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Fix data race, remember when signing key has been masked

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This commit is contained in:
Alexander Neumann 2015-04-26 13:07:26 +02:00
parent 2e46914d0c
commit 5ab900acac
1 changed files with 10 additions and 2 deletions
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12
crypto/crypto.go
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@ -47,6 +47,8 @@ type EncryptionKey [32]byte
type SigningKey struct { type SigningKey struct {
K [16]byte `json:"k"` // for AES128 K [16]byte `json:"k"` // for AES128
R [16]byte `json:"r"` // for Poly1305 R [16]byte `json:"r"` // for Poly1305
masked bool // remember if the signing key has already been masked
} }
// mask for key, (cf. http://cr.yp.to/mac/poly1305-20050329.pdf) // mask for key, (cf. http://cr.yp.to/mac/poly1305-20050329.pdf)
@ -75,7 +77,9 @@ func poly1305Sign(msg []byte, nonce []byte, key *SigningKey) []byte {
var k [32]byte var k [32]byte
// make sure key is masked // make sure key is masked
maskKey(key) if !key.masked {
maskKey(key)
}
// fill in nonce, encrypted with AES and key[:16] // fill in nonce, encrypted with AES and key[:16]
cipher, err := aes.NewCipher(key.K[:]) cipher, err := aes.NewCipher(key.K[:])
@ -102,6 +106,8 @@ func maskKey(k *SigningKey) {
for i := 0; i < poly1305.TagSize; i++ { for i := 0; i < poly1305.TagSize; i++ {
k.R[i] = k.R[i] & poly1305KeyMask[i] k.R[i] = k.R[i] & poly1305KeyMask[i]
} }
k.masked = true
} }
// construct mac key from slice (k||r), with masking // construct mac key from slice (k||r), with masking
@ -117,7 +123,9 @@ func poly1305Verify(msg []byte, nonce []byte, key *SigningKey, mac []byte) bool
var k [32]byte var k [32]byte
// make sure key is masked // make sure key is masked
maskKey(key) if !key.masked {
maskKey(key)
}
// fill in nonce, encrypted with AES and key[:16] // fill in nonce, encrypted with AES and key[:16]
cipher, err := aes.NewCipher(key.K[:]) cipher, err := aes.NewCipher(key.K[:])