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/*
* DLIES
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/dlies.h>
namespace Botan {
/*
* DLIES_Encryptor Constructor
*/
DLIES_Encryptor::DLIES_Encryptor(const PK_Key_Agreement_Key& key,
KDF* kdf_obj,
MessageAuthenticationCode* mac_obj,
size_t mac_kl) :
m_ka(key, "Raw"),
m_kdf(kdf_obj),
m_mac(mac_obj),
m_mac_keylen(mac_kl)
{
m_my_key = key.public_value();
}
/*
* DLIES Encryption
*/
std::vector<byte> DLIES_Encryptor::enc(const byte in[], size_t length,
RandomNumberGenerator&) const
{
if(length > maximum_input_size())
throw Invalid_Argument("DLIES: Plaintext too large");
if(m_other_key.empty())
throw Invalid_State("DLIES: The other key was never set");
secure_vector<byte> out(m_my_key.size() + length + m_mac->output_length());
buffer_insert(out, 0, m_my_key);
buffer_insert(out, m_my_key.size(), in, length);
secure_vector<byte> vz(m_my_key.begin(), m_my_key.end());
vz += m_ka.derive_key(0, m_other_key).bits_of();
const size_t K_LENGTH = length + m_mac_keylen;
secure_vector<byte> K = m_kdf->derive_key(K_LENGTH, vz);
if(K.size() != K_LENGTH)
throw Encoding_Error("DLIES: KDF did not provide sufficient output");
byte* C = &out[m_my_key.size()];
m_mac->set_key(K.data(), m_mac_keylen);
xor_buf(C, &K[m_mac_keylen], length);
m_mac->update(C, length);
for(size_t j = 0; j != 8; ++j)
m_mac->update(0);
m_mac->final(C + length);
return unlock(out);
}
/*
* Set the other parties public key
*/
void DLIES_Encryptor::set_other_key(const std::vector<byte>& ok)
{
m_other_key = ok;
}
/*
* Return the max size, in bytes, of a message
*/
size_t DLIES_Encryptor::maximum_input_size() const
{
return 32;
}
/*
* DLIES_Decryptor Constructor
*/
DLIES_Decryptor::DLIES_Decryptor(const PK_Key_Agreement_Key& key,
KDF* kdf_obj,
MessageAuthenticationCode* mac_obj,
size_t mac_kl) :
m_ka(key, "Raw"),
m_kdf(kdf_obj),
m_mac(mac_obj),
m_mac_keylen(mac_kl)
{
m_my_key = key.public_value();
}
/*
* DLIES Decryption
*/
secure_vector<byte> DLIES_Decryptor::dec(const byte msg[], size_t length) const
{
if(length < m_my_key.size() + m_mac->output_length())
throw Decoding_Error("DLIES decryption: ciphertext is too short");
const size_t CIPHER_LEN = length - m_my_key.size() - m_mac->output_length();
std::vector<byte> v(msg, msg + m_my_key.size());
secure_vector<byte> C(msg + m_my_key.size(), msg + m_my_key.size() + CIPHER_LEN);
secure_vector<byte> T(msg + m_my_key.size() + CIPHER_LEN,
msg + m_my_key.size() + CIPHER_LEN + m_mac->output_length());
secure_vector<byte> vz(msg, msg + m_my_key.size());
vz += m_ka.derive_key(0, v).bits_of();
const size_t K_LENGTH = C.size() + m_mac_keylen;
secure_vector<byte> K = m_kdf->derive_key(K_LENGTH, vz);
if(K.size() != K_LENGTH)
throw Encoding_Error("DLIES: KDF did not provide sufficient output");
m_mac->set_key(K.data(), m_mac_keylen);
m_mac->update(C);
for(size_t j = 0; j != 8; ++j)
m_mac->update(0);
secure_vector<byte> T2 = m_mac->final();
if(T != T2)
throw Decoding_Error("DLIES: message authentication failed");
xor_buf(C, K.data() + m_mac_keylen, C.size());
return C;
}
}
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