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