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
  17 namespace crypto {
  18
  19 ECSignatureCreatorImpl::ECSignatureCreatorImpl(ECPrivateKey* key)
  20     : key_(key), signature_len_(0) {
  21   EnsureOpenSSLInit();
  22 }
  23
  24 ECSignatureCreatorImpl::~ECSignatureCreatorImpl() {}
  25
  26 bool ECSignatureCreatorImpl::Sign(const uint8* data,
  27                                   int data_len,
  28                                   std::vector<uint8>* signature) {
  29   OpenSSLErrStackTracer err_tracer(FROM_HERE);
  30   ScopedOpenSSL<EVP_MD_CTX, EVP_MD_CTX_destroy> ctx(EVP_MD_CTX_create());
  31   size_t sig_len = 0;
  32   if (!ctx.get() ||
  33       !EVP_DigestSignInit(ctx.get(), NULL, EVP_sha256(), NULL, key_->key()) ||
  34       !EVP_DigestSignUpdate(ctx.get(), data, data_len) ||
  35       !EVP_DigestSignFinal(ctx.get(), NULL, &sig_len)) {
  36     return false;
  37   }
  38
  39   signature->resize(sig_len);
  40   if (!EVP_DigestSignFinal(ctx.get(), &signature->front(), &sig_len))
  41     return false;
  42
  43   // NOTE: A call to EVP_DigestSignFinal() with a NULL second parameter returns
  44   // a maximum allocation size, while the call without a NULL returns the real
  45   // one, which may be smaller.
  46   signature->resize(sig_len);
  47   return true;
  48 }
  49
  50 bool ECSignatureCreatorImpl::DecodeSignature(const std::vector<uint8>& der_sig,
  51                                              std::vector<uint8>* out_raw_sig) {
  52   OpenSSLErrStackTracer err_tracer(FROM_HERE);
  53   // Create ECDSA_SIG object from DER-encoded data.
  54   const unsigned char* der_data = &der_sig.front();
  55   ScopedOpenSSL<ECDSA_SIG, ECDSA_SIG_free> ecdsa_sig(
  56       d2i_ECDSA_SIG(NULL, &der_data, static_cast<long>(der_sig.size())));
  57   if (!ecdsa_sig.get())
  58     return false;
  59
  60   // The result is made of two 32-byte vectors.
  61   const size_t kMaxBytesPerBN = 32;
  62   std::vector<uint8> result;
  63   result.resize(2 * kMaxBytesPerBN);
  64   memset(&result[0], 0, result.size());
  65
  66   BIGNUM* r = ecdsa_sig.get()->r;
  67   BIGNUM* s = ecdsa_sig.get()->s;
  68   int r_bytes = BN_num_bytes(r);
  69   int s_bytes = BN_num_bytes(s);
  70   // NOTE: Can't really check for equality here since sometimes the value
  71   // returned by BN_num_bytes() will be slightly smaller than kMaxBytesPerBN.
  72   if (r_bytes > static_cast<int>(kMaxBytesPerBN) ||
  73       s_bytes > static_cast<int>(kMaxBytesPerBN)) {
  74     DLOG(ERROR) << "Invalid key sizes r(" << r_bytes << ") s(" << s_bytes
  75                 << ")";
  76     return false;
  77   }
  78   BN_bn2bin(ecdsa_sig.get()->r, &result[kMaxBytesPerBN - r_bytes]);
  79   BN_bn2bin(ecdsa_sig.get()->s, &result[2 * kMaxBytesPerBN - s_bytes]);
  80   out_raw_sig->swap(result);
  81   return true;
  82 }
  83
  84 }  // namespace crypto