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// 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/crypto/capi_util.h"
#include "base/logging.h"
#include "base/string_piece.h"
#include "base/string_util.h"
#include "base/utf_string_conversions.h"
namespace net {
// Assigns the contents of a CERT_PUBLIC_KEY_INFO structure for the signing
// key in |prov| to |output|. Returns true if encoding was successful.
bool GetSubjectPublicKeyInfo(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;
output->resize(size);
PCERT_PUBLIC_KEY_INFO public_key_casted =
reinterpret_cast<PCERT_PUBLIC_KEY_INFO>(&(*output)[0]);
ok = CryptExportPublicKeyInfoEx(prov, AT_KEYEXCHANGE, X509_ASN_ENCODING,
szOID_RSA_RSA, 0, NULL, public_key_casted,
&size);
DCHECK(ok);
if (!ok)
return false;
output->resize(size);
return true;
}
// Generates a DER encoded SignedPublicKeyAndChallenge structure from the
// signing key of |prov| and the specified ASCII |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::wstring wide_challenge = ASCIIToWide(challenge);
std::vector<BYTE> spki;
if (!GetSubjectPublicKeyInfo(prov, &spki))
return false;
// PublicKeyAndChallenge ::= SEQUENCE {
// spki SubjectPublicKeyInfo,
// challenge IA5STRING
// }
CERT_KEYGEN_REQUEST_INFO pkac;
pkac.dwVersion = CERT_KEYGEN_REQUEST_V1;
pkac.SubjectPublicKeyInfo =
*reinterpret_cast<PCERT_PUBLIC_KEY_INFO>(&spki[0]);
pkac.pwszChallengeString = const_cast<wchar_t*>(wide_challenge.c_str());
CRYPT_ALGORITHM_IDENTIFIER sig_alg;
memset(&sig_alg, 0, sizeof(sig_alg));
sig_alg.pszObjId = szOID_RSA_MD5RSA;
BOOL ok;
DWORD size = 0;
std::vector<BYTE> signed_pkac;
ok = CryptSignAndEncodeCertificate(prov, AT_KEYEXCHANGE, X509_ASN_ENCODING,
X509_KEYGEN_REQUEST_TO_BE_SIGNED,
&pkac, &sig_alg, NULL,
NULL, &size);
DCHECK(ok);
if (!ok)
return false;
signed_pkac.resize(size);
ok = CryptSignAndEncodeCertificate(prov, AT_KEYEXCHANGE, X509_ASN_ENCODING,
X509_KEYGEN_REQUEST_TO_BE_SIGNED,
&pkac, &sig_alg, NULL,
&signed_pkac[0], &size);
DCHECK(ok);
if (!ok)
return false;
output->assign(reinterpret_cast<char*>(&signed_pkac[0]), 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;
// RPC_WSTR is unsigned short*. wchar_t is a built-in type of Visual C++,
// so the type cast is necessary.
result.assign(reinterpret_cast<wchar_t*>(rpc_string));
RpcStringFree(&rpc_string);
return result;
}
std::string KeygenHandler::GenKeyAndSignChallenge() {
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 key type
// requested or the key size 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 = base::CryptAcquireContextLocked(&prov, new_key_id.c_str(), NULL,
PROV_RSA_FULL,
CRYPT_SILENT | CRYPT_NEWKEYSET);
if (ok || 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";
}
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.
base::CryptAcquireContextLocked(&prov, new_key_id.c_str(), NULL,
PROV_RSA_FULL,
CRYPT_SILENT | CRYPT_DELETEKEYSET);
}
}
return result;
}
} // namespace net
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