/************************************************* * DLIES Source File * * (C) 1999-2007 Jack Lloyd * *************************************************/ #include #include #include #include #include namespace Botan { /************************************************* * DLIES_Encryptor Constructor * *************************************************/ DLIES_Encryptor::DLIES_Encryptor(const PK_Key_Agreement_Key& k, const std::string& kdf, const std::string& mac, u32bit mk_len) : key(k), kdf_algo(kdf), mac_algo(mac), MAC_KEYLEN(mk_len) { } /************************************************* * DLIES Encryption * *************************************************/ SecureVector DLIES_Encryptor::enc(const byte in[], u32bit length) 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"); std::auto_ptr kdf(get_kdf(kdf_algo)); std::auto_ptr mac(get_mac(mac_algo)); MemoryVector v = key.public_value(); SecureVector out(v.size() + length + mac->OUTPUT_LENGTH); out.copy(v, v.size()); out.copy(v.size(), in, length); SecureVector 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& 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, const std::string& kdf, const std::string& mac, u32bit mk_len) : key(k), kdf_algo(kdf), mac_algo(mac), MAC_KEYLEN(mk_len), PUBLIC_LEN(key.public_value().size()) { } /************************************************* * DLIES Decryption * *************************************************/ SecureVector DLIES_Decryptor::dec(const byte msg[], u32bit length) const { std::auto_ptr mac(get_mac(mac_algo)); if(length < PUBLIC_LEN + mac->OUTPUT_LENGTH) throw Decoding_Error("DLIES decryption: ciphertext is too short"); std::auto_ptr kdf(get_kdf(kdf_algo)); const u32bit CIPHER_LEN = length - PUBLIC_LEN - mac->OUTPUT_LENGTH; SecureVector v(msg, PUBLIC_LEN); SecureVector C(msg + PUBLIC_LEN, CIPHER_LEN); SecureVector T(msg + PUBLIC_LEN + CIPHER_LEN, mac->OUTPUT_LENGTH); SecureVector 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 T2 = mac->final(); if(T != T2) throw Integrity_Failure("DLIES: message authentication failed"); xor_buf(C, K.begin() + MAC_KEYLEN, C.size()); return C; } }