text: // Copyright 2013 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 "net/quic/crypto/channel_id.h"
  
  #include <openssl/bn.h>
  #include <openssl/ec.h>
  #include <openssl/ecdsa.h>
  #include <openssl/obj_mac.h>
  #include <openssl/sha.h>
  
  #include "crypto/openssl_util.h"
  
  using base::StringPiece;
  
  namespace net {
  
  // static
  bool ChannelIDVerifier::Verify(StringPiece key,
                                 StringPiece signed_data,
                                 StringPiece signature) {
    return VerifyRaw(key, signed_data, signature, true);
  }
  
  // static
  bool ChannelIDVerifier::VerifyRaw(StringPiece key,
                                    StringPiece signed_data,
                                    StringPiece signature,
                                    bool is_channel_id_signature) {
    if (key.size() != 32 * 2 ||
        signature.size() != 32 * 2) {
      return false;
    }
  
    crypto::ScopedOpenSSL<EC_GROUP, EC_GROUP_free> p256(
        EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1));
    if (p256.get() == NULL) {
      return false;
    }
  
    crypto::ScopedOpenSSL<BIGNUM, BN_free> x(BN_new()), y(BN_new()),
                                           r(BN_new()), s(BN_new());
  
    ECDSA_SIG sig;
    sig.r = r.get();
    sig.s = s.get();
  
    const uint8* key_bytes = reinterpret_cast<const uint8*>(key.data());
    const uint8* proof_bytes = reinterpret_cast<const uint8*>(signature.data());
  
    if (BN_bin2bn(key_bytes   +  0, 32, x.get()) == NULL ||
        BN_bin2bn(key_bytes   + 32, 32, y.get()) == NULL ||
        BN_bin2bn(proof_bytes +  0, 32, sig.r) == NULL ||
        BN_bin2bn(proof_bytes + 32, 32, sig.s) == NULL) {
      return false;
    }
  
    crypto::ScopedOpenSSL<EC_POINT, EC_POINT_free> point(
        EC_POINT_new(p256.get()));
    if (point.get() == NULL ||
        !EC_POINT_set_affine_coordinates_GFp(p256.get(), point.get(), x.get(),
                                             y.get(), NULL)) {
      return false;
    }
  
    crypto::ScopedOpenSSL<EC_KEY, EC_KEY_free> ecdsa_key(EC_KEY_new());
    if (ecdsa_key.get() == NULL ||
        !EC_KEY_set_group(ecdsa_key.get(), p256.get()) ||
        !EC_KEY_set_public_key(ecdsa_key.get(), point.get())) {
      return false;
    }
  
    SHA256_CTX sha256;
    SHA256_Init(&sha256);
    if (is_channel_id_signature) {
      SHA256_Update(&sha256, kContextStr, strlen(kContextStr) + 1);
      SHA256_Update(&sha256, kClientToServerStr, strlen(kClientToServerStr) + 1);
    }
    SHA256_Update(&sha256, signed_data.data(), signed_data.size());
  
    unsigned char digest[SHA256_DIGEST_LENGTH];
    SHA256_Final(digest, &sha256);
  
    return ECDSA_do_verify(digest, sizeof(digest), &sig, ecdsa_key.get()) == 1;
  }
  
  }  // namespace net
  