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Diffstat (limited to 'Godeps/_workspace/src/golang.org/x/crypto/bcrypt/bcrypt.go')
-rw-r--r-- | Godeps/_workspace/src/golang.org/x/crypto/bcrypt/bcrypt.go | 294 |
1 files changed, 294 insertions, 0 deletions
diff --git a/Godeps/_workspace/src/golang.org/x/crypto/bcrypt/bcrypt.go b/Godeps/_workspace/src/golang.org/x/crypto/bcrypt/bcrypt.go new file mode 100644 index 000000000..b8e18d744 --- /dev/null +++ b/Godeps/_workspace/src/golang.org/x/crypto/bcrypt/bcrypt.go @@ -0,0 +1,294 @@ +// Copyright 2011 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 bcrypt implements Provos and Mazières's bcrypt adaptive hashing +// algorithm. See http://www.usenix.org/event/usenix99/provos/provos.pdf +package bcrypt + +// The code is a port of Provos and Mazières's C implementation. +import ( + "crypto/rand" + "crypto/subtle" + "errors" + "fmt" + "golang.org/x/crypto/blowfish" + "io" + "strconv" +) + +const ( + MinCost int = 4 // the minimum allowable cost as passed in to GenerateFromPassword + MaxCost int = 31 // the maximum allowable cost as passed in to GenerateFromPassword + DefaultCost int = 10 // the cost that will actually be set if a cost below MinCost is passed into GenerateFromPassword +) + +// The error returned from CompareHashAndPassword when a password and hash do +// not match. +var ErrMismatchedHashAndPassword = errors.New("crypto/bcrypt: hashedPassword is not the hash of the given password") + +// The error returned from CompareHashAndPassword when a hash is too short to +// be a bcrypt hash. +var ErrHashTooShort = errors.New("crypto/bcrypt: hashedSecret too short to be a bcrypted password") + +// The error returned from CompareHashAndPassword when a hash was created with +// a bcrypt algorithm newer than this implementation. +type HashVersionTooNewError byte + +func (hv HashVersionTooNewError) Error() string { + return fmt.Sprintf("crypto/bcrypt: bcrypt algorithm version '%c' requested is newer than current version '%c'", byte(hv), majorVersion) +} + +// The error returned from CompareHashAndPassword when a hash starts with something other than '$' +type InvalidHashPrefixError byte + +func (ih InvalidHashPrefixError) Error() string { + return fmt.Sprintf("crypto/bcrypt: bcrypt hashes must start with '$', but hashedSecret started with '%c'", byte(ih)) +} + +type InvalidCostError int + +func (ic InvalidCostError) Error() string { + return fmt.Sprintf("crypto/bcrypt: cost %d is outside allowed range (%d,%d)", int(ic), int(MinCost), int(MaxCost)) +} + +const ( + majorVersion = '2' + minorVersion = 'a' + maxSaltSize = 16 + maxCryptedHashSize = 23 + encodedSaltSize = 22 + encodedHashSize = 31 + minHashSize = 59 +) + +// magicCipherData is an IV for the 64 Blowfish encryption calls in +// bcrypt(). It's the string "OrpheanBeholderScryDoubt" in big-endian bytes. +var magicCipherData = []byte{ + 0x4f, 0x72, 0x70, 0x68, + 0x65, 0x61, 0x6e, 0x42, + 0x65, 0x68, 0x6f, 0x6c, + 0x64, 0x65, 0x72, 0x53, + 0x63, 0x72, 0x79, 0x44, + 0x6f, 0x75, 0x62, 0x74, +} + +type hashed struct { + hash []byte + salt []byte + cost int // allowed range is MinCost to MaxCost + major byte + minor byte +} + +// GenerateFromPassword returns the bcrypt hash of the password at the given +// cost. If the cost given is less than MinCost, the cost will be set to +// DefaultCost, instead. Use CompareHashAndPassword, as defined in this package, +// to compare the returned hashed password with its cleartext version. +func GenerateFromPassword(password []byte, cost int) ([]byte, error) { + p, err := newFromPassword(password, cost) + if err != nil { + return nil, err + } + return p.Hash(), nil +} + +// CompareHashAndPassword compares a bcrypt hashed password with its possible +// plaintext equivalent. Returns nil on success, or an error on failure. +func CompareHashAndPassword(hashedPassword, password []byte) error { + p, err := newFromHash(hashedPassword) + if err != nil { + return err + } + + otherHash, err := bcrypt(password, p.cost, p.salt) + if err != nil { + return err + } + + otherP := &hashed{otherHash, p.salt, p.cost, p.major, p.minor} + if subtle.ConstantTimeCompare(p.Hash(), otherP.Hash()) == 1 { + return nil + } + + return ErrMismatchedHashAndPassword +} + +// Cost returns the hashing cost used to create the given hashed +// password. When, in the future, the hashing cost of a password system needs +// to be increased in order to adjust for greater computational power, this +// function allows one to establish which passwords need to be updated. +func Cost(hashedPassword []byte) (int, error) { + p, err := newFromHash(hashedPassword) + if err != nil { + return 0, err + } + return p.cost, nil +} + +func newFromPassword(password []byte, cost int) (*hashed, error) { + if cost < MinCost { + cost = DefaultCost + } + p := new(hashed) + p.major = majorVersion + p.minor = minorVersion + + err := checkCost(cost) + if err != nil { + return nil, err + } + p.cost = cost + + unencodedSalt := make([]byte, maxSaltSize) + _, err = io.ReadFull(rand.Reader, unencodedSalt) + if err != nil { + return nil, err + } + + p.salt = base64Encode(unencodedSalt) + hash, err := bcrypt(password, p.cost, p.salt) + if err != nil { + return nil, err + } + p.hash = hash + return p, err +} + +func newFromHash(hashedSecret []byte) (*hashed, error) { + if len(hashedSecret) < minHashSize { + return nil, ErrHashTooShort + } + p := new(hashed) + n, err := p.decodeVersion(hashedSecret) + if err != nil { + return nil, err + } + hashedSecret = hashedSecret[n:] + n, err = p.decodeCost(hashedSecret) + if err != nil { + return nil, err + } + hashedSecret = hashedSecret[n:] + + // The "+2" is here because we'll have to append at most 2 '=' to the salt + // when base64 decoding it in expensiveBlowfishSetup(). + p.salt = make([]byte, encodedSaltSize, encodedSaltSize+2) + copy(p.salt, hashedSecret[:encodedSaltSize]) + + hashedSecret = hashedSecret[encodedSaltSize:] + p.hash = make([]byte, len(hashedSecret)) + copy(p.hash, hashedSecret) + + return p, nil +} + +func bcrypt(password []byte, cost int, salt []byte) ([]byte, error) { + cipherData := make([]byte, len(magicCipherData)) + copy(cipherData, magicCipherData) + + c, err := expensiveBlowfishSetup(password, uint32(cost), salt) + if err != nil { + return nil, err + } + + for i := 0; i < 24; i += 8 { + for j := 0; j < 64; j++ { + c.Encrypt(cipherData[i:i+8], cipherData[i:i+8]) + } + } + + // Bug compatibility with C bcrypt implementations. We only encode 23 of + // the 24 bytes encrypted. + hsh := base64Encode(cipherData[:maxCryptedHashSize]) + return hsh, nil +} + +func expensiveBlowfishSetup(key []byte, cost uint32, salt []byte) (*blowfish.Cipher, error) { + + csalt, err := base64Decode(salt) + if err != nil { + return nil, err + } + + // Bug compatibility with C bcrypt implementations. They use the trailing + // NULL in the key string during expansion. + ckey := append(key, 0) + + c, err := blowfish.NewSaltedCipher(ckey, csalt) + if err != nil { + return nil, err + } + + var i, rounds uint64 + rounds = 1 << cost + for i = 0; i < rounds; i++ { + blowfish.ExpandKey(ckey, c) + blowfish.ExpandKey(csalt, c) + } + + return c, nil +} + +func (p *hashed) Hash() []byte { + arr := make([]byte, 60) + arr[0] = '$' + arr[1] = p.major + n := 2 + if p.minor != 0 { + arr[2] = p.minor + n = 3 + } + arr[n] = '$' + n += 1 + copy(arr[n:], []byte(fmt.Sprintf("%02d", p.cost))) + n += 2 + arr[n] = '$' + n += 1 + copy(arr[n:], p.salt) + n += encodedSaltSize + copy(arr[n:], p.hash) + n += encodedHashSize + return arr[:n] +} + +func (p *hashed) decodeVersion(sbytes []byte) (int, error) { + if sbytes[0] != '$' { + return -1, InvalidHashPrefixError(sbytes[0]) + } + if sbytes[1] > majorVersion { + return -1, HashVersionTooNewError(sbytes[1]) + } + p.major = sbytes[1] + n := 3 + if sbytes[2] != '$' { + p.minor = sbytes[2] + n++ + } + return n, nil +} + +// sbytes should begin where decodeVersion left off. +func (p *hashed) decodeCost(sbytes []byte) (int, error) { + cost, err := strconv.Atoi(string(sbytes[0:2])) + if err != nil { + return -1, err + } + err = checkCost(cost) + if err != nil { + return -1, err + } + p.cost = cost + return 3, nil +} + +func (p *hashed) String() string { + return fmt.Sprintf("&{hash: %#v, salt: %#v, cost: %d, major: %c, minor: %c}", string(p.hash), p.salt, p.cost, p.major, p.minor) +} + +func checkCost(cost int) error { + if cost < MinCost || cost > MaxCost { + return InvalidCostError(cost) + } + return nil +} |