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  • /*
     * Copyright (C) 2012 Martin Storsjo
     *
     * This file is part of Libav.
     *
     * Libav is free software; you can redistribute it and/or
     * modify it under the terms of the GNU Lesser General Public
     * License as published by the Free Software Foundation; either
     * version 2.1 of the License, or (at your option) any later version.
     *
     * Libav is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     * Lesser General Public License for more details.
     *
     * You should have received a copy of the GNU Lesser General Public
     * License along with Libav; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
     */
    
    #include <string.h>
    
    
    #include "hmac.h"
    #include "md5.h"
    #include "sha.h"
    #include "mem.h"
    
    
    #define MAX_HASHLEN 32
    
    #define MAX_BLOCKLEN 64
    
    struct AVHMAC {
        void *hash;
        int blocklen, hashlen;
        void (*final)(void*, uint8_t*);
        void (*update)(void*, const uint8_t*, int len);
        void (*init)(void*);
        uint8_t key[MAX_BLOCKLEN];
        int keylen;
    };
    
    
    #define DEFINE_SHA(bits)                           \
    static av_cold void sha ## bits ##_init(void *ctx) \
    {                                                  \
        av_sha_init(ctx, bits);                        \
    
    DEFINE_SHA(160)
    DEFINE_SHA(224)
    DEFINE_SHA(256)
    
    
    AVHMAC *av_hmac_alloc(enum AVHMACType type)
    {
        AVHMAC *c = av_mallocz(sizeof(*c));
        if (!c)
            return NULL;
        switch (type) {
        case AV_HMAC_MD5:
            c->blocklen = 64;
            c->hashlen  = 16;
            c->init     = av_md5_init;
            c->update   = av_md5_update;
            c->final    = av_md5_final;
            c->hash     = av_md5_alloc();
            break;
        case AV_HMAC_SHA1:
            c->blocklen = 64;
            c->hashlen  = 20;
    
            c->init     = sha160_init;
            c->update   = av_sha_update;
            c->final    = av_sha_final;
            c->hash     = av_sha_alloc();
            break;
        case AV_HMAC_SHA224:
            c->blocklen = 64;
            c->hashlen  = 28;
            c->init     = sha224_init;
            c->update   = av_sha_update;
            c->final    = av_sha_final;
            c->hash     = av_sha_alloc();
            break;
        case AV_HMAC_SHA256:
            c->blocklen = 64;
            c->hashlen  = 32;
            c->init     = sha256_init;
    
            c->update   = av_sha_update;
            c->final    = av_sha_final;
            c->hash     = av_sha_alloc();
            break;
        default:
            av_free(c);
            return NULL;
        }
        if (!c->hash) {
            av_free(c);
            return NULL;
        }
        return c;
    }
    
    void av_hmac_free(AVHMAC *c)
    {
        if (!c)
            return;
        av_free(c->hash);
        av_free(c);
    }
    
    void av_hmac_init(AVHMAC *c, const uint8_t *key, unsigned int keylen)
    {
        int i;
        uint8_t block[MAX_BLOCKLEN];
        if (keylen > c->blocklen) {
            c->init(c->hash);
            c->update(c->hash, key, keylen);
            c->final(c->hash, c->key);
            c->keylen = c->hashlen;
        } else {
            memcpy(c->key, key, keylen);
            c->keylen = keylen;
        }
        c->init(c->hash);
        for (i = 0; i < c->keylen; i++)
            block[i] = c->key[i] ^ 0x36;
        for (i = c->keylen; i < c->blocklen; i++)
            block[i] = 0x36;
        c->update(c->hash, block, c->blocklen);
    }
    
    void av_hmac_update(AVHMAC *c, const uint8_t *data, unsigned int len)
    {
        c->update(c->hash, data, len);
    }
    
    int av_hmac_final(AVHMAC *c, uint8_t *out, unsigned int outlen)
    {
        uint8_t block[MAX_BLOCKLEN];
        int i;
        if (outlen < c->hashlen)
            return AVERROR(EINVAL);
        c->final(c->hash, out);
        c->init(c->hash);
        for (i = 0; i < c->keylen; i++)
            block[i] = c->key[i] ^ 0x5C;
        for (i = c->keylen; i < c->blocklen; i++)
            block[i] = 0x5C;
        c->update(c->hash, block, c->blocklen);
        c->update(c->hash, out, c->hashlen);
        c->final(c->hash, out);
        return c->hashlen;
    }
    
    int av_hmac_calc(AVHMAC *c, const uint8_t *data, unsigned int len,
                     const uint8_t *key, unsigned int keylen,
                     uint8_t *out, unsigned int outlen)
    {
        av_hmac_init(c, key, keylen);
        av_hmac_update(c, data, len);
        return av_hmac_final(c, out, outlen);
    }
    
    
    #ifdef TEST
    #include <stdio.h>
    
    static void test(AVHMAC *hmac, const uint8_t *key, int keylen,
                     const uint8_t *data, int datalen)
    {
        uint8_t buf[MAX_HASHLEN];
        int out, i;
        // Some of the test vectors are strings, where sizeof() includes the
        // trailing null byte - remove that.
        if (!key[keylen - 1])
            keylen--;
        if (!data[datalen - 1])
            datalen--;
        out = av_hmac_calc(hmac, data, datalen, key, keylen, buf, sizeof(buf));
        for (i = 0; i < out; i++)
            printf("%02x", buf[i]);
        printf("\n");
    }
    
    int main(void)
    {
    
        uint8_t key1[20], key3[131], data3[50];
        enum AVHMACType i = AV_HMAC_SHA224;
    
        const uint8_t key2[]  = "Jefe";
        const uint8_t data1[] = "Hi There";
        const uint8_t data2[] = "what do ya want for nothing?";
    
        const uint8_t data4[] = "Test Using Larger Than Block-Size Key - Hash Key First";
        const uint8_t data5[] = "Test Using Larger Than Block-Size Key and Larger Than One Block-Size Data";
        const uint8_t data6[] = "This is a test using a larger than block-size key and a larger "
                                "than block-size data. The key needs to be hashed before being used"
                                " by the HMAC algorithm.";
    
        AVHMAC *hmac = av_hmac_alloc(AV_HMAC_MD5);
        if (!hmac)
            return 1;
        memset(key1, 0x0b, sizeof(key1));
        memset(key3, 0xaa, sizeof(key3));
        memset(data3, 0xdd, sizeof(data3));
    
        // RFC 2202 test vectors
        test(hmac, key1, 16, data1, sizeof(data1));
        test(hmac, key2, sizeof(key2), data2, sizeof(data2));
        test(hmac, key3, 16, data3, sizeof(data3));
        test(hmac, key3, 80, data4, sizeof(data4));
        test(hmac, key3, 80, data5, sizeof(data5));
        av_hmac_free(hmac);
    
        /* SHA-1 */
        hmac = av_hmac_alloc(AV_HMAC_SHA1);
        if (!hmac)
            return 1;
        // RFC 2202 test vectors
    
        test(hmac, key1, sizeof(key1), data1, sizeof(data1));
        test(hmac, key2, sizeof(key2), data2, sizeof(data2));
    
        test(hmac, key3, 20, data3, sizeof(data3));
        test(hmac, key3, 80, data4, sizeof(data4));
        test(hmac, key3, 80, data5, sizeof(data5));
    
        av_hmac_free(hmac);
    
    
        /* SHA-2 */
        while (i <= AV_HMAC_SHA256) {
            hmac = av_hmac_alloc(i);
            // RFC 4231 test vectors
            test(hmac, key1, sizeof(key1), data1, sizeof(data1));
            test(hmac, key2, sizeof(key2), data2, sizeof(data2));
            test(hmac, key3, 20, data3, sizeof(data3));
            test(hmac, key3, sizeof(key3), data4, sizeof(data4));
            test(hmac, key3, sizeof(key3), data6, sizeof(data6));
            av_hmac_free(hmac);
            i++;
        }
    
        return 0;
    }
    #endif /* TEST */