/*
 *	Plan 9 DES encryption.
 */

#include "des.h"

int
encrypt(void *key, void *data, int len)
{
	int	n;
	int	r;
	int	i;
	char	*b;

	if (len < DESBLOCKLEN)
		return 0;

	deskey(key);

	len -= DESBLOCKLEN;
	n = len / 7 + 1;
	r = len % 7;

	b = data;

	for (i = 0; i < n; i++)
	{
		des(b, 0);
		b += 7;
	}

	if (r)
	{
		b = data;
		des(&b[len], 0);
	}

	return 1;
}

/*
 *	Plan 9 DES decryption.
 */
int
decrypt(void *key, void *data, int len)
{
	int	n;
	int	r;
	int	i;
	char	*b;

	if (len < DESBLOCKLEN)
		return 0;

	deskey(key);

	len -= DESBLOCKLEN;
	n = len / 7 + 1;
	r = len % 7;

	b = data;

	if (r)
		des(&b[len], 1);

	b = &b[len - r];

	for (i = 0; i < n; i++)
	{
		des(b, 1);
		b -= 7;
	}

	return 1;
}

/*
 *	Convert a Plan 9 key to a DES key.
 */
uchar	*
des9key(uchar *key)
{
	int		i;
	int		m1[]	= { 0x00, 0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F };
	int		m2[]	= { 0x00, 0xFC, 0xF8, 0xF0, 0xE0, 0xC0, 0x80 };
	static uchar	nkey[DESKEYPLEN];

	nkey[0] = key[0] & 0xFE;

	for (i = 1; i < 7; i++)
		nkey[i] = (key[i - 1] & m1[i]) << 8 - i | (key[i] & m2[i]) >> i;

	nkey[7] = (key[6] & 0x7F) << 1;


	return nkey;
}

/*
 *	Securenet challenge encryption.
 */
int
netcrypt(void *key, void *data)
{
	uchar	b[DESBLOCKLEN];

	strncpy((char *)b, (char *)data, DESBLOCKLEN);

	if (!encrypt(des9key(key), b, DESBLOCKLEN))
		return 0;

	sprint((char *)data, "%.2ux%.2ux%.2ux%.2ux", b[0], b[1], b[2], b[3]);
	return 1;
}

/*
 *	Map a hexadecimal string to Securenet decimal string.
 */
void
sechex(char *buf)
{
	char	*p;

	for (p = buf; *p != '\0'; p++)
	{
		switch (*p)
		{
		case 'A':
		case 'B':
		case 'C':
		case 'a':
		case 'b':
		case 'c':
			*p = '2';
			break;

		case 'D':
		case 'E':
		case 'F':
		case 'd':
		case 'e':
		case 'f':
			*p = '3';
			break;
		}
	}
}