196 lines
5.0 KiB
C
196 lines
5.0 KiB
C
#include "os.h"
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#include <libsec.h>
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/*
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poly1305 implementation using 32 bit * 32 bit = 64 bit multiplication and 64 bit addition
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derived from http://github.com/floodberry/poly1305-donna
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*/
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#define U8TO32(p) ((uint32_t)(p)[0] | (uint32_t)(p)[1]<<8 | (uint32_t)(p)[2]<<16 | (uint32_t)(p)[3]<<24)
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#define U32TO8(p, v) (p)[0]=(v), (p)[1]=(v)>>8, (p)[2]=(v)>>16, (p)[3]=(v)>>24
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/* (r,s) = (key[0:15],key[16:31]), the one time key */
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DigestState*
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poly1305(uint8_t *m, uint32_t len, uint8_t *key, uint32_t klen, uint8_t *digest, DigestState *s)
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{
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uint32_t r0,r1,r2,r3,r4, s1,s2,s3,s4, h0,h1,h2,h3,h4, g0,g1,g2,g3,g4;
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uint64_t d0,d1,d2,d3,d4, f;
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uint32_t hibit, mask, c;
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if(s == nil){
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s = jehanne_malloc(sizeof(*s));
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if(s == nil)
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return nil;
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jehanne_memset(s, 0, sizeof(*s));
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s->malloced = 1;
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}
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if(s->seeded == 0){
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assert(klen == 32);
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/* r &= 0xffffffc0ffffffc0ffffffc0fffffff */
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s->state[0] = (U8TO32(&key[ 0]) ) & 0x3ffffff;
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s->state[1] = (U8TO32(&key[ 3]) >> 2) & 0x3ffff03;
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s->state[2] = (U8TO32(&key[ 6]) >> 4) & 0x3ffc0ff;
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s->state[3] = (U8TO32(&key[ 9]) >> 6) & 0x3f03fff;
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s->state[4] = (U8TO32(&key[12]) >> 8) & 0x00fffff;
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/* h = 0 */
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s->state[5] = 0;
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s->state[6] = 0;
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s->state[7] = 0;
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s->state[8] = 0;
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s->state[9] = 0;
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/* save pad for later */
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s->state[10] = U8TO32(&key[16]);
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s->state[11] = U8TO32(&key[20]);
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s->state[12] = U8TO32(&key[24]);
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s->state[13] = U8TO32(&key[28]);
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s->seeded = 1;
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}
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if(s->blen){
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c = 16 - s->blen;
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if(c > len)
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c = len;
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jehanne_memmove(s->buf + s->blen, m, c);
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len -= c, m += c;
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s->blen += c;
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if(s->blen == 16){
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s->blen = 0;
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poly1305(s->buf, 16, key, klen, nil, s);
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} else if(len == 0){
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m = s->buf;
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len = s->blen;
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s->blen = 0;
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}
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}
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r0 = s->state[0];
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r1 = s->state[1];
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r2 = s->state[2];
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r3 = s->state[3];
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r4 = s->state[4];
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h0 = s->state[5];
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h1 = s->state[6];
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h2 = s->state[7];
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h3 = s->state[8];
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h4 = s->state[9];
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s1 = r1 * 5;
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s2 = r2 * 5;
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s3 = r3 * 5;
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s4 = r4 * 5;
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hibit = 1<<24; /* 1<<128 */
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while(len >= 16){
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Block:
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/* h += m[i] */
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h0 += (U8TO32(&m[0]) ) & 0x3ffffff;
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h1 += (U8TO32(&m[3]) >> 2) & 0x3ffffff;
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h2 += (U8TO32(&m[6]) >> 4) & 0x3ffffff;
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h3 += (U8TO32(&m[9]) >> 6) & 0x3ffffff;
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h4 += (U8TO32(&m[12])>> 8) | hibit;
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/* h *= r */
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d0 = ((uint64_t)h0 * r0) + ((uint64_t)h1 * s4) + ((uint64_t)h2 * s3) + ((uint64_t)h3 * s2) + ((uint64_t)h4 * s1);
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d1 = ((uint64_t)h0 * r1) + ((uint64_t)h1 * r0) + ((uint64_t)h2 * s4) + ((uint64_t)h3 * s3) + ((uint64_t)h4 * s2);
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d2 = ((uint64_t)h0 * r2) + ((uint64_t)h1 * r1) + ((uint64_t)h2 * r0) + ((uint64_t)h3 * s4) + ((uint64_t)h4 * s3);
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d3 = ((uint64_t)h0 * r3) + ((uint64_t)h1 * r2) + ((uint64_t)h2 * r1) + ((uint64_t)h3 * r0) + ((uint64_t)h4 * s4);
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d4 = ((uint64_t)h0 * r4) + ((uint64_t)h1 * r3) + ((uint64_t)h2 * r2) + ((uint64_t)h3 * r1) + ((uint64_t)h4 * r0);
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/* (partial) h %= p */
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c = (uint32_t)(d0 >> 26); h0 = (uint32_t)d0 & 0x3ffffff;
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d1 += c; c = (uint32_t)(d1 >> 26); h1 = (uint32_t)d1 & 0x3ffffff;
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d2 += c; c = (uint32_t)(d2 >> 26); h2 = (uint32_t)d2 & 0x3ffffff;
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d3 += c; c = (uint32_t)(d3 >> 26); h3 = (uint32_t)d3 & 0x3ffffff;
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d4 += c; c = (uint32_t)(d4 >> 26); h4 = (uint32_t)d4 & 0x3ffffff;
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h0 += c * 5; c = (h0 >> 26); h0 = h0 & 0x3ffffff;
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h1 += c;
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len -= 16, m += 16;
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}
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if(len){
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s->blen = len;
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jehanne_memmove(s->buf, m, len);
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}
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if(digest == nil){
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s->state[5] = h0;
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s->state[6] = h1;
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s->state[7] = h2;
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s->state[8] = h3;
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s->state[9] = h4;
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return s;
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}
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if(len){
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m = s->buf;
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m[len++] = 1;
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while(len < 16)
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m[len++] = 0;
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hibit = 0;
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goto Block;
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}
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c = h1 >> 26; h1 = h1 & 0x3ffffff;
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h2 += c; c = h2 >> 26; h2 = h2 & 0x3ffffff;
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h3 += c; c = h3 >> 26; h3 = h3 & 0x3ffffff;
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h4 += c; c = h4 >> 26; h4 = h4 & 0x3ffffff;
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h0 += c * 5; c = h0 >> 26; h0 = h0 & 0x3ffffff;
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h1 += c;
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/* compute h + -p */
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g0 = h0 + 5; c = g0 >> 26; g0 &= 0x3ffffff;
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g1 = h1 + c; c = g1 >> 26; g1 &= 0x3ffffff;
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g2 = h2 + c; c = g2 >> 26; g2 &= 0x3ffffff;
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g3 = h3 + c; c = g3 >> 26; g3 &= 0x3ffffff;
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g4 = h4 + c - (1 << 26);
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/* select h if h < p, or h + -p if h >= p */
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mask = (g4 >> 31) - 1;
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g0 &= mask;
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g1 &= mask;
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g2 &= mask;
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g3 &= mask;
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g4 &= mask;
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mask = ~mask;
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h0 = (h0 & mask) | g0;
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h1 = (h1 & mask) | g1;
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h2 = (h2 & mask) | g2;
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h3 = (h3 & mask) | g3;
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h4 = (h4 & mask) | g4;
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/* h = h % (2^128) */
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h0 = (h0 ) | (h1 << 26);
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h1 = (h1 >> 6) | (h2 << 20);
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h2 = (h2 >> 12) | (h3 << 14);
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h3 = (h3 >> 18) | (h4 << 8);
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/* digest = (h + pad) % (2^128) */
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f = (uint64_t)h0 + s->state[10] ; h0 = (uint32_t)f;
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f = (uint64_t)h1 + s->state[11] + (f >> 32); h1 = (uint32_t)f;
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f = (uint64_t)h2 + s->state[12] + (f >> 32); h2 = (uint32_t)f;
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f = (uint64_t)h3 + s->state[13] + (f >> 32); h3 = (uint32_t)f;
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U32TO8(&digest[0], h0);
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U32TO8(&digest[4], h1);
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U32TO8(&digest[8], h2);
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U32TO8(&digest[12], h3);
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if(s->malloced){
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jehanne_memset(s, 0, sizeof(*s));
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jehanne_free(s);
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return nil;
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}
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jehanne_memset(s, 0, sizeof(*s));
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return nil;
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}
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