applied cryptography - protocols, algorithms, and source code in c

0x2ba9c55d 0x741831f6 0x7a325381 0x28958677 0x61d809cc

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Unformatted text preview: ask to next bit */ short mult8(a, b, gen) short a, b; /* operands for multiply */ short gen; /* irreducible polynomial generating Galois Field */ { short product = 0; /* result of multiplication */ while(b != 0) { if (b & 01) product ^= a; a <<= 1; if (a >= SIZE) a ^= gen; b >>= 1; } return(product); } /* while multiplier is non–zero */ /* add multiplicand if LSB of b set */ shift multiplicand one place */ and modulo reduce if needed */ shift multiplier one place */ /* /* /* short exp8(base, exponent, gen) short base; /* base of exponentiation */ short exponent; /* exponent */ short gen; /* irreducible polynomial generating Galois Field */ { short accum = base; /* superincreasing sequence of base */ short result = 1; /* result of exponentiation */ if (base == 0) return(0); /* if zero base specified then /* the result is “0” if base = 0 */ */ while (exponent != 0) { /* repeat while exponent non–zero */ if (( exponent & 0×0001) == 0×0001) /* multiply if exp 1 */ result = mult8(result, accum, gen); exponent >>= 1; /* shift exponent to next digit */ accum = mult8(accum, accum, gen); /* & square */ } return(result); } void loki_key(loki_ctx *c, unsigned char *key){ setlokikey(c,key); } void loki_enc(loki_ctx *c, unsigned char *data, int blocks){ unsigned char *cp; int i; cp = data; for(i=0;i<blocks;i++){ enloki(c,cp); cp+=8; } } void loki_dec(loki_ctx *c, unsigned char *data, int blocks){ unsigned char *cp; int i; cp = data; for(i=0;i<blocks;i++){ deloki(c,cp); cp+=8; } } void main(void){ loki_ctx unsigned unsigned unsigned int i; lc; long data[10]; char *cp; char key = {0,1,2,3,4,5,6,7}; for(i=0;i<10;i++) data[i]=i; loki_key(&amplc,key); cp = (char *)data; loki_enc(&amplc,cp,5); for(i=0;i<10;i+=2) printf(“Block %01d = %08lx %08lx\n”, i/2,data[i],data[i+1]); loki_dec(&amplc,cp,1); loki_dec(&amplc,cp+8,4); for(i=0;i<10;i+=2) printf(“Block %01d = %08lx %08lx\n”, i/2,data[i],data[i+1]); } IDEA typedef typedef typedef typedef typedef unsigned char boolean; /* values are TRUE or FALSE */ unsigned char byte; /* values are 0–255 */ byte *byteptr; /* pointer to byte */ char *string;/* pointer to ASCII character string */ unsigned short word16; /* values are 0–65535 */ typedef unsigned long word32; /* values are 0–4294967295 */ #ifndef TRUE #define FALSE 0 #define TRUE (!FALSE) #endif /* if TRUE not already defined */ #ifndef min /* #define min(a,b) #define max(a,b) #endif /...
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This note was uploaded on 10/18/2010 for the course MATH CS 301 taught by Professor Aliulger during the Fall '10 term at Koç University.

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