BASE64编码and解码的C实现

来源：互联网发布：诵读古兰经软件编辑：程序博客网时间：2024/04/29 02:14
#include "stdio.h"#include "string.h"static char base64_encode_map[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; static int base64_decode_map[256] = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, };/* ZhangYaMin * #base64 编码 * @param sInput 输入字符串 * @param iLen 输入字符串长度 * @param sOutput 输出字符串 */int base64_encode(const unsigned char *sInput, const int iLen, unsigned char *sOutput){if (sInput == NULL || sOutput==NULL || iLen <= 0) return -1;//保证逻辑右移unsigned char *p = (unsigned char *)sInput;unsigned char *pOut = sOutput;unsigned char *pEnd = (unsigned char *)sInput + iLen;while (pEnd - p >= 3) {*pOut++ = base64_encode_map[( p[0] >> 2 )];*pOut++ = base64_encode_map[( (p[0] << 4) & 0x30 ) | ( p[1] >> 4 )];*pOut++ = base64_encode_map[( (p[1] << 2) & 0x3C ) | ( p[2] >> 6 )];*pOut++ = base64_encode_map[p[2] & 0x3F];p += 3;}if (pEnd - p > 0) {*pOut++ = base64_encode_map[(p[0] >> 2)];if (pEnd - p == 2) {*pOut++ = base64_encode_map[( (p[0] << 4) & 0x30 ) | ( p[1] >> 4 )];*pOut++ = base64_encode_map[(p[1] << 2) & 0x3C]; *pOut++ = '=';} else if (pEnd - p == 1) {*pOut++ = base64_encode_map[(p[1] << 4) & 0x30];*pOut++ = '=';*pOut++ = '=';}}return 0;}/* ZhangYaMin * #base64 解码 * @param sInput 输入base64字符串 * @param sOutput 输出字符串 */int base64_decode(const unsigned char* sInput,unsigned char *sOutput){if (sInput == NULL || sOutput == NULL) return -1;int iInputLen = strlen(sInput);if (iInputLen < 4 || iInputLen % 4 != 0) return -1;//保证逻辑右移unsigned char *p = (unsigned char*)sInput;unsigned char *pOut = sOutput;unsigned char *pEnd = (unsigned char*)sInput + iInputLen;for (; p < pEnd; p += 4) {*pOut++ = ((base64_decode_map[p[0]] << 2) & 0xFC) | ((base64_decode_map[p[1]] >> 4) & 0x03);*pOut++ = ((base64_decode_map[p[1]] << 4) & 0xF0) | ((base64_decode_map[p[2]] >> 2) & 0x0F);*pOut++ = ((base64_decode_map[p[2]] << 6) & 0xC0) | (base64_decode_map[p[3]]); }if (*(sInput + iInputLen - 2) == '=') {*(pOut - 2) = '\0';} else if (*(sInput + iInputLen - 1) == '=') {*(pOut - 1) = '\0';}return 0;}
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