/*

 * Copyright 2011-2025 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

/*

 * MD5 and RC4 low level APIs are deprecated for public use, but still ok for

 * internal use.

 */

#include "internal/deprecated.h"

#include "internal/cryptlib.h"

#include <openssl/opensslconf.h>

#include <stdio.h>

#include <string.h>

#if !defined(OPENSSL_NO_RC4) && !defined(OPENSSL_NO_MD5)

#include <openssl/crypto.h>

#include <openssl/evp.h>

#include <openssl/objects.h>

#include <openssl/rc4.h>

#include <openssl/md5.h>

#include "crypto/evp.h"

typedef struct {

    RC4_KEY ks;

    MD5_CTX head, tail, md;

    size_t payload_length;

} EVP_RC4_HMAC_MD5;

#define NO_PAYLOAD_LENGTH ((size_t)-1)

void rc4_md5_enc(RC4_KEY *key, const void *in0, void *out,

    MD5_CTX *ctx, const void *inp, size_t blocks);

#define data(ctx) ((EVP_RC4_HMAC_MD5 *)EVP_CIPHER_CTX_get_cipher_data(ctx))

static int rc4_hmac_md5_init_key(EVP_CIPHER_CTX *ctx,

    const unsigned char *inkey,

    const unsigned char *iv, int enc)

{

    EVP_RC4_HMAC_MD5 *key = data(ctx);

    const int keylen = EVP_CIPHER_CTX_get_key_length(ctx);

    if (keylen <= 0)

        return 0;

    RC4_set_key(&key->ks, keylen, inkey);

    MD5_Init(&key->head); /* handy when benchmarking */

    key->tail = key->head;

    key->md = key->head;

    key->payload_length = NO_PAYLOAD_LENGTH;

    return 1;

}

#if defined(RC4_ASM) && defined(MD5_ASM) && (defined(__x86_64) || defined(__x86_64__) || defined(_M_AMD64) || defined(_M_X64))

#define STITCHED_CALL

#endif

#if !defined(STITCHED_CALL)

#define rc4_off 0

#define md5_off 0

#endif

static int rc4_hmac_md5_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,

    const unsigned char *in, size_t len)

{

    EVP_RC4_HMAC_MD5 *key = data(ctx);

#if defined(STITCHED_CALL)

    size_t rc4_off = 32 - 1 - (key->ks.x & (32 - 1)), /* 32 is $MOD from

                                                       * rc4_md5-x86_64.pl */

        md5_off = MD5_CBLOCK - key->md.num, blocks;

    unsigned int l;

#endif

    size_t plen = key->payload_length;

    if (plen != NO_PAYLOAD_LENGTH && len != (plen + MD5_DIGEST_LENGTH))

        return 0;

    if (EVP_CIPHER_CTX_is_encrypting(ctx)) {

        if (plen == NO_PAYLOAD_LENGTH)

            plen = len;

#if defined(STITCHED_CALL)

        /* cipher has to "fall behind" */

        if (rc4_off > md5_off)

            md5_off += MD5_CBLOCK;

        if (plen > md5_off && (blocks = (plen - md5_off) / MD5_CBLOCK) && (OPENSSL_ia32cap_P[0] & (1 << 20)) == 0) {

            MD5_Update(&key->md, in, md5_off);

            RC4(&key->ks, rc4_off, in, out);

            rc4_md5_enc(&key->ks, in + rc4_off, out + rc4_off,

                &key->md, in + md5_off, blocks);

            blocks *= MD5_CBLOCK;

            rc4_off += blocks;

            md5_off += blocks;

            key->md.Nh += (unsigned int)(blocks >> 29);

            key->md.Nl += (unsigned int)(blocks <<= 3);

            if (key->md.Nl < (unsigned int)blocks)

                key->md.Nh++;

        } else {

            rc4_off = 0;

            md5_off = 0;

        }

#endif

        MD5_Update(&key->md, in + md5_off, plen - md5_off);

        if (plen != len) { /* "TLS" mode of operation */

            if (in != out)

                memcpy(out + rc4_off, in + rc4_off, plen - rc4_off);

            /* calculate HMAC and append it to payload */

            MD5_Final(out + plen, &key->md);

            key->md = key->tail;

            MD5_Update(&key->md, out + plen, MD5_DIGEST_LENGTH);

            MD5_Final(out + plen, &key->md);

            /* encrypt HMAC at once */

            RC4(&key->ks, len - rc4_off, out + rc4_off, out + rc4_off);

        } else {

            RC4(&key->ks, len - rc4_off, in + rc4_off, out + rc4_off);

        }

    } else {

        unsigned char mac[MD5_DIGEST_LENGTH];

#if defined(STITCHED_CALL)

        /* digest has to "fall behind" */

        if (md5_off > rc4_off)

            rc4_off += 2 * MD5_CBLOCK;

        else

            rc4_off += MD5_CBLOCK;

        if (len > rc4_off && (blocks = (len - rc4_off) / MD5_CBLOCK) && (OPENSSL_ia32cap_P[0] & (1 << 20)) == 0) {

            RC4(&key->ks, rc4_off, in, out);

            MD5_Update(&key->md, out, md5_off);

            rc4_md5_enc(&key->ks, in + rc4_off, out + rc4_off,

                &key->md, out + md5_off, blocks);

            blocks *= MD5_CBLOCK;

            rc4_off += blocks;

            md5_off += blocks;

            l = (key->md.Nl + (blocks << 3)) & 0xffffffffU;

            if (l < key->md.Nl)

                key->md.Nh++;

            key->md.Nl = l;

            key->md.Nh += (unsigned int)(blocks >> 29);

        } else {

            md5_off = 0;

            rc4_off = 0;

        }

#endif

        /* decrypt HMAC at once */

        RC4(&key->ks, len - rc4_off, in + rc4_off, out + rc4_off);

        if (plen != NO_PAYLOAD_LENGTH) { /* "TLS" mode of operation */

            MD5_Update(&key->md, out + md5_off, plen - md5_off);

            /* calculate HMAC and verify it */

            MD5_Final(mac, &key->md);

            key->md = key->tail;

            MD5_Update(&key->md, mac, MD5_DIGEST_LENGTH);

            MD5_Final(mac, &key->md);

            if (CRYPTO_memcmp(out + plen, mac, MD5_DIGEST_LENGTH))

                return 0;

        } else {

            MD5_Update(&key->md, out + md5_off, len - md5_off);

        }

    }

    key->payload_length = NO_PAYLOAD_LENGTH;

    return 1;

}

static int rc4_hmac_md5_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg,

    void *ptr)

{

    EVP_RC4_HMAC_MD5 *key = data(ctx);

    switch (type) {

    case EVP_CTRL_AEAD_SET_MAC_KEY: {

        unsigned int i;

        unsigned char hmac_key[64];

        memset(hmac_key, 0, sizeof(hmac_key));

        if (arg > (int)sizeof(hmac_key)) {

            MD5_Init(&key->head);

            MD5_Update(&key->head, ptr, arg);

            MD5_Final(hmac_key, &key->head);

        } else {

            memcpy(hmac_key, ptr, arg);

        }

        for (i = 0; i < sizeof(hmac_key); i++)

            hmac_key[i] ^= 0x36; /* ipad */

        MD5_Init(&key->head);

        MD5_Update(&key->head, hmac_key, sizeof(hmac_key));

        for (i = 0; i < sizeof(hmac_key); i++)

            hmac_key[i] ^= 0x36 ^ 0x5c; /* opad */

        MD5_Init(&key->tail);

        MD5_Update(&key->tail, hmac_key, sizeof(hmac_key));

        OPENSSL_cleanse(hmac_key, sizeof(hmac_key));

        return 1;

    }

    case EVP_CTRL_AEAD_TLS1_AAD: {

        unsigned char *p = ptr;

        unsigned int len;

        if (arg != EVP_AEAD_TLS1_AAD_LEN)

            return -1;

        len = p[arg - 2] << 8 | p[arg - 1];

        if (!EVP_CIPHER_CTX_is_encrypting(ctx)) {

            if (len < MD5_DIGEST_LENGTH)

                return -1;

            len -= MD5_DIGEST_LENGTH;

            p[arg - 2] = len >> 8;

            p[arg - 1] = len;

        }

        key->payload_length = len;

        key->md = key->head;

        MD5_Update(&key->md, p, arg);

        return MD5_DIGEST_LENGTH;

    }

    default:

        return -1;

    }

}

static const EVP_CIPHER r4_hmac_md5_cipher = {

#ifdef NID_rc4_hmac_md5

    NID_rc4_hmac_md5,

#else

    NID_undef,

#endif

    1, EVP_RC4_KEY_SIZE, 0,

    EVP_CIPH_STREAM_CIPHER | EVP_CIPH_VARIABLE_LENGTH | EVP_CIPH_FLAG_AEAD_CIPHER,

    EVP_ORIG_GLOBAL,

    rc4_hmac_md5_init_key,

    rc4_hmac_md5_cipher,

    NULL,

    sizeof(EVP_RC4_HMAC_MD5),

    NULL,

    NULL,

    rc4_hmac_md5_ctrl,

    NULL

};

const EVP_CIPHER *EVP_rc4_hmac_md5(void)

{

    return &r4_hmac_md5_cipher;

}

#endif