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/*
* Adding an application specific engine
* (C) 2004,2008 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/stream_cipher.h>
#include <botan/engine.h>
using namespace Botan;
class XOR_Cipher : public StreamCipher
{
public:
void clear() throw() { mask.destroy(); mask_pos = 0; }
// what we want to call this cipher
std::string name() const { return "XOR"; }
// return a new object of this type
StreamCipher* clone() const { return new XOR_Cipher; }
XOR_Cipher() : StreamCipher(1, 32) { mask_pos = 0; }
private:
void cipher(const byte in[], byte out[], u32bit length)
{
for(u32bit j = 0; j != length; j++)
{
out[j] = in[j] ^ mask[mask_pos];
mask_pos = (mask_pos + 1) % mask.size();
}
}
void key_schedule(const byte key[], u32bit length)
{
mask.set(key, length);
}
SecureVector<byte> mask;
u32bit mask_pos;
};
class Application_Engine : public Engine
{
public:
std::string provider_name() const { return "application"; }
StreamCipher* find_stream_cipher(const SCAN_Name& request,
Algorithm_Factory&) const
{
if(request.algo_name() == "XOR")
return new XOR_Cipher;
return 0;
}
};
#include <botan/botan.h>
#include <iostream>
#include <string>
int main()
{
Botan::LibraryInitializer init;
global_state().algorithm_factory().add_engine(
new Application_Engine);
// a hex key value
SymmetricKey key("010203040506070809101112AAFF");
/*
Since stream ciphers are typically additive, the encryption and
decryption ops are the same, so this isn't terribly interesting.
If this where a block cipher you would have to add a cipher mode and
padding method, such as "/CBC/PKCS7".
*/
Pipe enc(get_cipher("XOR", key, ENCRYPTION), new Hex_Encoder);
Pipe dec(new Hex_Decoder, get_cipher("XOR", key, DECRYPTION));
// I think the pigeons are actually asleep at midnight...
std::string secret = "The pigeon flys at midnight.";
std::cout << "The secret message is '" << secret << "'" << std::endl;
enc.process_msg(secret);
std::string cipher = enc.read_all_as_string();
std::cout << "The encrypted secret message is " << cipher << std::endl;
dec.process_msg(cipher);
secret = dec.read_all_as_string();
std::cout << "The decrypted secret message is '"
<< secret << "'" << std::endl;
return 0;
}
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