/*
*				libCryp.c
*
* Library of encryption (std) for Citadel.
*/
/*
*				history
*
* 91????? HAW	Hash moved to Tools.c.
* 87Aug06 HAW  Hash added.
* 85Nov15 HAW  Created.
*/
#include "ctdl.h"
/*
*				contents
*
*	crypte()		encrypts/decrypts data blocks
*/
extern CONFIG cfg;		/* Configuration variables      */
/*
* crypte()
*
* encrypts/decrypts data blocks
*
* This was at first using a full multiply/add pseudo-random sequence
* generator, but 8080s don't like to multiply.  Slowed down I/O
* noticably.  Rewrote for speed.
*
* 84Sep04 HAW  I'll just use it......
*/
void crypte(void *buf, unsigned len, unsigned seed)
  {
  static AN_UNSIGNED *b;      /* Make this static for speed (I guess),*/
  static  int c, s;		/* since register variables not around  */
  if( cfg.cryptSeed == 0 ) return;
  seed	= (seed + cfg.cryptSeed) & 0xFF;
  b		= (AN_UNSIGNED *) buf;
  c		= len;
  s		= seed;
  for (;  c;  c--)
    {
    *b++   ^= s;
    s       = (s + CRYPTADD)  &  0xFF;
    
    }
  
  }