Keep only base/extractor.[cc|h].

base/security/challenger.cc

-// Copyright 2007-2009 Google Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-// ========================================================================
-
-#include "challenger.h"
-
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-
-#include "rsa.h"
-#include "md5.h"
-#include "aes.h"
-#include "b64.h"
-
-// Windows compilers do not have C99 support yet.
-#if defined(WIN32) || defined(_WIN32)
-#ifndef snprintf
-#define snprintf _snprintf
-#endif
-#endif
-
-Challenger::Challenger(RSA::PublicKey pkey,
-                       const unsigned char* seed, int seed_size)
-    : rsa_(pkey) {
-  memset(count_, 0, sizeof(count_));
-  // Use seed as key for AES. Compress seed first.
-  MD5(seed, seed_size, seed_);
-}
-
-const char* Challenger::challenge() {
-  uint8_t ctr[AES_BLOCK_SIZE];
-
-  // Compute current challenge.
-  AES_encrypt_block(seed_, count_, ctr);
-
-  // Increment count for future fresh challenges.
-  for (size_t i = 0; i < sizeof(count_) && !++count_[i]; ++i);
-
-  // Prepend our version number.
-  char* p = challenge_;
-  p += snprintf(challenge_, sizeof(challenge_), "%d:", rsa_.version());
-
-  // Append our current challenge.
-  B64_encode(ctr, sizeof(ctr), p, sizeof(challenge_) - (p - challenge_));
-
-  return challenge_;
-}
-
-bool Challenger::verify(const char* hash, const char* signature) const {
-  char message[128];
-  uint8_t sigbuf[128];
-
-  // Expect exactly 128 bytes of decoded signature data.
-  if (B64_decode(signature, sigbuf, sizeof(sigbuf)) != sizeof(sigbuf))
-    return false;
-
-  // Verify signature with baked-in public key and recover embedded message.
-  int result = rsa_.verify(sigbuf, sizeof(sigbuf),
-                           message, sizeof(message) - 1);
-
-  if (result < 0 || result >= static_cast<int>(sizeof(message) - 1))
-    return false;
-
-  // Since we're expecting a textual message, 0-terminate it.
-  message[result] = '\0';
-
-  // Construct and compare expected against received signed message.
-  char expected[128];
-  snprintf(expected, sizeof(expected), "%s:%s", challenge_, hash);
-
-  return !strcmp(expected, message);
-}