diff options
Diffstat (limited to 'vendor/golang.org/x/crypto/poly1305/poly1305.go')
| -rw-r--r-- | vendor/golang.org/x/crypto/poly1305/poly1305.go | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/vendor/golang.org/x/crypto/poly1305/poly1305.go b/vendor/golang.org/x/crypto/poly1305/poly1305.go index 066159b7..9d7a6af0 100644 --- a/vendor/golang.org/x/crypto/poly1305/poly1305.go +++ b/vendor/golang.org/x/crypto/poly1305/poly1305.go @@ -26,7 +26,9 @@ const TagSize = 16 // 16-byte result into out. Authenticating two different messages with the same // key allows an attacker to forge messages at will. func Sum(out *[16]byte, m []byte, key *[32]byte) { - sum(out, m, key) + h := New(key) + h.Write(m) + h.Sum(out[:0]) } // Verify returns true if mac is a valid authenticator for m with the given key. @@ -46,10 +48,9 @@ func Verify(mac *[16]byte, m []byte, key *[32]byte) bool { // two different messages with the same key allows an attacker // to forge messages at will. func New(key *[32]byte) *MAC { - return &MAC{ - mac: newMAC(key), - finalized: false, - } + m := &MAC{} + initialize(key, &m.macState) + return m } // MAC is an io.Writer computing an authentication tag @@ -58,7 +59,7 @@ func New(key *[32]byte) *MAC { // MAC cannot be used like common hash.Hash implementations, // because using a poly1305 key twice breaks its security. // Therefore writing data to a running MAC after calling -// Sum causes it to panic. +// Sum or Verify causes it to panic. type MAC struct { mac // platform-dependent implementation @@ -71,10 +72,10 @@ func (h *MAC) Size() int { return TagSize } // Write adds more data to the running message authentication code. // It never returns an error. // -// It must not be called after the first call of Sum. +// It must not be called after the first call of Sum or Verify. func (h *MAC) Write(p []byte) (n int, err error) { if h.finalized { - panic("poly1305: write to MAC after Sum") + panic("poly1305: write to MAC after Sum or Verify") } return h.mac.Write(p) } @@ -87,3 +88,12 @@ func (h *MAC) Sum(b []byte) []byte { h.finalized = true return append(b, mac[:]...) } + +// Verify returns whether the authenticator of all data written to +// the message authentication code matches the expected value. +func (h *MAC) Verify(expected []byte) bool { + var mac [TagSize]byte + h.mac.Sum(&mac) + h.finalized = true + return subtle.ConstantTimeCompare(expected, mac[:]) == 1 +} |