关于数据加密问题（2）

关于数据加密问题

今天说下mbedtls中base64编解码
首先查看头文件

/**
 * \file base64.h
 *
 * \brief RFC 1521 base64 encoding/decoding
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  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.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */
#ifndef MBEDTLS_BASE64_H
#define MBEDTLS_BASE64_H

#include <stddef.h>

#define MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL               -0x002A  /**< Output buffer too small. */
#define MBEDTLS_ERR_BASE64_INVALID_CHARACTER              -0x002C  /**< Invalid character in input. */

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \brief          Encode a buffer into base64 format
 *
 * \param dst      destination buffer
 * \param dlen     size of the destination buffer
 * \param olen     number of bytes written
 * \param src      source buffer
 * \param slen     amount of data to be encoded
 *
 * \return         0 if successful, or MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL.
 *                 *olen is always updated to reflect the amount
 *                 of data that has (or would have) been written.
 *                 If that length cannot be represented, then no data is
 *                 written to the buffer and *olen is set to the maximum
 *                 length representable as a size_t.
 *
 * \note           Call this function with dlen = 0 to obtain the
 *                 required buffer size in *olen
 */
int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen,
                   const unsigned char *src, size_t slen );  //编码

/**
 * \brief          Decode a base64-formatted buffer
 *
 * \param dst      destination buffer (can be NULL for checking size)
 * \param dlen     size of the destination buffer
 * \param olen     number of bytes written
 * \param src      source buffer
 * \param slen     amount of data to be decoded
 *
 * \return         0 if successful, MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL, or
 *                 MBEDTLS_ERR_BASE64_INVALID_CHARACTER if the input data is
 *                 not correct. *olen is always updated to reflect the amount
 *                 of data that has (or would have) been written.
 *
 * \note           Call this function with *dst = NULL or dlen = 0 to obtain
 *                 the required buffer size in *olen
 */
int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
                   const unsigned char *src, size_t slen );//解码

/**
 * \brief          Checkup routine
 *
 * \return         0 if successful, or 1 if the test failed
 */
int mbedtls_base64_self_test( int verbose );

#ifdef __cplusplus
}
#endif

#endif /* base64.h */

测试程序

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<mbedtls/base64.h>

int main(int argc, const char *argv[])
{
        unsigned char date[64] = "hello world,i come from china";
        unsigned char enbasestring[64];
        unsigned char debasestring[64];
        size_t len;
        printf("date:%s\n",date);

        mbedtls_base64_encode(enbasestring,64,&len,date,strlen(date));

        printf("base64:%s,len:%d\n",enbasestring,(int)len);

        mbedtls_base64_decode(debasestring,64,&len,enbasestring,strlen(enbasestring));
        printf("encode string:%s,len:%d\n",debasestring,(int)len);

        return 0;
}

编译如果关于数据加密问题（1）能够编译成功，这个可以直接编译运行了，不过不行，请先按关于数据加密问题（1）操作
编译

gcc base64_test.c -o base64_test -L/usr/local/lib -lmbedcrypto

运行

上文是对hello world,i come from china字符串进行base64编解码，现在使用在线base64编解码做下对比

在线工具链接：点击这里

对比发现，编码结果是一致的。