Adding Stream Encryption Algorithms

The required constant definitions are as follows:

#define MODULE_NAME ARC4       /* Name of algorithm */
#define BLOCK_SIZE 1           /* Will always be 1 for a stream cipher */
#define KEY_SIZE 0             /* Size of key in bytes (0 if not fixed size) */

The C structure must be named stream_state:

typedef struct {
     ... whatever state variables you need ...
} stream_state;

There are three functions that need to be written: to initialize the algorithm's state, and to encrypt and decrypt a single block.

• void stream_init(stream_state *self, unsigned char *key, int keylen);
• void stream_encrypt(stream_state *self, unsigned char *block, int length);
• void stream_decrypt(stream_state *self, unsigned char *block, int length);

Put #include "stream_template.c" at the end of the file to include the actual implementation of the module.