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/*
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 *	Data Encryption Standard
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 *	D.P.Mitchell  83/06/08.
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 *
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 *	block_cipher(key, block, decrypting)
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 *
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 *	these routines use the non-standard 7 byte format
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 *	for DES keys.
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 */
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#include <u.h>
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#include <libc.h>
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#include <auth.h>
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#include <libsec.h>
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/*
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 * destructively encrypt the buffer, which
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 * must be at least 8 characters long.
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 */
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int
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encrypt(void *key, void *vbuf, int n)
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{
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	ulong ekey[32];
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	uchar *buf;
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	int i, r;
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	if(n < 8)
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		return 0;
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	key_setup(key, ekey);
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	buf = vbuf;
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	n--;
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	r = n % 7;
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	n /= 7;
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	for(i = 0; i < n; i++){
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		block_cipher(ekey, buf, 0);
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		buf += 7;
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	}
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	if(r)
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		block_cipher(ekey, buf - 7 + r, 0);
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	return 1;
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}
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/*
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 * destructively decrypt the buffer, which
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 * must be at least 8 characters long.
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 */
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int
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decrypt(void *key, void *vbuf, int n)
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{
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	ulong ekey[128];
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	uchar *buf;
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	int i, r;
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	if(n < 8)
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		return 0;
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	key_setup(key, ekey);
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	buf = vbuf;
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	n--;
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	r = n % 7;
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	n /= 7;
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	buf += n * 7;
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	if(r)
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		block_cipher(ekey, buf - 7 + r, 1);
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	for(i = 0; i < n; i++){
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		buf -= 7;
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		block_cipher(ekey, buf, 1);
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	}
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	return 1;
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}