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/*
* DLIES
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/dlies.h>
#include <botan/internal/xor_buf.h>
namespace Botan {
/*
* DLIES_Encryptor Constructor
*/
DLIES_Encryptor::DLIES_Encryptor(const PK_Key_Agreement_Key& key,
KDF* kdf_obj,
MessageAuthenticationCode* mac_obj,
u32bit mac_kl) :
ka(key, "Raw"),
kdf(kdf_obj),
mac(mac_obj),
mac_keylen(mac_kl)
{
my_key = key.public_value();
}
DLIES_Encryptor::~DLIES_Encryptor()
{
delete kdf;
delete mac;
}
/*
* DLIES Encryption
*/
SecureVector<byte> DLIES_Encryptor::enc(const byte in[], u32bit length,
RandomNumberGenerator&) const
{
if(length > maximum_input_size())
throw Invalid_Argument("DLIES: Plaintext too large");
if(other_key.empty())
throw Invalid_State("DLIES: The other key was never set");
SecureVector<byte> out(my_key.size() + length + mac->OUTPUT_LENGTH);
out.copy(my_key, my_key.size());
out.copy(my_key.size(), in, length);
SecureVector<byte> vz(my_key, ka.derive_key(0, other_key).bits_of());
const u32bit K_LENGTH = length + mac_keylen;
OctetString K = kdf->derive_key(K_LENGTH, vz, vz.size());
if(K.length() != K_LENGTH)
throw Encoding_Error("DLIES: KDF did not provide sufficient output");
byte* C = out + my_key.size();
xor_buf(C, K.begin() + mac_keylen, length);
mac->set_key(K.begin(), mac_keylen);
mac->update(C, length);
for(u32bit j = 0; j != 8; ++j)
mac->update(0);
mac->final(C + length);
return out;
}
/*
* Set the other parties public key
*/
void DLIES_Encryptor::set_other_key(const MemoryRegion<byte>& ok)
{
other_key = ok;
}
/*
* Return the max size, in bytes, of a message
*/
u32bit 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,
u32bit mac_kl) :
ka(key, "Raw"),
kdf(kdf_obj),
mac(mac_obj),
mac_keylen(mac_kl)
{
my_key = key.public_value();
}
DLIES_Decryptor::~DLIES_Decryptor()
{
delete kdf;
delete mac;
}
/*
* DLIES Decryption
*/
SecureVector<byte> DLIES_Decryptor::dec(const byte msg[], u32bit length) const
{
if(length < my_key.size() + mac->OUTPUT_LENGTH)
throw Decoding_Error("DLIES decryption: ciphertext is too short");
const u32bit CIPHER_LEN = length - my_key.size() - mac->OUTPUT_LENGTH;
SecureVector<byte> v(msg, my_key.size());
SecureVector<byte> C(msg + my_key.size(), CIPHER_LEN);
SecureVector<byte> T(msg + my_key.size() + CIPHER_LEN, mac->OUTPUT_LENGTH);
SecureVector<byte> vz(v, ka.derive_key(0, v).bits_of());
const u32bit K_LENGTH = C.size() + mac_keylen;
OctetString K = kdf->derive_key(K_LENGTH, vz, vz.size());
if(K.length() != K_LENGTH)
throw Encoding_Error("DLIES: KDF did not provide sufficient output");
mac->set_key(K.begin(), mac_keylen);
mac->update(C);
for(u32bit j = 0; j != 8; ++j)
mac->update(0);
SecureVector<byte> T2 = mac->final();
if(T != T2)
throw Decoding_Error("DLIES: message authentication failed");
xor_buf(C, K.begin() + mac_keylen, C.size());
return C;
}
}
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