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63 lines
2.0 KiB
C++
63 lines
2.0 KiB
C++
// Purpose: Header file for the C++ ICE encryption class.
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// Taken from public domain code, as written by Matthew Kwan - July 1996
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// http://www.darkside.com.au/ice/
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#ifndef _IceKey_H
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#define _IceKey_H
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/*
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The IceKey class is used for encrypting and decrypting 64-bit blocks of data
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with the ICE (Information Concealment Engine) encryption algorithm.
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The constructor creates a new IceKey object that can be used to encrypt and decrypt data.
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The level of encryption determines the size of the key, and hence its speed.
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Level 0 uses the Thin-ICE variant, which is an 8-round cipher taking an 8-byte key.
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This is the fastest option, and is generally considered to be at least as secure as DES,
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although it is not yet certain whether it is as secure as its key size.
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For levels n greater than zero, a 16n-round cipher is used, taking 8n-byte keys.
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Although not as fast as level 0, these are very very secure.
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Before an IceKey can be used to encrypt data, its key schedule must be set with the set() member function.
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The length of the key required is determined by the level, as described above.
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The member functions encrypt() and decrypt() encrypt and decrypt respectively data
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in blocks of eight chracters, using the specified key.
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Two functions keySize() and blockSize() are provided
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which return the key and block size respectively, measured in bytes.
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The key size is determined by the level, while the block size is always 8.
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The destructor zeroes out and frees up all memory associated with the key.
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*/
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class IceSubkey;
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class IceKey {
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public:
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IceKey (int n);
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~IceKey ();
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void set (const unsigned char *key);
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void encrypt (const unsigned char *plaintext,
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unsigned char *ciphertext) const;
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void decrypt (const unsigned char *ciphertext,
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unsigned char *plaintext) const;
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int keySize () const;
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int blockSize () const;
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private:
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void scheduleBuild (unsigned short *k, int n,
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const int *keyrot);
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int _size;
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int _rounds;
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IceSubkey *_keysched;
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};
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#endif
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