Implement the signature verification API.

base/crypto/signature_verifier_win.cc

+// Copyright (c) 2009 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 "base/crypto/signature_verifier.h"
+
+#include "base/logging.h"
+
+#pragma comment(lib, "crypt32.lib")
+
+namespace {
+
+// Wrappers of malloc and free for CRYPT_DECODE_PARA, which requires the
+// WINAPI calling convention.
+void* WINAPI MyCryptAlloc(size_t size) {
+  return malloc(size);
+}
+
+void WINAPI MyCryptFree(void* p) {
+  free(p);
+}
+
+}  // namespace
+
+namespace base {
+
+SignatureVerifier::SignatureVerifier() : hash_object_(0), public_key_(0) {
+  if (!CryptAcquireContext(&provider_, NULL, NULL,
+                           PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
+    provider_ = 0;
+}
+
+SignatureVerifier::~SignatureVerifier() {
+  Reset();
+  if (provider_) {
+    BOOL ok = CryptReleaseContext(provider_, 0);
+    DCHECK(ok);
+  }
+}
+
+bool SignatureVerifier::VerifyInit(const uint8* signature_algorithm,
+                                   int signature_algorithm_len,
+                                   const uint8* signature,
+                                   int signature_len,
+                                   const uint8* public_key_info,
+                                   int public_key_info_len) {
+  signature_.reserve(signature_len);
+  // CryptoAPI uses big integers in the little-endian byte order, so we need
+  // to first swap the order of signature bytes.
+  for (int i = signature_len - 1; i >= 0; --i)
+    signature_.push_back(signature[i]);
+
+  CRYPT_DECODE_PARA decode_para;
+  decode_para.cbSize = sizeof(decode_para);
+  decode_para.pfnAlloc = MyCryptAlloc;
+  decode_para.pfnFree = MyCryptFree;
+  CERT_PUBLIC_KEY_INFO* cert_public_key_info = NULL;
+  DWORD struct_len = 0;
+  BOOL ok;
+  ok = CryptDecodeObjectEx(X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
+                           X509_PUBLIC_KEY_INFO,
+                           public_key_info,
+                           public_key_info_len,
+                           CRYPT_DECODE_ALLOC_FLAG | CRYPT_DECODE_NOCOPY_FLAG,
+                           &decode_para,
+                           &cert_public_key_info,
+                           &struct_len);
+  if (!ok)
+    return false;
+
+  ok = CryptImportPublicKeyInfo(provider_,
+                                X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
+                                cert_public_key_info, &public_key_);
+  free(cert_public_key_info);
+  if (!ok)
+    return false;
+
+  CRYPT_ALGORITHM_IDENTIFIER* signature_algorithm_id;
+  struct_len = 0;
+  ok = CryptDecodeObjectEx(X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
+                           X509_ALGORITHM_IDENTIFIER,
+                           signature_algorithm,
+                           signature_algorithm_len,
+                           CRYPT_DECODE_ALLOC_FLAG | CRYPT_DECODE_NOCOPY_FLAG,
+                           &decode_para,
+                           &signature_algorithm_id,
+                           &struct_len);
+  DCHECK(ok || GetLastError() == ERROR_FILE_NOT_FOUND);
+  ALG_ID hash_alg_id;
+  if (ok) {
+    hash_alg_id = CALG_MD4;  // Initialize to a weak hash algorithm that we
+                             // don't support.
+    if (!strcmp(signature_algorithm_id->pszObjId, szOID_RSA_SHA1RSA))
+      hash_alg_id = CALG_SHA1;
+    else if (!strcmp(signature_algorithm_id->pszObjId, szOID_RSA_MD5RSA))
+      hash_alg_id = CALG_MD5;
+    free(signature_algorithm_id);
+    DCHECK(hash_alg_id != CALG_MD4);
+    if (hash_alg_id == CALG_MD4)
+      return false;  // Unsupported hash algorithm.
+  } else if (GetLastError() == ERROR_FILE_NOT_FOUND) {
+    // TODO(wtc): X509_ALGORITHM_IDENTIFIER isn't supported on XP SP2.  We
+    // may be able to encapsulate signature_algorithm in a dummy SignedContent
+    // and decode it with X509_CERT into a CERT_SIGNED_CONTENT_INFO.  For now,
+    // just hardcode the hash algorithm to be SHA-1.
+    hash_alg_id = CALG_SHA1;
+  } else {
+    return false;
+  }
+
+  ok = CryptCreateHash(provider_, hash_alg_id, 0, 0, &hash_object_);
+  if (!ok)
+    return false;
+  return true;
+}
+
+void SignatureVerifier::VerifyUpdate(const uint8* data_part,
+                                     int data_part_len) {
+  BOOL ok = CryptHashData(hash_object_, data_part, data_part_len, 0);
+  DCHECK(ok) << "CryptHashData failed: " << GetLastError();
+}
+
+bool SignatureVerifier::VerifyFinal() {
+  BOOL ok = CryptVerifySignature(hash_object_, &signature_[0],
+                                 signature_.size(), public_key_, NULL, 0);
+  Reset();
+  if (!ok)
+    return false;
+  return true;
+}
+
+void SignatureVerifier::Reset() {
+  BOOL ok;
+  if (hash_object_) {
+    ok = CryptDestroyHash(hash_object_);
+    DCHECK(ok);
+    hash_object_ = 0;
+  }
+  if (public_key_) {
+    ok =  CryptDestroyKey(public_key_);
+    DCHECK(ok);
+    public_key_ = 0;
+  }
+  signature_.clear();
+}
+
+}  // namespace base
+