mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-30 19:53:46 +00:00
81 lines
1.9 KiB
Go
81 lines
1.9 KiB
Go
// Copyright 2009 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 hmac implements the Keyed-Hash Message Authentication Code (HMAC) as
|
|
// defined in U.S. Federal Information Processing Standards Publication 198.
|
|
// An HMAC is a cryptographic hash that uses a key to sign a message.
|
|
// The receiver verifies the hash by recomputing it using the same key.
|
|
package hmac
|
|
|
|
import (
|
|
"hash"
|
|
)
|
|
|
|
// FIPS 198:
|
|
// http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf
|
|
|
|
// 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))
|
|
|
|
type hmac struct {
|
|
size int
|
|
blocksize int
|
|
key, tmp []byte
|
|
outer, inner hash.Hash
|
|
}
|
|
|
|
func (h *hmac) tmpPad(xor byte) {
|
|
for i, k := range h.key {
|
|
h.tmp[i] = xor ^ k
|
|
}
|
|
for i := len(h.key); i < h.blocksize; i++ {
|
|
h.tmp[i] = xor
|
|
}
|
|
}
|
|
|
|
func (h *hmac) Sum(in []byte) []byte {
|
|
origLen := len(in)
|
|
in = h.inner.Sum(in)
|
|
h.tmpPad(0x5c)
|
|
copy(h.tmp[h.blocksize:], in[origLen:])
|
|
h.outer.Reset()
|
|
h.outer.Write(h.tmp)
|
|
return h.outer.Sum(in[:origLen])
|
|
}
|
|
|
|
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:h.blocksize])
|
|
}
|
|
|
|
// 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.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(nil)
|
|
}
|
|
hm.key = make([]byte, len(key))
|
|
copy(hm.key, key)
|
|
hm.Reset()
|
|
return hm
|
|
}
|