diff options
Diffstat (limited to 'src/vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go')
-rw-r--r-- | src/vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/src/vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go b/src/vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go new file mode 100644 index 0000000..6313898 --- /dev/null +++ b/src/vendor/golang.org/x/crypto/chacha20poly1305/chacha20poly1305_generic.go @@ -0,0 +1,81 @@ +// 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/chacha20" + "golang.org/x/crypto/internal/alias" + "golang.org/x/crypto/internal/poly1305" +) + +func writeWithPadding(p *poly1305.MAC, b []byte) { + p.Write(b) + if rem := len(b) % 16; rem != 0 { + var buf [16]byte + padLen := 16 - rem + p.Write(buf[:padLen]) + } +} + +func writeUint64(p *poly1305.MAC, n int) { + var buf [8]byte + binary.LittleEndian.PutUint64(buf[:], uint64(n)) + p.Write(buf[:]) +} + +func (c *chacha20poly1305) sealGeneric(dst, nonce, plaintext, additionalData []byte) []byte { + ret, out := sliceForAppend(dst, len(plaintext)+poly1305.TagSize) + ciphertext, tag := out[:len(plaintext)], out[len(plaintext):] + if alias.InexactOverlap(out, plaintext) { + panic("chacha20poly1305: invalid buffer overlap") + } + + var polyKey [32]byte + s, _ := chacha20.NewUnauthenticatedCipher(c.key[:], nonce) + s.XORKeyStream(polyKey[:], polyKey[:]) + s.SetCounter(1) // set the counter to 1, skipping 32 bytes + s.XORKeyStream(ciphertext, plaintext) + + p := poly1305.New(&polyKey) + writeWithPadding(p, additionalData) + writeWithPadding(p, ciphertext) + writeUint64(p, len(additionalData)) + writeUint64(p, len(plaintext)) + p.Sum(tag[:0]) + + return ret +} + +func (c *chacha20poly1305) openGeneric(dst, nonce, ciphertext, additionalData []byte) ([]byte, error) { + tag := ciphertext[len(ciphertext)-16:] + ciphertext = ciphertext[:len(ciphertext)-16] + + var polyKey [32]byte + s, _ := chacha20.NewUnauthenticatedCipher(c.key[:], nonce) + s.XORKeyStream(polyKey[:], polyKey[:]) + s.SetCounter(1) // set the counter to 1, skipping 32 bytes + + p := poly1305.New(&polyKey) + writeWithPadding(p, additionalData) + writeWithPadding(p, ciphertext) + writeUint64(p, len(additionalData)) + writeUint64(p, len(ciphertext)) + + ret, out := sliceForAppend(dst, len(ciphertext)) + if alias.InexactOverlap(out, ciphertext) { + panic("chacha20poly1305: invalid buffer overlap") + } + if !p.Verify(tag) { + for i := range out { + out[i] = 0 + } + return nil, errOpen + } + + s.XORKeyStream(out, ciphertext) + return ret, nil +} |