92 lines
2.2 KiB
Go
92 lines
2.2 KiB
Go
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// Copyright (C) 2017. See AUTHORS.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package openssl
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// #include "shim.h"
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import "C"
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import (
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"errors"
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"runtime"
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"unsafe"
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)
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type HMAC struct {
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ctx *C.HMAC_CTX
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engine *Engine
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md *C.EVP_MD
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}
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func NewHMAC(key []byte, digestAlgorithm EVP_MD) (*HMAC, error) {
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return NewHMACWithEngine(key, digestAlgorithm, nil)
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}
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func NewHMACWithEngine(key []byte, digestAlgorithm EVP_MD, e *Engine) (*HMAC, error) {
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var md *C.EVP_MD = getDigestFunction(digestAlgorithm)
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h := &HMAC{engine: e, md: md}
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h.ctx = C.X_HMAC_CTX_new()
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if h.ctx == nil {
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return nil, errors.New("unable to allocate HMAC_CTX")
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}
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var c_e *C.ENGINE
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if e != nil {
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c_e = e.e
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}
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if rc := C.X_HMAC_Init_ex(h.ctx,
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unsafe.Pointer(&key[0]),
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C.int(len(key)),
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md,
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c_e); rc != 1 {
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C.X_HMAC_CTX_free(h.ctx)
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return nil, errors.New("failed to initialize HMAC_CTX")
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}
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runtime.SetFinalizer(h, func(h *HMAC) { h.Close() })
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return h, nil
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}
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func (h *HMAC) Close() {
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C.X_HMAC_CTX_free(h.ctx)
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}
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func (h *HMAC) Write(data []byte) (n int, err error) {
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if len(data) == 0 {
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return 0, nil
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}
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if rc := C.X_HMAC_Update(h.ctx, (*C.uchar)(unsafe.Pointer(&data[0])),
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C.size_t(len(data))); rc != 1 {
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return 0, errors.New("failed to update HMAC")
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}
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return len(data), nil
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}
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func (h *HMAC) Reset() error {
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if 1 != C.X_HMAC_Init_ex(h.ctx, nil, 0, nil, nil) {
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return errors.New("failed to reset HMAC_CTX")
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}
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return nil
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}
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func (h *HMAC) Final() (result []byte, err error) {
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mdLength := C.X_EVP_MD_size(h.md)
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result = make([]byte, mdLength)
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if rc := C.X_HMAC_Final(h.ctx, (*C.uchar)(unsafe.Pointer(&result[0])),
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(*C.uint)(unsafe.Pointer(&mdLength))); rc != 1 {
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return nil, errors.New("failed to finalized HMAC")
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}
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return result, h.Reset()
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}
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