68 lines
1 KiB
C
68 lines
1 KiB
C
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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 <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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}
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