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/*
* 20080913
* D. J. Bernstein
* Public domain.
* */
#include "crypto_hashblocks_sha256.h"
#include "crypto_auth.h"
#define blocks crypto_hashblocks_sha256
typedef unsigned int uint32;
static const char iv[32] = {
0x6a,0x09,0xe6,0x67,
0xbb,0x67,0xae,0x85,
0x3c,0x6e,0xf3,0x72,
0xa5,0x4f,0xf5,0x3a,
0x51,0x0e,0x52,0x7f,
0x9b,0x05,0x68,0x8c,
0x1f,0x83,0xd9,0xab,
0x5b,0xe0,0xcd,0x19,
} ;
int crypto_auth(unsigned char *out,const unsigned char *in,unsigned long long inlen,const unsigned char *k)
{
unsigned char h[32];
unsigned char padded[128];
int i;
unsigned long long bits = 512 + (inlen << 3);
for (i = 0;i < 32;++i) h[i] = iv[i];
for (i = 0;i < 32;++i) padded[i] = k[i] ^ 0x36;
for (i = 32;i < 64;++i) padded[i] = 0x36;
blocks(h,padded,64);
blocks(h,in,inlen);
in += inlen;
inlen &= 63;
in -= inlen;
for (i = 0;i < inlen;++i) padded[i] = in[i];
padded[inlen] = 0x80;
if (inlen < 56) {
for (i = inlen + 1;i < 56;++i) padded[i] = 0;
padded[56] = bits >> 56;
padded[57] = bits >> 48;
padded[58] = bits >> 40;
padded[59] = bits >> 32;
padded[60] = bits >> 24;
padded[61] = bits >> 16;
padded[62] = bits >> 8;
padded[63] = bits;
blocks(h,padded,64);
} else {
for (i = inlen + 1;i < 120;++i) padded[i] = 0;
padded[120] = bits >> 56;
padded[121] = bits >> 48;
padded[122] = bits >> 40;
padded[123] = bits >> 32;
padded[124] = bits >> 24;
padded[125] = bits >> 16;
padded[126] = bits >> 8;
padded[127] = bits;
blocks(h,padded,128);
}
for (i = 0;i < 32;++i) padded[i] = k[i] ^ 0x5c;
for (i = 32;i < 64;++i) padded[i] = 0x5c;
for (i = 0;i < 32;++i) padded[64 + i] = h[i];
for (i = 0;i < 32;++i) out[i] = iv[i];
for (i = 32;i < 64;++i) padded[64 + i] = 0;
padded[64 + 32] = 0x80;
padded[64 + 62] = 3;
blocks(out,padded,128);
return 0;
}
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