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// Copyright (c) 2012 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 "crypto/symmetric_key.h"
#include <nss.h>
#include <pk11pub.h>
#include <stddef.h>
#include "base/logging.h"
#include "crypto/nss_util.h"
#include "crypto/scoped_nss_types.h"
namespace crypto {
SymmetricKey::~SymmetricKey() {}
// static
SymmetricKey* SymmetricKey::GenerateRandomKey(Algorithm algorithm,
size_t key_size_in_bits) {
DCHECK_EQ(AES, algorithm);
EnsureNSSInit();
// Whitelist supported key sizes to avoid accidentaly relying on
// algorithms available in NSS but not BoringSSL and vice
// versa. Note that BoringSSL does not support AES-192.
if (key_size_in_bits != 128 && key_size_in_bits != 256)
return NULL;
ScopedPK11Slot slot(PK11_GetInternalSlot());
if (!slot.get())
return NULL;
PK11SymKey* sym_key = PK11_KeyGen(slot.get(), CKM_AES_KEY_GEN, NULL,
key_size_in_bits / 8, NULL);
if (!sym_key)
return NULL;
return new SymmetricKey(sym_key);
}
// static
SymmetricKey* SymmetricKey::DeriveKeyFromPassword(Algorithm algorithm,
const std::string& password,
const std::string& salt,
size_t iterations,
size_t key_size_in_bits) {
EnsureNSSInit();
if (salt.empty() || iterations == 0 || key_size_in_bits == 0)
return NULL;
if (algorithm == AES) {
// Whitelist supported key sizes to avoid accidentaly relying on
// algorithms available in NSS but not BoringSSL and vice
// versa. Note that BoringSSL does not support AES-192.
if (key_size_in_bits != 128 && key_size_in_bits != 256)
return NULL;
}
SECItem password_item;
password_item.type = siBuffer;
password_item.data = reinterpret_cast<unsigned char*>(
const_cast<char *>(password.data()));
password_item.len = password.size();
SECItem salt_item;
salt_item.type = siBuffer;
salt_item.data = reinterpret_cast<unsigned char*>(
const_cast<char *>(salt.data()));
salt_item.len = salt.size();
SECOidTag cipher_algorithm =
algorithm == AES ? SEC_OID_AES_256_CBC : SEC_OID_HMAC_SHA1;
ScopedSECAlgorithmID alg_id(PK11_CreatePBEV2AlgorithmID(SEC_OID_PKCS5_PBKDF2,
cipher_algorithm,
SEC_OID_HMAC_SHA1,
key_size_in_bits / 8,
iterations,
&salt_item));
if (!alg_id.get())
return NULL;
ScopedPK11Slot slot(PK11_GetInternalSlot());
if (!slot.get())
return NULL;
PK11SymKey* sym_key = PK11_PBEKeyGen(slot.get(), alg_id.get(), &password_item,
PR_FALSE, NULL);
if (!sym_key)
return NULL;
return new SymmetricKey(sym_key);
}
// static
SymmetricKey* SymmetricKey::Import(Algorithm algorithm,
const std::string& raw_key) {
EnsureNSSInit();
if (algorithm == AES) {
// Whitelist supported key sizes to avoid accidentaly relying on
// algorithms available in NSS but not BoringSSL and vice
// versa. Note that BoringSSL does not support AES-192.
if (raw_key.size() != 128/8 && raw_key.size() != 256/8)
return NULL;
}
CK_MECHANISM_TYPE cipher =
algorithm == AES ? CKM_AES_CBC : CKM_SHA_1_HMAC;
SECItem key_item;
key_item.type = siBuffer;
key_item.data = reinterpret_cast<unsigned char*>(
const_cast<char *>(raw_key.data()));
key_item.len = raw_key.size();
ScopedPK11Slot slot(PK11_GetInternalSlot());
if (!slot.get())
return NULL;
// The exact value of the |origin| argument doesn't matter to NSS as long as
// it's not PK11_OriginFortezzaHack, so we pass PK11_OriginUnwrap as a
// placeholder.
PK11SymKey* sym_key = PK11_ImportSymKey(slot.get(), cipher, PK11_OriginUnwrap,
CKA_ENCRYPT, &key_item, NULL);
if (!sym_key)
return NULL;
return new SymmetricKey(sym_key);
}
bool SymmetricKey::GetRawKey(std::string* raw_key) {
SECStatus rv = PK11_ExtractKeyValue(key_.get());
if (SECSuccess != rv)
return false;
SECItem* key_item = PK11_GetKeyData(key_.get());
if (!key_item)
return false;
raw_key->assign(reinterpret_cast<char*>(key_item->data), key_item->len);
return true;
}
SymmetricKey::SymmetricKey(PK11SymKey* key) : key_(key) {
DCHECK(key);
}
} // namespace crypto
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