如何使用OpenSSL函数验证PEM证书的密钥长度 [英] How to verify key length of a PEM certificate using openSSL functions

问题描述

如何验证以这种方式生成的PEM证书的密钥长度:

How do I verify the key length of a PEM certificate that is generated in this way:

# openssl genrsa -des3 -out server.key 1024
# openssl req -new -key server.key -out server.csr
# cp server.key server.key.org
# openssl rsa -in server.key.org -out server.key
# openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

我需要的是一个使用来自OpenSSL的过程的C函数，该函数对PEM证书执行验证(我将其用于lighttpd HTTPS服务器)，并返回存储在证书中的密钥的长度(在这种情况下为1024)).

What I need is a C function using procedures from OpenSSL, that performs validation on a PEM certificate (I use it for the lighttpd HTTPS server), and returns the length of the key stored in the certificate (in this case, 1024).

推荐答案

经过一些调整，我相信找到了正确的例程.

After some tweaking, I believe have found the right routines.

以下内容可以帮助您开始探索其他OpenSSL例程，以防您需要处理其他类型的证书( x509 ， pem ).

The following should get you started with exploring other OpenSSL routines, in case you need to handle other types of certificates (x509, pem).

也请通读本地的 x509.h 和 pem.h ，以获取可恢复您所需要的其他信息的结构和功能.

Also read through your local x509.h and pem.h for structures and functions that will recover other information you're after.

/* Compile with 'gcc -Wall -lcrypto foo.c' or similar...
   ---------------------------------------------------------
   $ ./a.out server.crt
   Opened: server.crt
   RSA Public Key: (1024 bit) 

   $ ./a.out server.key
   ERROR: could not read x509 data from server.key                
*/

#include <stdio.h>
#include <openssl/crypto.h>
#include <openssl/x509.h>
#include <openssl/pem.h>

int main(int argc, char *argv[]) 
{
    FILE *fp = NULL;
    X509 *x509 = NULL;
    EVP_PKEY *public_key = NULL;

    fp = fopen(argv[1], "r");
    if (fp) {
        PEM_read_X509(fp, &x509, NULL, NULL);
        fclose(fp);

        if (x509) {
            fprintf(stderr, "Opened PEM certificate file: %s\n", argv[1]);
            /* do stuff with certificate... */
            public_key = X509_get_pubkey(x509);
            if (public_key) {
                switch (public_key->type) {
                    case EVP_PKEY_RSA:
                        fprintf(stdout, "RSA Public Key: (%d bit)\n", BN_num_bits(public_key->pkey.rsa->n));
                        break;
                    default:
                        fprintf(stdout, "Unknown public key type? See OpenSSL documentation\n");
                        break;
                }
                EVP_PKEY_free(public_key);
            }
            X509_free(x509);
        }
        else {
            fprintf(stderr, "ERROR: could not read x509 data from %s\n", argv[1]);
            return EXIT_FAILURE;
        }
    }
    else {
        fprintf(stderr, "ERROR: could not open file!\n");
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

这篇关于如何使用OpenSSL函数验证PEM证书的密钥长度的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！