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crypto/tls: support ChaCha20-Poly1305.

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This change adds support for the ChaCha20-Poly1305 AEAD to crypto/tls,
as specified in https://tools.ietf.org/html/rfc7905.

Fixes #15499.

Change-Id: Iaa689be90e03f208c40b574eca399e56f3c7ecf1
Reviewed-on: https://go-review.googlesource.com/30957
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Adam Langley 2016-10-12 10:46:43 -07:00
parent 53121dd61c
commit 7f2a0090ec
6 changed files with 273 additions and 11 deletions
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68
cipher_suites.go
View file

@ -14,6 +14,8 @@ import (
"crypto/sha256"
"crypto/x509"
"hash"
"golang_org/x/crypto/chacha20poly1305"
)
// a keyAgreement implements the client and server side of a TLS key agreement
@ -75,7 +77,9 @@ type cipherSuite struct {
var cipherSuites = []*cipherSuite{
// Ciphersuite order is chosen so that ECDHE comes before plain RSA and
// GCM is top preference.
// AEADs are the top preference.
{TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteDefaultOff, nil, nil, aeadChaCha20Poly1305},
{TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305, 32, 0, 12, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12 | suiteDefaultOff, nil, nil, aeadChaCha20Poly1305},
{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12, nil, nil, aeadAESGCM},
{TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, 16, 0, 4, ecdheECDSAKA, suiteECDHE | suiteECDSA | suiteTLS12, nil, nil, aeadAESGCM},
{TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, 32, 0, 4, ecdheRSAKA, suiteECDHE | suiteTLS12 | suiteSHA384, nil, nil, aeadAESGCM},
@ -145,6 +149,15 @@ type macFunction interface {
MAC(digestBuf, seq, header, data, extra []byte) []byte
}
type aead interface {
cipher.AEAD
// explicitIVLen returns the number of bytes used by the explicit nonce
// that is included in the record. This is eight for older AEADs and
// zero for modern ones.
explicitNonceLen() int
}
// fixedNonceAEAD wraps an AEAD and prefixes a fixed portion of the nonce to
// each call.
type fixedNonceAEAD struct {
@ -155,8 +168,9 @@ type fixedNonceAEAD struct {
aead cipher.AEAD
}
func (f *fixedNonceAEAD) NonceSize() int { return 8 }
func (f *fixedNonceAEAD) Overhead() int { return f.aead.Overhead() }
func (f *fixedNonceAEAD) NonceSize() int { return 8 }
func (f *fixedNonceAEAD) Overhead() int { return f.aead.Overhead() }
func (f *fixedNonceAEAD) explicitNonceLen() int { return 8 }
func (f *fixedNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
copy(f.sealNonce[len(f.sealNonce)-8:], nonce)
@ -168,6 +182,41 @@ func (f *fixedNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]b
return f.aead.Open(out, f.openNonce, plaintext, additionalData)
}
// xoredNonceAEAD wraps an AEAD by XORing in a fixed pattern to the nonce
// before each call.
type xorNonceAEAD struct {
nonceMask [12]byte
aead cipher.AEAD
}
func (f *xorNonceAEAD) NonceSize() int { return 8 }
func (f *xorNonceAEAD) Overhead() int { return f.aead.Overhead() }
func (f *xorNonceAEAD) explicitNonceLen() int { return 0 }
func (f *xorNonceAEAD) Seal(out, nonce, plaintext, additionalData []byte) []byte {
for i, b := range nonce {
f.nonceMask[4+i] ^= b
}
result := f.aead.Seal(out, f.nonceMask[:], plaintext, additionalData)
for i, b := range nonce {
f.nonceMask[4+i] ^= b
}
return result
}
func (f *xorNonceAEAD) Open(out, nonce, plaintext, additionalData []byte) ([]byte, error) {
for i, b := range nonce {
f.nonceMask[4+i] ^= b
}
result, err := f.aead.Open(out, f.nonceMask[:], plaintext, additionalData)
for i, b := range nonce {
f.nonceMask[4+i] ^= b
}
return result, err
}
func aeadAESGCM(key, fixedNonce []byte) cipher.AEAD {
aes, err := aes.NewCipher(key)
if err != nil {
@ -185,6 +234,17 @@ func aeadAESGCM(key, fixedNonce []byte) cipher.AEAD {
return &fixedNonceAEAD{nonce1, nonce2, aead}
}
func aeadChaCha20Poly1305(key, fixedNonce []byte) cipher.AEAD {
aead, err := chacha20poly1305.New(key)
if err != nil {
panic(err)
}
ret := &xorNonceAEAD{aead: aead}
copy(ret.nonceMask[:], fixedNonce)
return ret
}
// ssl30MAC implements the SSLv3 MAC function, as defined in
// www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt section 5.2.3.1
type ssl30MAC struct {
@ -330,6 +390,8 @@ const (
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 uint16 = 0xc02b
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc030
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 uint16 = 0xc02c
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca8
TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 uint16 = 0xcca9
// TLS_FALLBACK_SCSV isn't a standard cipher suite but an indicator
// that the client is doing version fallback. See