我使用openSSL庫在C中編寫了一個最簡單的例子sha256
。sha1在C中使用openssl庫的例子
// compile with: gcc -o sha256 sha256.c -lcrypto
#include <openssl/sha.h>
#include <stdio.h>
int main(int argc, char **argv)
{
unsigned char buffer[BUFSIZ];
FILE *f;
SHA256_CTX ctx;
size_t len;
if (argc < 2) {
fprintf(stderr, "usage: %s <file>\n", argv[0]);
return 1;
}
f = fopen(argv[1], "r");
if (!f) {
fprintf(stderr, "couldn't open %s\n", argv[1]);
return 1;
}
SHA256_Init(&ctx);
do {
len = fread(buffer, 1, BUFSIZ, f);
SHA256_Update(&ctx, buffer, len);
} while (len == BUFSIZ);
SHA256_Final(buffer, &ctx);
fclose(f);
for (len = 0; len < SHA256_DIGEST_LENGTH; ++len)
printf("%02x", buffer[len]);
putchar('\n');
return 0;
}
我需要相同的sha1
,但我找不到類似的實際工程的簡單例子。在上面的代碼中用SHA1
代替SHA256
事件的幼稚方法不起作用(顯然)。
如何修改SHA1
的程序?
UPDATE
由@dbush建議,我用他的EVP
代碼,並將其集成到我的程序。我的計劃現在看起來是這樣的:
#include <stdio.h>
#include <openssl/sha.h>
#include <openssl/evp.h>
#include <openssl/err.h>
int main(int argc, char **argv)
{
FILE *f;
size_t len;
unsigned char buffer[BUFSIZ];
if (argc < 2) {
fprintf(stderr, "usage: %s <file>\n", argv[0]);
return 1;
}
f = fopen(argv[1], "r");
if (!f) {
fprintf(stderr, "couldn't open %s\n", argv[1]);
return 1;
}
EVP_MD_CTX hashctx;
//EVP_MD *hashptr = EVP_get_digestbyname("SHA256");
EVP_MD *hashptr = EVP_get_digestbyname("SHA1");
EVP_MD_CTX_init(&hashctx);
EVP_DigestInit_ex(&hashctx, hashptr, NULL));
do {
len = fread(buffer, 1, BUFSIZ, f);
EVP_DigestUpdate(&hashctx, buffer, len);
} while (len == BUFSIZ);
EVP_DigestFinal_ex(&hashctx, buffer, &len);
EVP_MD_CTX_cleanup(&hashctx);
fclose(f);
int i;
for (i = 0; i < len; ++i)
printf("%02x", buffer[i]);
return 0;
}
當我把它用gcc -o evp evp.c -lcrypto
編譯,我得到幾個錯誤,如:
evp.c: In function ‘main’:
evp.c:29:19: warning: initialization discards ‘const’ qualifier from pointer target type [enabled by default]
evp.c:32:43: error: expected ‘;’ before ‘)’ token
evp.c:32:43: error: expected statement before ‘)’ token
evp.c:39:1: warning: passing argument 3 of ‘EVP_DigestFinal_ex’ from incompatible pointer type [enabled by default]
In file included from evp.c:4:0:
/usr/include/openssl/evp.h:574:5: note: expected ‘unsigned int *’ but argument is of type ‘size_t *’
調用兩個OpenSSL的初始化函數如果您所遇到的*「警告:初始化丟棄‘const’限定符......」 *警告,那麼我相信你使用的是真正的老版本的OpenSSL。也許OS X上的OpnSSL 0.9.8?您可能需要考慮更新庫。 – jww
@jww - 我在Debian上使用'libssl-dev'版本'1.0.1t-1 + deb7u1'。 –