60 lines
1.1 KiB
C
60 lines
1.1 KiB
C
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#include "spn.h"
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unsigned char do_perm(unsigned char w, unsigned char perm[8]) {
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unsigned char output = 0x00;
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for (int i = 0; i < 8; i++) {
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output |= (w & (1 << i)) >> i << perm[i];
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}
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return output;
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}
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unsigned char do_subst(unsigned char w, unsigned char subst[16]) {
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unsigned char output = 0x00;
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output |= subst[(w & 0xF)];
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output |= subst[(w & 0xF0) >> 4] << 4;
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return output;
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}
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unsigned char encrypt(
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unsigned char w,
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unsigned short key,
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unsigned char perm[8],
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unsigned char subst[16]
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) {
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unsigned char k0 = key & 0xFF;
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unsigned char k1 = (key & 0xFF00) >> 8;
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w ^= k0;
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w = do_subst(w, subst);
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w = do_perm(w, perm);
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w ^= k1;
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w = do_subst(w, subst);
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w = do_perm(w, perm);
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return w;
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}
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unsigned char decrypt(
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unsigned char w,
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unsigned short key,
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unsigned char perm[8],
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unsigned char subst[16]
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) {
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unsigned char k0 = key & 0xFF;
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unsigned char k1 = (key & 0xFF00) >> 8;
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w = do_perm(w, perm);
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w = do_subst(w, subst);
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w ^= k1;
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w = do_perm(w, perm);
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w = do_subst(w, subst);
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w ^= k0;
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return w;
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}
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