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/*
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 * Copyright (C) 2007 Michael Niedermayer <michaelni@gmx.at>
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 * based on public domain SHA-1 code by Steve Reid <steve@edmweb.com>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "common.h"
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#include "bswap.h"
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#include "sha1.h"
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/** hash context */
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typedef struct AVSHA1 {
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    uint8_t  digest_len;  ///< digest length in 32-bit words
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    uint64_t count;       ///< number of bytes in buffer
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    uint8_t  buffer[64];  ///< 512-bit buffer of input values used in hash updating
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    uint32_t state[8];    ///< current hash value
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    /** function used to update hash for 512-bit input block */
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    void     (*transform)(uint32_t *state, const uint8_t buffer[64]);
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} AVSHA1;
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const int av_sha1_size = sizeof(AVSHA1);
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#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))
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/* (R0+R1), R2, R3, R4 are the different operations used in SHA1 */
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#define blk0(i) (block[i] = be2me_32(((const uint32_t*)buffer)[i]))
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#define blk(i)  (block[i] = rol(block[i-3] ^ block[i-8] ^ block[i-14] ^ block[i-16], 1))
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#define R0(v,w,x,y,z,i) z += ((w&(x^y))^y)     + blk0(i) + 0x5A827999 + rol(v, 5); w = rol(w, 30);
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#define R1(v,w,x,y,z,i) z += ((w&(x^y))^y)     + blk (i) + 0x5A827999 + rol(v, 5); w = rol(w, 30);
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#define R2(v,w,x,y,z,i) z += ( w^x     ^y)     + blk (i) + 0x6ED9EBA1 + rol(v, 5); w = rol(w, 30);
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#define R3(v,w,x,y,z,i) z += (((w|x)&y)|(w&x)) + blk (i) + 0x8F1BBCDC + rol(v, 5); w = rol(w, 30);
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#define R4(v,w,x,y,z,i) z += ( w^x     ^y)     + blk (i) + 0xCA62C1D6 + rol(v, 5); w = rol(w, 30);
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/* Hash a single 512-bit block. This is the core of the algorithm. */
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static void sha1_transform(uint32_t state[5], const uint8_t buffer[64])
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{
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    uint32_t block[80];
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    unsigned int i, a, b, c, d, e;
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    a = state[0];
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    b = state[1];
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    c = state[2];
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    d = state[3];
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    e = state[4];
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#if CONFIG_SMALL
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    for (i = 0; i < 80; i++) {
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        int t;
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        if (i < 16)
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            t = be2me_32(((uint32_t*)buffer)[i]);
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        else
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            t = rol(block[i-3] ^ block[i-8] ^ block[i-14] ^ block[i-16], 1);
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        block[i] = t;
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        t += e + rol(a, 5);
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        if (i < 40) {
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            if (i < 20)
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                t += ((b&(c^d))^d)     + 0x5A827999;
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            else
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                t += ( b^c     ^d)     + 0x6ED9EBA1;
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        } else {
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            if (i < 60)
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                t += (((b|c)&d)|(b&c)) + 0x8F1BBCDC;
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            else
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                t += ( b^c     ^d)     + 0xCA62C1D6;
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        }
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        e = d;
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        d = c;
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        c = rol(b, 30);
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        b = a;
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        a = t;
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    }
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#else
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    for (i = 0; i < 15; i += 5) {
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        R0(a, b, c, d, e, 0 + i);
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        R0(e, a, b, c, d, 1 + i);
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        R0(d, e, a, b, c, 2 + i);
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        R0(c, d, e, a, b, 3 + i);
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        R0(b, c, d, e, a, 4 + i);
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    }
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    R0(a, b, c, d, e, 15);
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    R1(e, a, b, c, d, 16);
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    R1(d, e, a, b, c, 17);
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    R1(c, d, e, a, b, 18);
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    R1(b, c, d, e, a, 19);
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    for (i = 20; i < 40; i += 5) {
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        R2(a, b, c, d, e, 0 + i);
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        R2(e, a, b, c, d, 1 + i);
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        R2(d, e, a, b, c, 2 + i);
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        R2(c, d, e, a, b, 3 + i);
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        R2(b, c, d, e, a, 4 + i);
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    }
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    for (; i < 60; i += 5) {
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        R3(a, b, c, d, e, 0 + i);
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        R3(e, a, b, c, d, 1 + i);
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        R3(d, e, a, b, c, 2 + i);
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        R3(c, d, e, a, b, 3 + i);
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        R3(b, c, d, e, a, 4 + i);
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    }
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    for (; i < 80; i += 5) {
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        R4(a, b, c, d, e, 0 + i);
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        R4(e, a, b, c, d, 1 + i);
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        R4(d, e, a, b, c, 2 + i);
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        R4(c, d, e, a, b, 3 + i);
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        R4(b, c, d, e, a, 4 + i);
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    }
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#endif
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    state[0] += a;
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    state[1] += b;
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    state[2] += c;
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    state[3] += d;
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    state[4] += e;
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}
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void av_sha1_init(AVSHA1* ctx)
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{
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    ctx->state[0] = 0x67452301;
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    ctx->state[1] = 0xEFCDAB89;
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    ctx->state[2] = 0x98BADCFE;
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    ctx->state[3] = 0x10325476;
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    ctx->state[4] = 0xC3D2E1F0;
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    ctx->transform = sha1_transform;
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    ctx->count    = 0;
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}
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void av_sha1_update(AVSHA1* ctx, const uint8_t* data, unsigned int len)
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{
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    unsigned int i, j;
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    j = ctx->count & 63;
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    ctx->count += len;
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#if CONFIG_SMALL
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    for (i = 0; i < len; i++) {
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        ctx->buffer[j++] = data[i];
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        if (64 == j) {
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            ctx->transform(ctx->state, ctx->buffer);
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            j = 0;
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        }
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    }
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#else
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    if ((j + len) > 63) {
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        memcpy(&ctx->buffer[j], data, (i = 64 - j));
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        ctx->transform(ctx->state, ctx->buffer);
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        for (; i + 63 < len; i += 64)
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            ctx->transform(ctx->state, &data[i]);
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        j = 0;
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    } else
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        i = 0;
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    memcpy(&ctx->buffer[j], &data[i], len - i);
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#endif
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}
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void av_sha1_final(AVSHA1* ctx, uint8_t digest[20])
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{
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    int i;
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    uint64_t finalcount = be2me_64(ctx->count << 3);
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    av_sha1_update(ctx, "\200", 1);
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    while ((ctx->count & 63) != 56)
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        av_sha1_update(ctx, "", 1);
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    av_sha1_update(ctx, (uint8_t *)&finalcount, 8); /* Should cause a transform() */
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    for (i = 0; i < 5; i++)
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        ((uint32_t*)digest)[i] = be2me_32(ctx->state[i]);
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}
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#ifdef TEST
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#include <stdio.h>
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#undef printf
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int main(void)
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{
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    int i, k;
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    AVSHA1 ctx;
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    unsigned char digest[20];
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    for (k = 0; k < 3; k++) {
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        av_sha1_init(&ctx);
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        if (k == 0)
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            av_sha1_update(&ctx, "abc", 3);
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        else if (k == 1)
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            av_sha1_update(&ctx, "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", 56);
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        else
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            for (i = 0; i < 1000 * 1000; i++)
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                av_sha1_update(&ctx, "a", 1);
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        av_sha1_final(&ctx, digest);
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        for (i = 0; i < 20; i++)
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            printf("%02X", digest[i]);
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        putchar('\n');
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    }
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    //test vectors (from FIPS PUB 180-1)
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    printf("A9993E36 4706816A BA3E2571 7850C26C 9CD0D89D\n"
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           "84983E44 1C3BD26E BAAE4AA1 F95129E5 E54670F1\n"
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           "34AA973C D4C4DAA4 F61EEB2B DBAD2731 6534016F\n");
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    return 0;
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}
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#endif