Current File : //data/old/usr/lib/golang/src/crypto/internal/boring/hmac.go
// Copyright 2017 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.
//go:build linux && !android && !cmd_go_bootstrap && !msan && !no_openssl && !static
// +build linux,!android,!cmd_go_bootstrap,!msan,!no_openssl,!static
package boring
// #include "goboringcrypto.h"
import "C"
import (
"crypto"
"hash"
"runtime"
"unsafe"
)
// hashToMD converts a hash.Hash implementation from this package
// to a BoringCrypto *C.GO_EVP_MD.
func hashToMD(h hash.Hash) *C.GO_EVP_MD {
switch h.(type) {
case *sha1Hash:
return C._goboringcrypto_EVP_sha1()
case *sha224Hash:
return C._goboringcrypto_EVP_sha224()
case *sha256Hash:
return C._goboringcrypto_EVP_sha256()
case *sha384Hash:
return C._goboringcrypto_EVP_sha384()
case *sha512Hash:
return C._goboringcrypto_EVP_sha512()
}
return nil
}
// cryptoHashToMD converts a crypto.Hash
// to a BoringCrypto *C.GO_EVP_MD.
func cryptoHashToMD(ch crypto.Hash) *C.GO_EVP_MD {
switch ch {
case crypto.MD5:
return C._goboringcrypto_EVP_md5()
case crypto.MD5SHA1:
return C._goboringcrypto_EVP_md5_sha1()
case crypto.SHA1:
return C._goboringcrypto_EVP_sha1()
case crypto.SHA224:
return C._goboringcrypto_EVP_sha224()
case crypto.SHA256:
return C._goboringcrypto_EVP_sha256()
case crypto.SHA384:
return C._goboringcrypto_EVP_sha384()
case crypto.SHA512:
return C._goboringcrypto_EVP_sha512()
}
return nil
}
// NewHMAC returns a new HMAC using BoringCrypto.
// The function h must return a hash implemented by
// BoringCrypto (for example, h could be boring.NewSHA256).
// If h is not recognized, NewHMAC returns nil.
func NewHMAC(h func() hash.Hash, key []byte) hash.Hash {
ch := h()
md := hashToMD(ch)
if md == nil {
return nil
}
var hkey []byte
if key != nil && len(key) > 0 {
// Note: Could hash down long keys here using EVP_Digest.
hkey = make([]byte, len(key))
copy(hkey, key)
} else {
// This is supported in BoringSSL/Standard lib and as such
// we must support it here. When using HMAC with a null key
// HMAC_Init will try and reuse the key from the ctx. This is
// not the bahavior previously implemented, so as a workaround
// we pass an "empty" key.
hkey = make([]byte, C.EVP_MAX_MD_SIZE)
}
hmac := &boringHMAC{
md: md,
size: ch.Size(),
blockSize: ch.BlockSize(),
key: hkey,
ctx: C._goboringcrypto_HMAC_CTX_new(),
}
hmac.Reset()
return hmac
}
type boringHMAC struct {
md *C.GO_EVP_MD
ctx *C.GO_HMAC_CTX
ctx2 *C.GO_HMAC_CTX
size int
blockSize int
key []byte
sum []byte
needCleanup bool
}
func (h *boringHMAC) Reset() {
if !h.needCleanup {
h.needCleanup = true
// Note: Because of the finalizer, any time h.ctx is passed to cgo,
// that call must be followed by a call to runtime.KeepAlive(h),
// to make sure h is not collected (and finalized) before the cgo
// call returns.
runtime.SetFinalizer(h, (*boringHMAC).finalize)
}
C._goboringcrypto_HMAC_CTX_reset(h.ctx)
if C._goboringcrypto_HMAC_Init_ex(h.ctx, unsafe.Pointer(base(h.key)), C.int(len(h.key)), h.md, nil) == 0 {
panic("boringcrypto: HMAC_Init failed")
}
if int(C._goboringcrypto_HMAC_size(h.ctx)) != h.size {
println("boringcrypto: HMAC size:", C._goboringcrypto_HMAC_size(h.ctx), "!=", h.size)
panic("boringcrypto: HMAC size mismatch")
}
runtime.KeepAlive(h) // Next line will keep h alive too; just making doubly sure.
h.sum = nil
}
func (h *boringHMAC) finalize() {
C._goboringcrypto_HMAC_CTX_free(h.ctx)
}
func (h *boringHMAC) Write(p []byte) (int, error) {
if len(p) > 0 {
C._goboringcrypto_HMAC_Update(h.ctx, (*C.uint8_t)(unsafe.Pointer(&p[0])), C.size_t(len(p)))
}
runtime.KeepAlive(h)
return len(p), nil
}
func (h *boringHMAC) Size() int {
return h.size
}
func (h *boringHMAC) BlockSize() int {
return h.blockSize
}
func (h *boringHMAC) Sum(in []byte) []byte {
if h.sum == nil {
size := h.Size()
h.sum = make([]byte, size)
}
// Make copy of context because Go hash.Hash mandates
// that Sum has no effect on the underlying stream.
// In particular it is OK to Sum, then Write more, then Sum again,
// and the second Sum acts as if the first didn't happen.
h.ctx2 = C._goboringcrypto_HMAC_CTX_new()
if C._goboringcrypto_HMAC_CTX_copy_ex(h.ctx2, h.ctx) == 0 {
panic("boringcrypto: HMAC_CTX_copy_ex failed")
}
C._goboringcrypto_HMAC_Final(h.ctx2, (*C.uint8_t)(unsafe.Pointer(&h.sum[0])), nil)
C._goboringcrypto_HMAC_CTX_free(h.ctx2)
return append(in, h.sum...)
}
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