使用openssl库EVP编程计算md5值

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参考openssl中的md5test.c

#include <stdio.h>#include <string.h>#include <stdlib.h>#include <openssl/evp.h>#include <openssl/md5.h>#include <openssl/err.h>static char *test[] = {"","a","abc","message digest","abcdefghijklmnopqrstuvwxyz","ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789","12345678901234567890123456789012345678901234567890123456789012345678901234567890",NULL,};static char *ret[] = {"d41d8cd98f00b204e9800998ecf8427e","0cc175b9c0f1b6a831c399e269772661","900150983cd24fb0d6963f7d28e17f72","f96b697d7cb7938d525a2f31aaf161d0","c3fcd3d76192e4007dfb496cca67e13b","d174ab98d277d9f5a5611c2c9f419d9f","57edf4a22be3c955ac49da2e2107b67a",};static char *pt(unsigned char *md){int i;static char buf[80];for (i = 0; i < MD5_DIGEST_LENGTH; i++)sprintf(&(buf[i * 2]), "%02x", md[i]);return (buf);}int main(void){int i;char **P, **R;char *p;unsigned char md[MD5_DIGEST_LENGTH];/* 遍历预设值校验 */P = test;R = ret;while (*P != NULL) {printf("calculating MD5 on '%s'\n", *P);EVP_Digest(&(P[0][0]), strlen((char *)*P), md, NULL, EVP_md5(),   NULL);p = pt(md);printf("MD5: %s\n", p);if (strcmp(p, (char *)*R) != 0) {printf("got %s instead of %s\n", p, *R);} elseprintf("test ok\n");printf("\n");R++;P++;}/* 命令行使用md5sum、openssl md5命令的时候会多计算一个'\n'换行符 */printf("calculating MD5 on '%s'\n", "abc\\n");printf("strlen %d\n", strlen("abc\n"));EVP_Digest("abc\n", strlen("abc\n"), md, NULL, EVP_md5(), NULL);p = pt(md);printf("%s\n", p);printf("\n");printf("echo abc | md5sum\n");system("echo abc | md5sum");printf("\n");/* 循环分段计算 */P = test + 5;printf("calculating MD5 on '%s'\n", *P);EVP_MD_CTX ctx;EVP_MD_CTX_init(&ctx);EVP_DigestInit_ex(&ctx, EVP_md5(), NULL);for (i = 0; i < strlen((char *)*P); i++) {EVP_DigestUpdate(&ctx, *P + i, 1);}EVP_DigestFinal_ex(&ctx, md, NULL);EVP_MD_CTX_cleanup(&ctx);p = pt(md);printf("%s\n", p);EVP_MD_CTX_init(&ctx);EVP_DigestInit_ex(&ctx, EVP_md5(), NULL);EVP_DigestUpdate(&ctx, "ABCDEFGHIJKLMNOPQRSTUVWXYZ", strlen("ABCDEFGHIJKLMNOPQRSTUVWXYZ"));EVP_DigestUpdate(&ctx, "abcdefghijklmnopqrstuvwxyz", strlen("abcdefghijklmnopqrstuvwxyz"));EVP_DigestUpdate(&ctx, "0123456789", strlen("0123456789"));EVP_DigestFinal_ex(&ctx, md, NULL);EVP_MD_CTX_cleanup(&ctx);p = pt(md);printf("%s\n", p);ERR_load_crypto_strings();ERR_print_errors_fp(stderr);return 0;}

运行结果

$ gcc -Wall -lcrypto md5.c$ ./a.out calculating MD5 on ''MD5: d41d8cd98f00b204e9800998ecf8427etest okcalculating MD5 on 'a'MD5: 0cc175b9c0f1b6a831c399e269772661test okcalculating MD5 on 'abc'MD5: 900150983cd24fb0d6963f7d28e17f72test okcalculating MD5 on 'message digest'MD5: f96b697d7cb7938d525a2f31aaf161d0test okcalculating MD5 on 'abcdefghijklmnopqrstuvwxyz'MD5: c3fcd3d76192e4007dfb496cca67e13btest okcalculating MD5 on 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'MD5: d174ab98d277d9f5a5611c2c9f419d9ftest okcalculating MD5 on '12345678901234567890123456789012345678901234567890123456789012345678901234567890'MD5: 57edf4a22be3c955ac49da2e2107b67atest okcalculating MD5 on 'abc\n'strlen 40bee89b07a248e27c83fc3d5951213c1echo abc | md5sum0bee89b07a248e27c83fc3d5951213c1  -calculating MD5 on 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'd174ab98d277d9f5a5611c2c9f419d9fd174ab98d277d9f5a5611c2c9f419d9f