mirror of
https://github.com/henrydcase/pqc.git
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53 lines
1.3 KiB
C
53 lines
1.3 KiB
C
/**
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* WARNING
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*
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* This file generates a PREDICTABLE and NOT AT ALL RANDOM sequence of bytes.
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*
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* Its purpose is to support our testing suite and it MUST NOT be used in any
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* scenario where you are expecting actual cryptography to happen.
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*/
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#include <stdint.h>
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#include "randombytes.h"
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static uint32_t seed[32] = { 3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2,3,8,4,6,2,6,4,3,3,8,3,2,7,9,5 } ;
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static uint32_t in[12];
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static uint32_t out[8];
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static int32_t outleft = 0;
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#define ROTATE(x,b) (((x) << (b)) | ((x) >> (32 - (b))))
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#define MUSH(i,b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x,b));
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static void surf(void)
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{
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uint32_t t[12]; uint32_t x; uint32_t sum = 0;
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int32_t r; int32_t i; int32_t loop;
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for (i = 0;i < 12;++i) t[i] = in[i] ^ seed[12 + i];
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for (i = 0;i < 8;++i) out[i] = seed[24 + i];
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x = t[11];
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for (loop = 0;loop < 2;++loop) {
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for (r = 0;r < 16;++r) {
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sum += 0x9e3779b9;
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MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13)
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MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13)
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MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13)
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}
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for (i = 0;i < 8;++i) out[i] ^= t[i + 4];
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}
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}
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void randombytes(uint8_t *x,uint64_t xlen)
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{
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while (xlen > 0) {
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if (!outleft) {
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if (!++in[0]) if (!++in[1]) if (!++in[2]) ++in[3];
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surf();
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outleft = 8;
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}
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*x = out[--outleft];
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++x;
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--xlen;
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}
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}
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