diff options
Diffstat (limited to 'src/pkg/crypto/hmac/hmac.go')
-rw-r--r-- | src/pkg/crypto/hmac/hmac.go | 58 |
1 files changed, 19 insertions, 39 deletions
diff --git a/src/pkg/crypto/hmac/hmac.go b/src/pkg/crypto/hmac/hmac.go index 04ec86e9a..a97ce0972 100644 --- a/src/pkg/crypto/hmac/hmac.go +++ b/src/pkg/crypto/hmac/hmac.go @@ -9,33 +9,20 @@ package hmac import ( - "crypto/md5" - "crypto/sha1" - "crypto/sha256" "hash" - "os" ) // FIPS 198: // http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf -// key is zero padded to 64 bytes -// ipad = 0x36 byte repeated to 64 bytes -// opad = 0x5c byte repeated to 64 bytes +// key is zero padded to the block size of the hash function +// ipad = 0x36 byte repeated for key length +// opad = 0x5c byte repeated for key length // hmac = H([key ^ opad] H([key ^ ipad] text)) -const ( - // NOTE(rsc): This constant is actually the - // underlying hash function's block size. - // HMAC is only conventionally used with - // MD5 and SHA1, and both use 64-byte blocks. - // The hash.Hash interface doesn't provide a - // way to find out the block size. - padSize = 64 -) - type hmac struct { size int + blocksize int key, tmp []byte outer, inner hash.Hash } @@ -44,57 +31,50 @@ func (h *hmac) tmpPad(xor byte) { for i, k := range h.key { h.tmp[i] = xor ^ k } - for i := len(h.key); i < padSize; i++ { + for i := len(h.key); i < h.blocksize; i++ { h.tmp[i] = xor } } -func (h *hmac) Sum() []byte { - sum := h.inner.Sum() +func (h *hmac) Sum(in []byte) []byte { + origLen := len(in) + in = h.inner.Sum(in) h.tmpPad(0x5c) - for i, b := range sum { - h.tmp[padSize+i] = b - } + copy(h.tmp[h.blocksize:], in[origLen:]) h.outer.Reset() h.outer.Write(h.tmp) - return h.outer.Sum() + return h.outer.Sum(in[:origLen]) } -func (h *hmac) Write(p []byte) (n int, err os.Error) { +func (h *hmac) Write(p []byte) (n int, err error) { return h.inner.Write(p) } func (h *hmac) Size() int { return h.size } +func (h *hmac) BlockSize() int { return h.blocksize } + func (h *hmac) Reset() { h.inner.Reset() h.tmpPad(0x36) - h.inner.Write(h.tmp[0:padSize]) + h.inner.Write(h.tmp[0:h.blocksize]) } -// New returns a new HMAC hash using the given hash generator and key. +// New returns a new HMAC hash using the given hash.Hash type and key. func New(h func() hash.Hash, key []byte) hash.Hash { hm := new(hmac) hm.outer = h() hm.inner = h() hm.size = hm.inner.Size() - hm.tmp = make([]byte, padSize+hm.size) - if len(key) > padSize { + hm.blocksize = hm.inner.BlockSize() + hm.tmp = make([]byte, hm.blocksize+hm.size) + if len(key) > hm.blocksize { // If key is too big, hash it. hm.outer.Write(key) - key = hm.outer.Sum() + key = hm.outer.Sum(nil) } hm.key = make([]byte, len(key)) copy(hm.key, key) hm.Reset() return hm } - -// NewMD5 returns a new HMAC-MD5 hash using the given key. -func NewMD5(key []byte) hash.Hash { return New(md5.New, key) } - -// NewSHA1 returns a new HMAC-SHA1 hash using the given key. -func NewSHA1(key []byte) hash.Hash { return New(sha1.New, key) } - -// NewSHA256 returns a new HMAC-SHA256 hash using the given key. -func NewSHA256(key []byte) hash.Hash { return New(sha256.New, key) } |