crypto/ec_signature_creator_openssl.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "crypto/ec_signature_creator_impl.h"
   6
   7 #include <openssl/bn.h>
   8 #include <openssl/ec.h>
   9 #include <openssl/ecdsa.h>
  10 #include <openssl/evp.h>
  11 #include <openssl/sha.h>
  12
  13 #include "base/logging.h"
  14 #include "crypto/ec_private_key.h"
  15 #include "crypto/openssl_util.h"
  16 #include "crypto/scoped_openssl_types.h"
  17
  18 namespace crypto {
  19
  20 namespace {
  21
  22 typedef ScopedOpenSSL<ECDSA_SIG, ECDSA_SIG_free>::Type ScopedECDSA_SIG;
  23
  24 }  // namespace
  25
  26 ECSignatureCreatorImpl::ECSignatureCreatorImpl(ECPrivateKey* key)
  27     : key_(key), signature_len_(0) {
  28   EnsureOpenSSLInit();
  29 }
  30
  31 ECSignatureCreatorImpl::~ECSignatureCreatorImpl() {}
  32
  33 bool ECSignatureCreatorImpl::Sign(const uint8* data,
  34                                   int data_len,
  35                                   std::vector<uint8>* signature) {
  36   OpenSSLErrStackTracer err_tracer(FROM_HERE);
  37   ScopedEVP_MD_CTX ctx(EVP_MD_CTX_create());
  38   size_t sig_len = 0;
  39   if (!ctx.get() ||
  40       !EVP_DigestSignInit(ctx.get(), NULL, EVP_sha256(), NULL, key_->key()) ||
  41       !EVP_DigestSignUpdate(ctx.get(), data, data_len) ||
  42       !EVP_DigestSignFinal(ctx.get(), NULL, &sig_len)) {
  43     return false;
  44   }
  45
  46   signature->resize(sig_len);
  47   if (!EVP_DigestSignFinal(ctx.get(), &signature->front(), &sig_len))
  48     return false;
  49
  50   // NOTE: A call to EVP_DigestSignFinal() with a NULL second parameter returns
  51   // a maximum allocation size, while the call without a NULL returns the real
  52   // one, which may be smaller.
  53   signature->resize(sig_len);
  54   return true;
  55 }
  56
  57 bool ECSignatureCreatorImpl::DecodeSignature(const std::vector<uint8>& der_sig,
  58                                              std::vector<uint8>* out_raw_sig) {
  59   OpenSSLErrStackTracer err_tracer(FROM_HERE);
  60   // Create ECDSA_SIG object from DER-encoded data.
  61   const unsigned char* der_data = &der_sig.front();
  62   ScopedECDSA_SIG ecdsa_sig(
  63       d2i_ECDSA_SIG(NULL, &der_data, static_cast<long>(der_sig.size())));
  64   if (!ecdsa_sig.get())
  65     return false;
  66
  67   // The result is made of two 32-byte vectors.
  68   const size_t kMaxBytesPerBN = 32;
  69   std::vector<uint8> result;
  70   result.resize(2 * kMaxBytesPerBN);
  71   memset(&result[0], 0, result.size());
  72
  73   BIGNUM* r = ecdsa_sig.get()->r;
  74   BIGNUM* s = ecdsa_sig.get()->s;
  75   int r_bytes = BN_num_bytes(r);
  76   int s_bytes = BN_num_bytes(s);
  77   // NOTE: Can't really check for equality here since sometimes the value
  78   // returned by BN_num_bytes() will be slightly smaller than kMaxBytesPerBN.
  79   if (r_bytes > static_cast<int>(kMaxBytesPerBN) ||
  80       s_bytes > static_cast<int>(kMaxBytesPerBN)) {
  81     DLOG(ERROR) << "Invalid key sizes r(" << r_bytes << ") s(" << s_bytes
  82                 << ")";
  83     return false;
  84   }
  85   BN_bn2bin(ecdsa_sig.get()->r, &result[kMaxBytesPerBN - r_bytes]);
  86   BN_bn2bin(ecdsa_sig.get()->s, &result[2 * kMaxBytesPerBN - s_bytes]);
  87   out_raw_sig->swap(result);
  88   return true;
  89 }
  90
  91 }  // namespace crypto