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