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