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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "crypto/ec_signature_creator_impl.h"
#include <openssl/bn.h>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include "base/logging.h"
#include "crypto/ec_private_key.h"
#include "crypto/openssl_util.h"
#include "crypto/scoped_openssl_types.h"
namespace crypto {
namespace {
typedef ScopedOpenSSL<ECDSA_SIG, ECDSA_SIG_free>::Type ScopedECDSA_SIG;
} // namespace
ECSignatureCreatorImpl::ECSignatureCreatorImpl(ECPrivateKey* key)
: key_(key), signature_len_(0) {
EnsureOpenSSLInit();
}
ECSignatureCreatorImpl::~ECSignatureCreatorImpl() {}
bool ECSignatureCreatorImpl::Sign(const uint8* data,
int data_len,
std::vector<uint8>* signature) {
OpenSSLErrStackTracer err_tracer(FROM_HERE);
ScopedEVP_MD_CTX ctx(EVP_MD_CTX_create());
size_t sig_len = 0;
if (!ctx.get() ||
!EVP_DigestSignInit(ctx.get(), NULL, EVP_sha256(), NULL, key_->key()) ||
!EVP_DigestSignUpdate(ctx.get(), data, data_len) ||
!EVP_DigestSignFinal(ctx.get(), NULL, &sig_len)) {
return false;
}
signature->resize(sig_len);
if (!EVP_DigestSignFinal(ctx.get(), &signature->front(), &sig_len))
return false;
// NOTE: A call to EVP_DigestSignFinal() with a NULL second parameter returns
// a maximum allocation size, while the call without a NULL returns the real
// one, which may be smaller.
signature->resize(sig_len);
return true;
}
bool ECSignatureCreatorImpl::DecodeSignature(const std::vector<uint8>& der_sig,
std::vector<uint8>* out_raw_sig) {
OpenSSLErrStackTracer err_tracer(FROM_HERE);
// Create ECDSA_SIG object from DER-encoded data.
const unsigned char* der_data = &der_sig.front();
ScopedECDSA_SIG ecdsa_sig(
d2i_ECDSA_SIG(NULL, &der_data, static_cast<long>(der_sig.size())));
if (!ecdsa_sig.get())
return false;
// The result is made of two 32-byte vectors.
const size_t kMaxBytesPerBN = 32;
std::vector<uint8> result;
result.resize(2 * kMaxBytesPerBN);
memset(&result[0], 0, result.size());
BIGNUM* r = ecdsa_sig.get()->r;
BIGNUM* s = ecdsa_sig.get()->s;
int r_bytes = BN_num_bytes(r);
int s_bytes = BN_num_bytes(s);
// NOTE: Can't really check for equality here since sometimes the value
// returned by BN_num_bytes() will be slightly smaller than kMaxBytesPerBN.
if (r_bytes > static_cast<int>(kMaxBytesPerBN) ||
s_bytes > static_cast<int>(kMaxBytesPerBN)) {
DLOG(ERROR) << "Invalid key sizes r(" << r_bytes << ") s(" << s_bytes
<< ")";
return false;
}
BN_bn2bin(ecdsa_sig.get()->r, &result[kMaxBytesPerBN - r_bytes]);
BN_bn2bin(ecdsa_sig.get()->s, &result[2 * kMaxBytesPerBN - s_bytes]);
out_raw_sig->swap(result);
return true;
}
} // namespace crypto
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