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