// Decryption functions
bool BotanRSA::decrypt(PrivateKey* privateKey, const ByteString& encryptedData,
ByteString& data, const AsymMech::Type padding)
{
// Check if the private key is the right type
if (!privateKey->isOfType(BotanRSAPrivateKey::type))
{
ERROR_MSG("Invalid key type supplied");
return false;
}
std::string eme;
switch (padding)
{
case AsymMech::RSA_PKCS:
eme = "PKCS1v15";
break;
case AsymMech::RSA_PKCS_OAEP:
eme = "EME1(SHA-160)";
break;
case AsymMech::RSA:
eme = "Raw";
break;
default:
ERROR_MSG("Invalid padding mechanism supplied (%i)", padding);
return false;
}
BotanRSAPrivateKey* pk = (BotanRSAPrivateKey*) privateKey;
Botan::RSA_PrivateKey* botanKey = pk->getBotanKey();
if (!botanKey)
{
ERROR_MSG("Could not get the Botan private key");
return false;
}
Botan::PK_Decryptor_EME* decryptor = NULL;
try
{
decryptor = new Botan::PK_Decryptor_EME(*botanKey, eme);
}
catch (...)
{
ERROR_MSG("Could not create the decryptor token");
return false;
}
// Perform the decryption operation
#if BOTAN_VERSION_MINOR == 11
Botan::secure_vector<Botan::byte> decResult;
#else
Botan::SecureVector<Botan::byte> decResult;
#endif
try
{
decResult = decryptor->decrypt(encryptedData.const_byte_str(), encryptedData.size());
}
catch (...)
{
ERROR_MSG("Could not decrypt the data");
delete decryptor;
return false;
}
// Return the result
if (padding == AsymMech::RSA)
{
// We compensate that Botan removes leading zeros
int modSize = pk->getN().size();
int decSize = decResult.size();
data.resize(modSize);
#if BOTAN_VERSION_MINOR == 11
memcpy(&data[0] + modSize - decSize, decResult.data(), decSize);
#else
memcpy(&data[0] + modSize - decSize, decResult.begin(), decSize);
#endif
}
else
{
data.resize(decResult.size());
#if BOTAN_VERSION_MINOR == 11
memcpy(&data[0], decResult.data(), decResult.size());
#else
memcpy(&data[0], decResult.begin(), decResult.size());
#endif
}
delete decryptor;
return true;
}
// Wrap/Unwrap keys
bool BotanAES::wrapKey(const SymmetricKey* key, const SymWrap::Type mode, const ByteString& in, ByteString& out)
{
// Check key bit length; AES only supports 128, 192 or 256 bit keys
if ((key->getBitLen() != 128) &&
(key->getBitLen() != 192) &&
(key->getBitLen() != 256))
{
ERROR_MSG("Invalid AES key length (%d bits)", key->getBitLen());
return false;
}
// Determine the wrapping mode
if (mode == SymWrap::AES_KEYWRAP)
{
// RFC 3394 AES key wrap
if (in.size() < 16)
{
ERROR_MSG("key data to wrap too small");
return false;
}
if ((in.size() % 8) != 0)
{
ERROR_MSG("key data to wrap not aligned");
return false;
}
#if BOTAN_VERSION_MINOR == 11
Botan::secure_vector<Botan::byte> data(in.size());
memcpy(data.data(), in.const_byte_str(), in.size());
Botan::secure_vector<Botan::byte> wrapped;
#else
Botan::MemoryVector<Botan::byte> data(in.size());
memcpy(data.begin(), in.const_byte_str(), in.size());
Botan::SecureVector<Botan::byte> wrapped;
#endif
Botan::SymmetricKey botanKey = Botan::SymmetricKey(key->getKeyBits().const_byte_str(), key->getKeyBits().size());
Botan::Algorithm_Factory& af = Botan::global_state().algorithm_factory();
try
{
wrapped = Botan::rfc3394_keywrap(data, botanKey, af);
}
catch (...)
{
ERROR_MSG("AES key wrap failed");
return false;
}
out.resize(wrapped.size());
#if BOTAN_VERSION_MINOR == 11
memcpy(&out[0], wrapped.data(), out.size());
#else
memcpy(&out[0], wrapped.begin(), out.size());
#endif
return true;
}
#ifdef HAVE_AES_KEY_WRAP_PAD
else if (mode == SymWrap::AES_KEYWRAP_PAD)
{
// RFC 5649 AES key wrap with pad
#if BOTAN_VERSION_MINOR == 11
Botan::secure_vector<Botan::byte> data(in.size());
memcpy(data.data(), in.const_byte_str(), in.size());
Botan::secure_vector<Botan::byte> wrapped;
#else
Botan::MemoryVector<Botan::byte> data(in.size());
memcpy(data.begin(), in.const_byte_str(), in.size());
Botan::SecureVector<Botan::byte> wrapped;
#endif
Botan::SymmetricKey botanKey = Botan::SymmetricKey(key->getKeyBits().const_byte_str(), key->getKeyBits().size());
Botan::Algorithm_Factory& af = Botan::global_state().algorithm_factory();
try
{
wrapped = Botan::rfc5649_keywrap(data, botanKey, af);
}
catch (...)
{
ERROR_MSG("AES key wrap failed");
return false;
}
out.resize(wrapped.size());
#if BOTAN_VERSION_MINOR == 11
memcpy(&out[0], wrapped.data(), out.size());
#else
memcpy(&out[0], wrapped.begin(), out.size());
#endif
return true;
}
#endif
else
{
ERROR_MSG("unknown AES key wrap mode %i", mode);
return false;
}
}
