/* * DLIES * (C) 1999-2007 Jack Lloyd * * Distributed under the terms of the Botan license */ #include <botan/dlies.h> #include <botan/look_pk.h> #include <botan/xor_buf.h> namespace Botan { /* * DLIES_Encryptor Constructor */ DLIES_Encryptor::DLIES_Encryptor(const PK_Key_Agreement_Key& k, KDF* kdf_obj, MessageAuthenticationCode* mac_obj, u32bit mac_kl) : key(k), kdf(kdf_obj), mac(mac_obj), mac_keylen(mac_kl) { } 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.is_empty()) throw Invalid_State("DLIES: The other key was never set"); MemoryVector<byte> v = key.public_value(); SecureVector<byte> out(v.size() + length + mac->OUTPUT_LENGTH); out.copy(v, v.size()); out.copy(v.size(), in, length); SecureVector<byte> vz(v, key.derive_key(other_key, other_key.size())); 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 + v.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& k, KDF* kdf_obj, MessageAuthenticationCode* mac_obj, u32bit mac_kl) : key(k), kdf(kdf_obj), mac(mac_obj), mac_keylen(mac_kl) { } DLIES_Decryptor::~DLIES_Decryptor() { delete kdf; delete mac; } /* * DLIES Decryption */ SecureVector<byte> DLIES_Decryptor::dec(const byte msg[], u32bit length) const { const u32bit public_len = key.public_value().size(); if(length < public_len + mac->OUTPUT_LENGTH) throw Decoding_Error("DLIES decryption: ciphertext is too short"); const u32bit CIPHER_LEN = length - public_len - mac->OUTPUT_LENGTH; SecureVector<byte> v(msg, public_len); SecureVector<byte> C(msg + public_len, CIPHER_LEN); SecureVector<byte> T(msg + public_len + CIPHER_LEN, mac->OUTPUT_LENGTH); SecureVector<byte> vz(v, key.derive_key(v, v.size())); 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 Integrity_Failure("DLIES: message authentication failed"); xor_buf(C, K.begin() + mac_keylen, C.size()); return C; } }