Adds support for the <keygen> element to Windows, matching support present on...

net/base/keygen_handler_win.cc

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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/base/keygen_handler.h"
 
+#include <windows.h>
+#include <wincrypt.h>
+#pragma comment(lib, "crypt32.lib")
+#include <rpc.h>
+#pragma comment(lib, "rpcrt4.lib")
+
+#include <list>
+#include <string>
+#include <vector>
+
+#include "base/base64.h"
+#include "base/basictypes.h"
 #include "base/logging.h"
+#include "base/string_piece.h"
+#include "base/utf_string_conversions.h"
 
 namespace net {
 
+// TODO(rsleevi): The following encoding functions are adapted from
+// base/crypto/rsa_private_key.h and can/should probably be refactored
+static const uint8 kSequenceTag = 0x30;
+
+void PrependLength(size_t size, std::list<BYTE>* data) {
+  // The high bit is used to indicate whether additional octets are needed to
+  // represent the length.
+  if (size < 0x80) {
+    data->push_front(static_cast<BYTE>(size));
+  } else {
+    uint8 num_bytes = 0;
+    while (size > 0) {
+      data->push_front(static_cast<BYTE>(size & 0xFF));
+      size >>= 8;
+      num_bytes++;
+    }
+    CHECK_LE(num_bytes, 4);
+    data->push_front(0x80 | num_bytes);
+  }
+}
+
+void PrependTypeHeaderAndLength(uint8 type, uint32 length,
+                                std::vector<BYTE>* output) {
+  std::list<BYTE> type_and_length;
+
+  PrependLength(length, &type_and_length);
+  type_and_length.push_front(type);
+
+  output->insert(output->begin(), type_and_length.begin(),
+                 type_and_length.end());
+}
+
+bool EncodeAndAppendType(LPCSTR type, const void* to_encode,
+                         std::vector<BYTE>* output) {
+  BOOL ok;
+  DWORD size = 0;
+  ok = CryptEncodeObject(X509_ASN_ENCODING, type, to_encode, NULL, &size);
+  DCHECK(ok);
+  if (!ok)
+    return false;
+
+  std::vector<BYTE>::size_type old_size = output->size();
+  output->resize(old_size + size);
+
+  ok = CryptEncodeObject(X509_ASN_ENCODING, type, to_encode,
+                         &(*output)[old_size], &size);
+  DCHECK(ok);
+  if (!ok)
+    return false;
+
+  // Sometimes the initial call to CryptEncodeObject gave a generous estimate of
+  // the size, so shrink back to what was actually used
+  output->resize(old_size + size);
+
+  return true;
+}
+
+// Appends a DER IA5String containing |challenge| to |output|
+// Returns true if encoding was successful
+bool EncodeChallenge(const std::string& challenge, std::vector<BYTE>* output) {
+  CERT_NAME_VALUE challenge_nv;
+  challenge_nv.dwValueType = CERT_RDN_IA5_STRING;
+  challenge_nv.Value.pbData = const_cast<BYTE*>(
+      reinterpret_cast<const BYTE*>(challenge.c_str()));
+  challenge_nv.Value.cbData = challenge.size();
+
+  return EncodeAndAppendType(X509_ANY_STRING, &challenge_nv, output);
+}
+
+// Appends a DER SubjectPublicKeyInfo structure for the signing key in |prov|
+// to |output|
+// Returns true if encoding was successful
+bool EncodeSubjectPublicKeyInfo(HCRYPTPROV prov, std::vector<BYTE>* output) {
+  BOOL ok;
+  DWORD size = 0;
+
+  // From the private key stored in HCRYPTPROV, obtain the public key, stored as
+  // a CERT_PUBLIC_KEY_INFO structure. Currently, only RSA public keys are
+  // supported
+  ok = CryptExportPublicKeyInfoEx(prov, AT_KEYEXCHANGE, X509_ASN_ENCODING,
+                                  szOID_RSA_RSA, 0, NULL, NULL, &size);
+  DCHECK(ok);
+  if (!ok)
+    return false;
+
+  std::vector<BYTE> public_key_info(size);
+  PCERT_PUBLIC_KEY_INFO public_key_casted =
+      reinterpret_cast<PCERT_PUBLIC_KEY_INFO>(&public_key_info[0]);
+  ok = CryptExportPublicKeyInfoEx(prov, AT_KEYEXCHANGE, X509_ASN_ENCODING,
+                                  szOID_RSA_RSA, 0, NULL, public_key_casted,
+                                  &size);
+  DCHECK(ok);
+  if (!ok)
+    return false;
+
+  public_key_info.resize(size);
+
+  return EncodeAndAppendType(X509_PUBLIC_KEY_INFO, &public_key_info[0],
+                             output);
+}
+
+// Generates an ASN.1 DER representation of the PublicKeyAndChallenge structure
+// from the signing key of |prov| and the specified |challenge| and appends it
+// to |output|
+// True if the the encoding was successfully generated
+bool GetPublicKeyAndChallenge(HCRYPTPROV prov, const std::string& challenge,
+                              std::vector<BYTE>* output) {
+  if (!EncodeSubjectPublicKeyInfo(prov, output) ||
+      !EncodeChallenge(challenge, output)) {
+    return false;
+  }
+
+  PrependTypeHeaderAndLength(kSequenceTag, output->size(), output);
+  return true;
+}
+
+// Generates a DER encoded SignedPublicKeyAndChallenge structure from the
+// signing key of |prov| and the specified |challenge| string and appends it
+// to |output|
+// True if the encoding was successfully generated
+bool GetSignedPublicKeyAndChallenge(HCRYPTPROV prov,
+                                    const std::string& challenge,
+                                    std::string* output) {
+  std::vector<BYTE> pkac;
+  if (!GetPublicKeyAndChallenge(prov, challenge, &pkac))
+    return false;
+
+  std::vector<BYTE> signature;
+  std::vector<BYTE> signed_pkac;
+  DWORD size = 0;
+  BOOL ok;
+
+  // While the MSDN documentation states that CERT_SIGNED_CONTENT_INFO should be
+  // an X.509 certificate type, for encoding this is not necessary. The result
+  // of encoding this structure will be a DER-encoded structure with the ASN.1
+  // equivalent of
+  //  ::= SEQUENCE {
+  //    ToBeSigned IMPLICIT OCTET STRING,
+  //    SignatureAlgorithm AlgorithmIdentifier,
+  //    Signature BIT STRING
+  //  }
+  //
+  // This happens to be the same naive type as an SPKAC, so this works.
+  CERT_SIGNED_CONTENT_INFO info;
+  info.ToBeSigned.cbData = pkac.size();
+  info.ToBeSigned.pbData = &pkac[0];
+  info.SignatureAlgorithm.pszObjId = szOID_RSA_MD5RSA;
+  info.SignatureAlgorithm.Parameters.cbData = 0;
+  info.SignatureAlgorithm.Parameters.pbData = NULL;
+
+  ok = CryptSignCertificate(prov, AT_KEYEXCHANGE, X509_ASN_ENCODING,
+                            info.ToBeSigned.pbData, info.ToBeSigned.cbData,
+                            &info.SignatureAlgorithm, NULL, NULL, &size);
+  DCHECK(ok);
+  if (!ok)
+    return false;
+
+  signature.resize(size);
+  info.Signature.cbData = signature.size();
+  info.Signature.pbData = &signature.front();
+  info.Signature.cUnusedBits = 0;
+
+  ok = CryptSignCertificate(prov, AT_KEYEXCHANGE, X509_ASN_ENCODING,
+                            info.ToBeSigned.pbData, info.ToBeSigned.cbData,
+                            &info.SignatureAlgorithm, NULL,
+                            info.Signature.pbData, &info.Signature.cbData);
+  DCHECK(ok);
+  if (!ok || !EncodeAndAppendType(X509_CERT, &info, &signed_pkac))
+    return false;
+
+  output->assign(reinterpret_cast<char*>(&signed_pkac.front()),
+                 signed_pkac.size());
+
+  return true;
+}
+
+// Generates a unique name for the container which will store the key that is
+// generated. The traditional Windows approach is to use a GUID here
+std::wstring GetNewKeyContainerId() {
+  RPC_STATUS status = RPC_S_OK;
+  std::wstring result;
+
+  UUID id = { 0 };
+  status = UuidCreateSequential(&id);
+  if (status != RPC_S_OK && status != RPC_S_UUID_LOCAL_ONLY)
+    return result;
+
+  RPC_WSTR rpc_string = NULL;
+  status = UuidToString(&id, &rpc_string);
+  if (status != RPC_S_OK)
+    return result;
+
+  // TODO(rsleevi): Is there a less-hackish way to get this through to convert
+  // the unsigned short to wchar_t?
+  result.assign(reinterpret_cast<wchar_t*>(rpc_string));
+  RpcStringFree(&rpc_string);
+
+  return result;
+}
+
+void StoreKeyLocationInCache(HCRYPTPROV prov) {
+  BOOL ok;
+  DWORD size = 0;
+
+  // Though it is known the container and provider name, as they are supplied
+  // during GenKeyAndSignChallenge, explicitly resolving them via
+  // CryptGetProvParam ensures that any defaults (such as provider name being
+  // NULL) or any CSP modifications to the container name are properly reflected
+
+  // Find the container name. Though the MSDN documentation states it will
+  // return the exact same value as supplied whent he provider was aquired, it
+  // also notes the return type will be CHAR, /not/ WCHAR
+  ok = CryptGetProvParam(prov, PP_CONTAINER, NULL, &size, 0);
+  if (!ok)
+    return;
+
+  std::vector<BYTE> buffer(size);
+  ok = CryptGetProvParam(prov, PP_CONTAINER, &buffer.front(), &size, 0);
+  if (!ok)
+    return;
+
+  KeygenHandler::KeyLocation key_location;
+  UTF8ToWide(reinterpret_cast<char*>(&buffer.front()), size,
+             &key_location.container_name);
+
+  // Get the provider name. This will always resolve, even if NULL (indicating
+  // the default provider) was supplied to the CryptAcquireContext
+  size = 0;
+  ok = CryptGetProvParam(prov, PP_NAME, NULL, &size, 0);
+  if (!ok)
+    return;
+
+  buffer.resize(size);
+  ok = CryptGetProvParam(prov, PP_NAME, &buffer.front(), &size, 0);
+  if (!ok)
+    return;
+
+  UTF8ToWide(reinterpret_cast<char*>(&buffer.front()), size,
+             &key_location.provider_name);
+
+  std::vector<BYTE> public_key_info;
+  if (!EncodeSubjectPublicKeyInfo(prov, &public_key_info))
+    return;
+
+  KeygenHandler::Cache* cache = KeygenHandler::Cache::GetInstance();
+  cache->Insert(std::string(public_key_info.begin(), public_key_info.end()),
+                key_location);
+}
+
+bool KeygenHandler::KeyLocation::Equals(
+    const KeygenHandler::KeyLocation& location) const {
+  return container_name == location.container_name &&
+         provider_name == location.provider_name;
+}
+
 std::string KeygenHandler::GenKeyAndSignChallenge() {
-  NOTIMPLEMENTED();
-  return std::string();
+  std::string result;
+
+  bool is_success = true;
+  HCRYPTPROV prov = NULL;
+  HCRYPTKEY key = NULL;
+  DWORD flags = (key_size_in_bits_ << 16) | CRYPT_EXPORTABLE;
+  std::string spkac;
+
+  std::wstring new_key_id;
+
+  // TODO(rsleevi): Have the user choose which provider they should use,
+  // which needs to be filtered by those providers which can provide the keytype
+  // requested of the keysize requested. This is especially important for
+  // generating certificates that will be stored on smart-cards.
+  const int kMaxAttempts = 5;
+  BOOL ok = FALSE;
+  for (int attempt = 0; attempt < kMaxAttempts; ++attempt) {
+    // Per MSDN documentation for CryptAcquireContext, if applications will be
+    // creating their own keys, they should ensure unique naming schemes to
+    // prevent overlap with any other applications or consumers of CSPs, and
+    // /should not/ store new keys within the default, NULL key container.
+    new_key_id = GetNewKeyContainerId();
+    if (new_key_id.empty())
+      return result;
+
+    // Only create new key containers, so that existing key containers are not
+    // overwritten
+    ok = CryptAcquireContext(&prov, new_key_id.c_str(), NULL, PROV_RSA_FULL,
+                             CRYPT_SILENT | CRYPT_NEWKEYSET);
+
+    if (ok != 0 || GetLastError() != NTE_BAD_KEYSET)
+      break;
+  }
+  if (!ok) {
+    LOG(ERROR) << "Couldn't acquire a CryptoAPI Provider Context: "
+               << GetLastError();
+    is_success = false;
+    goto failure;
+  }
+
+  if (!CryptGenKey(prov, CALG_RSA_KEYX, flags, &key)) {
+    LOG(ERROR) << "Couldn't generate an RSA key";
+    is_success = false;
+    goto failure;
+  }
+
+  if (!GetSignedPublicKeyAndChallenge(prov, challenge_, &spkac)) {
+    LOG(ERROR) << "Couldn't generate the signed public key and challenge";
+    is_success = false;
+    goto failure;
+  }
+
+  if (!base::Base64Encode(spkac, &result)) {
+    LOG(ERROR) << "Couldn't convert signed key into base64";
+    is_success = false;
+    goto failure;
+  }
+
+ failure:
+  if (!is_success) {
+    LOG(ERROR) << "SSL Keygen failed";
+  } else {
+    LOG(INFO) << "SSL Key succeeded";
+    StoreKeyLocationInCache(prov);
+  }
+  if (key) {
+    // Securely destroys the handle, but leaves the underlying key alone. The
+    // key can be obtained again by resolving the key location. If |stores_key_|
+    // is false, the underlying key will be destroyed below.
+    CryptDestroyKey(key);
+  }
+
+  if (prov) {
+    CryptReleaseContext(prov, 0);
+    prov = NULL;
+    if (!stores_key_) {
+      // Fully destroys any of the keys that were created and releases prov
+      CryptAcquireContext(&prov, new_key_id.c_str(), NULL, PROV_RSA_FULL,
+                          CRYPT_SILENT | CRYPT_DELETEKEYSET);
+    }
+  }
+
+  return result;
 }
 
 }  // namespace net