diff options
Diffstat (limited to 'vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go')
-rw-r--r-- | vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go b/vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go new file mode 100644 index 000000000..f7e4bfb1c --- /dev/null +++ b/vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go @@ -0,0 +1,70 @@ +// Copyright 2016 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 chacha20poly1305 + +import ( + "encoding/binary" + + "golang.org/x/crypto/chacha20poly1305/internal/chacha20" + "golang.org/x/crypto/poly1305" +) + +func roundTo16(n int) int { + return 16 * ((n + 15) / 16) +} + +func (c *chacha20poly1305) sealGeneric(dst, nonce, plaintext, additionalData []byte) []byte { + var counter [16]byte + copy(counter[4:], nonce) + + var polyKey [32]byte + chacha20.XORKeyStream(polyKey[:], polyKey[:], &counter, &c.key) + + ret, out := sliceForAppend(dst, len(plaintext)+poly1305.TagSize) + counter[0] = 1 + chacha20.XORKeyStream(out, plaintext, &counter, &c.key) + + polyInput := make([]byte, roundTo16(len(additionalData))+roundTo16(len(plaintext))+8+8) + copy(polyInput, additionalData) + copy(polyInput[roundTo16(len(additionalData)):], out[:len(plaintext)]) + binary.LittleEndian.PutUint64(polyInput[len(polyInput)-16:], uint64(len(additionalData))) + binary.LittleEndian.PutUint64(polyInput[len(polyInput)-8:], uint64(len(plaintext))) + + var tag [poly1305.TagSize]byte + poly1305.Sum(&tag, polyInput, &polyKey) + copy(out[len(plaintext):], tag[:]) + + return ret +} + +func (c *chacha20poly1305) openGeneric(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) { + var tag [poly1305.TagSize]byte + copy(tag[:], ciphertext[len(ciphertext)-16:]) + ciphertext = ciphertext[:len(ciphertext)-16] + + var counter [16]byte + copy(counter[4:], nonce) + + var polyKey [32]byte + chacha20.XORKeyStream(polyKey[:], polyKey[:], &counter, &c.key) + + polyInput := make([]byte, roundTo16(len(additionalData))+roundTo16(len(ciphertext))+8+8) + copy(polyInput, additionalData) + copy(polyInput[roundTo16(len(additionalData)):], ciphertext) + binary.LittleEndian.PutUint64(polyInput[len(polyInput)-16:], uint64(len(additionalData))) + binary.LittleEndian.PutUint64(polyInput[len(polyInput)-8:], uint64(len(ciphertext))) + + ret, out := sliceForAppend(dst, len(ciphertext)) + if !poly1305.Verify(&tag, polyInput, &polyKey) { + for i := range out { + out[i] = 0 + } + return nil, errOpen + } + + counter[0] = 1 + chacha20.XORKeyStream(out, ciphertext, &counter, &c.key) + return ret, nil +} |