library/xtea.c

/*
 *  A 32-bit implementation of the XTEA algorithm
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#include "common.h"

#if defined(MBEDTLS_XTEA_C)

#include "mbedtls/xtea.h"
#include "mbedtls/platform_util.h"

#include <string.h>

#include "mbedtls/platform.h"

#if !defined(MBEDTLS_XTEA_ALT)

void mbedtls_xtea_init(mbedtls_xtea_context *ctx)
{
    memset(ctx, 0, sizeof(mbedtls_xtea_context));
}

void mbedtls_xtea_free(mbedtls_xtea_context *ctx)
{
    if (ctx == NULL) {
        return;
    }

    mbedtls_platform_zeroize(ctx, sizeof(mbedtls_xtea_context));
}

/*
 * XTEA key schedule
 */
void mbedtls_xtea_setup(mbedtls_xtea_context *ctx, const unsigned char key[16])
{
    int i;

    memset(ctx, 0, sizeof(mbedtls_xtea_context));

    for (i = 0; i < 4; i++) {
        ctx->k[i] = MBEDTLS_GET_UINT32_BE(key, i << 2);
    }
}

/*
 * XTEA encrypt function
 */
int mbedtls_xtea_crypt_ecb(mbedtls_xtea_context *ctx, int mode,
                           const unsigned char input[8], unsigned char output[8])
{
    uint32_t *k, v0, v1, i;

    k = ctx->k;

    v0 = MBEDTLS_GET_UINT32_BE(input, 0);
    v1 = MBEDTLS_GET_UINT32_BE(input, 4);

    if (mode == MBEDTLS_XTEA_ENCRYPT) {
        uint32_t sum = 0, delta = 0x9E3779B9;

        for (i = 0; i < 32; i++) {
            v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + k[sum & 3]);
            sum += delta;
            v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + k[(sum>>11) & 3]);
        }
    } else { /* MBEDTLS_XTEA_DECRYPT */
        uint32_t delta = 0x9E3779B9, sum = delta * 32;

        for (i = 0; i < 32; i++) {
            v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + k[(sum>>11) & 3]);
            sum -= delta;
            v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + k[sum & 3]);
        }
    }

    MBEDTLS_PUT_UINT32_BE(v0, output, 0);
    MBEDTLS_PUT_UINT32_BE(v1, output, 4);

    return 0;
}

#if defined(MBEDTLS_CIPHER_MODE_CBC)
/*
 * XTEA-CBC buffer encryption/decryption
 */
int mbedtls_xtea_crypt_cbc(mbedtls_xtea_context *ctx, int mode, size_t length,
                           unsigned char iv[8], const unsigned char *input,
                           unsigned char *output)
{
    int i;
    unsigned char temp[8];

    if (length % 8) {
        return MBEDTLS_ERR_XTEA_INVALID_INPUT_LENGTH;
    }

    if (mode == MBEDTLS_XTEA_DECRYPT) {
        while (length > 0) {
            memcpy(temp, input, 8);
            mbedtls_xtea_crypt_ecb(ctx, mode, input, output);

            for (i = 0; i < 8; i++) {
                output[i] = (unsigned char) (output[i] ^ iv[i]);
            }

            memcpy(iv, temp, 8);

            input  += 8;
            output += 8;
            length -= 8;
        }
    } else {
        while (length > 0) {
            for (i = 0; i < 8; i++) {
                output[i] = (unsigned char) (input[i] ^ iv[i]);
            }

            mbedtls_xtea_crypt_ecb(ctx, mode, output, output);
            memcpy(iv, output, 8);

            input  += 8;
            output += 8;
            length -= 8;
        }
    }

    return 0;
}
#endif /* MBEDTLS_CIPHER_MODE_CBC */
#endif /* !MBEDTLS_XTEA_ALT */

#if defined(MBEDTLS_SELF_TEST)

/*
 * XTEA tests vectors (non-official)
 */

static const unsigned char xtea_test_key[6][16] =
{
    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
      0x0c, 0x0d, 0x0e, 0x0f },
    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
      0x0c, 0x0d, 0x0e, 0x0f },
    { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
      0x0c, 0x0d, 0x0e, 0x0f },
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00 },
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00 },
    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
      0x00, 0x00, 0x00, 0x00 }
};

static const unsigned char xtea_test_pt[6][8] =
{
    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0x5a, 0x5b, 0x6e, 0x27, 0x89, 0x48, 0xd7, 0x7f },
    { 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0x70, 0xe1, 0x22, 0x5d, 0x6e, 0x4e, 0x76, 0x55 }
};

static const unsigned char xtea_test_ct[6][8] =
{
    { 0x49, 0x7d, 0xf3, 0xd0, 0x72, 0x61, 0x2c, 0xb5 },
    { 0xe7, 0x8f, 0x2d, 0x13, 0x74, 0x43, 0x41, 0xd8 },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 },
    { 0xa0, 0x39, 0x05, 0x89, 0xf8, 0xb8, 0xef, 0xa5 },
    { 0xed, 0x23, 0x37, 0x5a, 0x82, 0x1a, 0x8c, 0x2d },
    { 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41, 0x41 }
};

/*
 * Checkup routine
 */
int mbedtls_xtea_self_test(int verbose)
{
    int i, ret = 0;
    unsigned char buf[8];
    mbedtls_xtea_context ctx;

    mbedtls_xtea_init(&ctx);
    for (i = 0; i < 6; i++) {
        if (verbose != 0) {
            mbedtls_printf("  XTEA test #%d: ", i + 1);
        }

        memcpy(buf, xtea_test_pt[i], 8);

        mbedtls_xtea_setup(&ctx, xtea_test_key[i]);
        mbedtls_xtea_crypt_ecb(&ctx, MBEDTLS_XTEA_ENCRYPT, buf, buf);

        if (memcmp(buf, xtea_test_ct[i], 8) != 0) {
            if (verbose != 0) {
                mbedtls_printf("failed\n");
            }

            ret = 1;
            goto exit;
        }

        if (verbose != 0) {
            mbedtls_printf("passed\n");
        }
    }

    if (verbose != 0) {
        mbedtls_printf("\n");
    }

exit:
    mbedtls_xtea_free(&ctx);

    return ret;
}

#endif /* MBEDTLS_SELF_TEST */

#endif /* MBEDTLS_XTEA_C */