cp, p) + s.Mul(s, t) + s.Mod(s, p) + t.SetBytes(hashMPIs(h, 5, s, r)) + if cp.Cmp(t) != 0 { + err = errors.New("otr: ZKP cP failed in SMP2 message") + return + } + + var randBuf [16]byte + r4 := c.randMPI(randBuf[:]) + r5 := c.randMPI(randBuf[:]) + r6 := c.randMPI(randBuf[:]) + r7 := c.randMPI(randBuf[:]) + + pa := new(big.Int).Exp(c.smp.g3, r4, p) + r.Exp(c.smp.g2, c.smp.secret, p) + qa := new(big.Int).Exp(g, r4, p) + qa.Mul(qa, r) + qa.Mod(qa, p) + + r.Exp(g, r5, p) + s.Exp(c.smp.g2, r6, p) + r.Mul(r, s) + r.Mod(r, p) + + s.Exp(c.smp.g3, r5, p) + cp.SetBytes(hashMPIs(h, 6, s, r)) + + r.Mul(r4, cp) + d5 = new(big.Int).Sub(r5, r) + d5.Mod(d5, q) + if d5.Sign() < 0 { + d5.Add(d5, q) + } + + r.Mul(c.smp.secret, cp) + d6 = new(big.Int).Sub(r6, r) + d6.Mod(d6, q) + if d6.Sign() < 0 { + d6.Add(d6, q) + } + + r.ModInverse(qb, p) + qaqb := new(big.Int).Mul(qa, r) + qaqb.Mod(qaqb, p) + + ra := new(big.Int).Exp(qaqb, c.smp.a3, p) + r.Exp(qaqb, r7, p) + s.Exp(g, r7, p) + cr := new(big.Int).SetBytes(hashMPIs(h, 7, s, r)) + + r.Mul(c.smp.a3, cr) + d7 := new(big.Int).Sub(r7, r) + d7.Mod(d7, q) + if d7.Sign() < 0 { + d7.Add(d7, q) + } + + c.smp.g3b = g3b + c.smp.qaqb = qaqb + + r.ModInverse(pb, p) + c.smp.papb = new(big.Int).Mul(pa, r) + c.smp.papb.Mod(c.smp.papb, p) + c.smp.ra = ra + + out.typ = tlvTypeSMP3 + out.data = appendU32(out.data, 8) + out.data = appendMPIs(out.data, pa, qa, cp, d5, d6, ra, cr, d7) + return +} + +func (c *Conversation) processSMP3(mpis []*big.Int) (out tlv, err error) { + if len(mpis) != 8 { + err = errors.New("otr: incorrect number of arguments in SMP3 message") + return + } + pa := mpis[0] + qa := mpis[1] + cp := mpis[2] + d5 := mpis[3] + d6 := mpis[4] + ra := mpis[5] + cr := mpis[6] + d7 := mpis[7] + h := sha256.New() + + r := new(big.Int).Exp(g, d5, p) + s := new(big.Int).Exp(c.smp.g2, d6, p) + r.Mul(r, s) + s.Exp(qa, cp, p) + r.Mul(r, s) + r.Mod(r, p) + + s.Exp(c.smp.g3, d5, p) + t := new(big.Int).Exp(pa, cp, p) + s.Mul(s, t) + s.Mod(s, p) + t.SetBytes(hashMPIs(h, 6, s, r)) + if t.Cmp(cp) != 0 { + err = errors.New("otr: ZKP cP failed in SMP3 message") + return + } + + r.ModInverse(c.smp.qb, p) + qaqb := new(big.Int).Mul(qa, r) + qaqb.Mod(qaqb, p) + + r.Exp(qaqb, d7, p) + s.Exp(ra, cr, p) + r.Mul(r, s) + r.Mod(r, p) + + s.Exp(g, d7, p) + t.Exp(c.smp.g3a, cr, p) + s.Mul(s, t) + s.Mod(s, p) + t.SetBytes(hashMPIs(h, 7, s, r)) + if t.Cmp(cr) != 0 { + err = errors.New("otr: ZKP cR failed in SMP3 message") + return + } + + var randBuf [16]byte + r7 := c.randMPI(randBuf[:]) + rb := new(big.Int).Exp(qaqb, c.smp.b3, p) + + r.Exp(qaqb, r7, p) + s.Exp(g, r7, p) + cr = new(big.Int).SetBytes(hashMPIs(h, 8, s, r)) + + r.Mul(c.smp.b3, cr) + d7 = new(big.Int).Sub(r7, r) + d7.Mod(d7, q) + if d7.Sign() < 0 { + d7.Add(d7, q) + } + + out.typ = tlvTypeSMP4 + out.data = appendU32(out.data, 3) + out.data = appendMPIs(out.data, rb, cr, d7) + + r.ModInverse(c.smp.pb, p) + r.Mul(pa, r) + r.Mod(r, p) + s.Exp(ra, c.smp.b3, p) + if r.Cmp(s) != 0 { + err = smpFailureError + } + + return +} + +func (c *Conversation) processSMP4(mpis []*big.Int) error { + if len(mpis) != 3 { + return errors.New("otr: incorrect number of arguments in SMP4 message") + } + rb := mpis[0] + cr := mpis[1] + d7 := mpis[2] + h := sha256.New() + + r := new(big.Int).Exp(c.smp.qaqb, d7, p) + s := new(big.Int).Exp(rb, cr, p) + r.Mul(r, s) + r.Mod(r, p) + + s.Exp(g, d7, p) + t := new(big.Int).Exp(c.smp.g3b, cr, p) + s.Mul(s, t) + s.Mod(s, p) + t.SetBytes(hashMPIs(h, 8, s, r)) + if t.Cmp(cr) != 0 { + return errors.New("otr: ZKP cR failed in SMP4 message") + } + + r.Exp(rb, c.smp.a3, p) + if r.Cmp(c.smp.papb) != 0 { + return smpFailureError + } + + return nil +} + +func (c *Conversation) generateSMPAbort() tlv { + return tlv{typ: tlvTypeSMPAbort} +} + +func hashMPIs(h hash.Hash, magic byte, mpis ...*big.Int) []byte { + if h != nil { + h.Reset() + } else { + h = sha256.New() + } + + h.Write([]byte{magic}) + for _, mpi := range mpis { + h.Write(appendMPI(nil, mpi)) + } + return h.Sum(nil) +} |