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base64编码(c语言实现)
Base64-维基百科
在线加密解密工具
#include <stdio.h> #include <stdint.h> #include <string.h> #include <malloc.h> char base64_table[] = { ‘A‘,‘B‘,‘C‘,‘D‘,‘E‘,‘F‘,‘G‘,‘H‘,‘I‘,‘J‘, ‘K‘,‘L‘,‘M‘,‘N‘,‘O‘,‘P‘,‘Q‘,‘R‘,‘S‘,‘T‘, ‘U‘,‘V‘,‘W‘,‘X‘,‘Y‘,‘Z‘,‘a‘,‘b‘,‘c‘,‘d‘, ‘e‘,‘f‘,‘g‘,‘h‘,‘i‘,‘j‘,‘k‘,‘l‘,‘m‘,‘n‘, ‘o‘,‘p‘,‘q‘,‘r‘,‘s‘,‘t‘,‘u‘,‘v‘,‘w‘,‘x‘, ‘y‘,‘z‘,‘0‘,‘1‘,‘2‘,‘3‘,‘4‘,‘5‘,‘6‘,‘7‘, ‘8‘,‘9‘,‘+‘, ‘-‘, ‘\0‘ }; void base64_map(uint8_t *in_block, int len) { for(int i = 0; i < len; ++i) { in_block[i] = base64_table[in_block[i]]; //printf("%d %c",in_block[i], base64_table[in_block[i]]); } if(len % 4 == 3) in_block[len] = ‘=‘; else if(len % 4 == 2) in_block[len] = in_block[len+1] = ‘=‘; return ; } void base64_unmap(char *in_block) { int i; char *c; for(int i = 0; i < 4; ++i) { c = in_block + i; if(*c>=‘A‘ && *c<=‘Z‘) { *c -= ‘A‘; continue; } if(*c>=‘a‘ && *c<=‘z‘) { *c -= ‘a‘; *c += 26; continue; } if(*c == ‘+‘) { *c = 62; continue; } if(*c == ‘/‘) { *c = 63; continue; } if(*c == ‘=‘) { *c = 0; continue; } *c -= ‘0‘; *c += 52; } } int base64_encode(char *in, int inlen, uint8_t *out) { char *in_block; uint8_t *out_block; char temp[3]; out_block = out; in_block = in; for(int i = 0; i < inlen; i += 3) { memset(temp, 0, 3); memcpy(temp, in_block, i + 3 < inlen ? 3 : inlen - i); memset(out_block, 0, 4); out_block[0] = (temp[0] >> 2) & 0x3f; out_block[1] = ((temp[0] << 4) & 0x30) | ((temp[1] >> 4) & 0x0f); out_block[2] = ((temp[1] << 2) & 0x3c) | ((temp[2] >> 6) & 0x03); out_block[3] = (temp[2]) & 0x3f; //printf("%.2x %.2x %.2x\n", temp[0], temp[1], temp[2]); //printf("%.2x %.2x %.2x %.2x\n", out_block[0], out_block[1], out_block[2], out_block[3]); out_block += 4; in_block += 3; } base64_map(out, ((inlen * 4) - 1) / 3 + 1); } int base64_decode(char *in, int inlen, uint8_t *out) { char *in_block; uint8_t *out_block; char temp[4]; out_block = out; in_block = in; for(int i = 0; i < inlen; i += 4) { if(*in_block == ‘=‘) return 0; memcpy(temp, in_block, 4); memset(out_block, 0, 3); base64_unmap(temp); out_block[0] = ((temp[0]<<2) & 0xfc) | ((temp[1]>>4) & 3); out_block[1] = ((temp[1]<<4) & 0xf0) | ((temp[2]>>2) & 0xf); out_block[2] = ((temp[2]<<6) & 0xc0) | ((temp[3] ) & 0x3f); out_block += 3; in_block +=4; } return 0; } int main() { char cipher_text[64]; while(scanf("%s", cipher_text) != EOF) { printf("%s\n", cipher_text); uint8_t *tran_cipher = (uint8_t *)malloc(sizeof(uint8_t) * 64); memset(tran_cipher, 0, sizeof(uint8_t) * 64); #define ENCODE #define DECODE #ifdef ENCODE printf("----------------ENCODE-----------------"); base64_encode(cipher_text, strlen(cipher_text), tran_cipher); int len = (strlen(cipher_text) * 4 - 1) / 3 + 1; len = len % 4 == 3 ? len + 1 : len + 2; for(int i = 0; i < len ; ++i) printf("%c", tran_cipher[i]); printf("\n"); #endif // ENCODE #ifdef DECODE printf("----------------DECODE-----------------"); base64_decode(cipher_text, strlen(cipher_text), tran_cipher); len = strlen(cipher_text); int n = len; while(cipher_text[--n] == ‘=‘) ; if(n == len-2) len = (len >> 2) * 3 - 1; else if(n == len-3) len = (len >> 2) * 3 - 2; else if(n == len-1) len = (len >> 2) * 3; for(int i = 0; i < len; ++i) printf("%c", tran_cipher[i]); printf("\n"); #endif // DECODE } return 0; }
base64编码(c语言实现)
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