/*
 * Copyright (C) 2005 Computer Smiths Pty Ltd.
 *
 * This library implementes the triple rot13 encryption algorithm
 * as devised by Brendan Gregg.
 *
 * This library is for demosatration purposes only, and should not be used
 * in security related uses. It is known to have been broken.
 *
 * WARNING *** This algorithm is known to be decryptable *** WARNING
 *
 * 12-Mar-2005	Rex di Bona	Created this.
 */

#include <sys/types.h>
#include <strings.h>
#include <stdio.h>
#include <errno.h>

#if 0
int	_lib_version = 1;

void
_init()
{
}

void
_fini()
{
}
#endif

static void
rot13str(char *str, int len)
{
	for (; len--; str++) {
		char c = *str;

		/* this should be a table lookup for speed */
		if (c >= 'a' && c <= 'm') {
			c += 13;
		} else if (c >= 'n' && c <= 'z') {
			c -= 13;
		} else if (c >= 'A' && c <= 'M') {
			c += 13;
		} else if (c >= 'N' && c <= 'Z') {
			c -= 13;
		} else {
			; /* nothing - don't change c */
		}
		*str = c;
	}
}

char *
crypt_genhash_impl(char *ctbuffer, size_t ctbuflen, const char *plaintext, const char *salt, const char **params)
{
	int	hlen;
	int	rounds = 3;
	int	debug = 0;
	char	*s = "$3rot13$";

	if (params != NULL) {
		const char	*p;

		while (p = *params++) {
			if (strcasecmp(p, "debug") == 0) {
				debug++;
			} else if (strncasecmp(p, "rounds=", 7) == 0) {
				rounds = atoi(p+7);
			} else {
				fprintf(stderr, "Arg is '%s'\n", p);
			}
		}
	}
	hlen = strlen(s);
	if (plaintext == NULL) {
		errno = EFAULT;
		return NULL;
	}
	if (ctbuflen <= hlen + strlen(plaintext)) {
		errno = ENOMEM;
		return NULL;
	}
	strncpy(ctbuffer, s, hlen);
	strncpy(ctbuffer + hlen, plaintext, ctbuflen);
	while (rounds-- > 0) {
		rot13str(ctbuffer + hlen, ctbuflen);
		if (debug) {
			fprintf(stderr, "buffer: '%s'\n", ctbuffer);
		}
	}
	return ctbuffer;
}

char *
crypt_gensalt_impl(char *csbuffer, size_t csbuflen, const char *oldsalt, const char *userinfo, const char **params)
{
	strncpy(csbuffer, "$3rot13$XXXX$", csbuflen);
	return csbuffer;
}