X509结构，以人类可读的字符串 | 以人类可读的字符串

本文介绍了X509结构，以人类可读的字符串的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我怎么会去用C转换一个X509证书到人类可读的字符串。例如：

  X509 *证书;

到

  ----- BEGIN CERTIFICATE -----
MIIExDCCA6ygAwIBAgIJAK0JmDc / YXWsMA0GCSqGSIb3DQEBBQUAMIGcMQswCQYD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 + 8SKGh49wth3UcH9Nk / YOug7ZvI + tnOcrCZdeG2Ot8Y19Wusf59Y7
q61jSbDWt + 7u7P0ylWWcQfCE9IHSiJIaKAklMu2qGB8bFSPqDyVJuWSwcSXEb9C2
xJsabfgJr6mpfWjCOKd58wFprf0RF58pWHyBqBOiZ2U20PKhq8gPJo / pEpcnXTY0
x8bw8LZ3SrrIQZ5WntFKdB7McFKG9yFfEhUamTKOffQ2Y + SDEGVDj3eshF6 + Fxgj
8plyg3tZPRLSHh5DR42HTc / 35LA52BvjRMWYzrs4nf67gf652pgHh0tFMNMTMgZD
rpTkyts9AgMBAAGjggEFMIIBATAdBgNVHQ4EFgQUG0cLBjouoJPM8dQzKUQCZYNY
y8AwgdEGA1UdIwSByTCBxoAUG0cLBjouoJPM8dQzKUQCZYNYy8ChgaKkgZ8wgZwx
CzAJBgNVBAYTAklOMQswCQYDVQQIEwJBUDEMMAoGA1UEBxMDSFlEMRkwFwYDVQQK
ExBSb2Nrd2VsbCBjb2xsaW5zMRwwGgYDVQQLExNJbmRpYSBEZXNpZ24gQ2VudGVy
MQ4wDAYDVQQDEwVJTUFDUzEpMCcGCSqGSIb3DQEJARYaYnJhamFuQFJvY2t3ZWxs
Y29sbGlucy5jb22CCQCtCZg3P2F1rDAMBgNVHRMEBTADAQH / MA0GCSqGSIb3DQEB
BQUAA4IBAQCyYZxEzn7203no9TdhtKDWOFRwzYvY2kZppQ / EpzF + pzh8LdBOebr +
DLRXNh2NIFaEVV0brpQTI4eh6b5j7QyF2UmA6 + 44zmku9LzS9DQVKGLhIleB436K
ARoWRqxlEK7TF3TauQfaalGH88ZWoDjqqEP / 5oWeQ6pr / RChkCHkBSgq6FfGGSLd
ktgFcF0S9U7Ybii / MD + tWMImK8EE3GGgs876yqX / DDhyfW8DfnNZyl35VF / 80J /秒
0Lj3F7Po1zsaRbQlhOK5rzRVQA2qnsa4IcQBuYqBWiB6XojPgu9PpRSL7ure7sj6
gRQT0OIU5vXzsmhjqKoZ + dBlh1FpSOX2
----- END CERTIFICATE -----

解决方案

X509结构的转换与PEM字符串连接codeD证书：

 的char * X509_to_PEM（X509 *证书）{    BIO *生物= NULL;
    字符* PEM = NULL;    如果（NULL == CERT）{
        返回NULL;
    }    生物= BIO_new（BIO_s_mem（））;
    如果（NULL ==生物）{
        返回NULL;
    }    如果（0 == PEM_write_bio_X509（生物，证书））{
        BIO_free（生物）;
        返回NULL;
    }    PEM =（字符*）malloc的（生物＆GT; num_write + 1）;
    如果（NULL == PEM）{
        BIO_free（生物）;
        返回NULL;
    }    memset的（PEM，0，生物＆GT; num_write + 1）;
    BIO_READ（生物，PEM，生物＆GT; num_write）;
    BIO_free（生物）;
    返回PEM;
}

PEM的转换连接codeD证书到X509结构：

  X509 * PEM_to_X509（字符* PEM）{    X509 *证书= NULL;
    BIO *生物= NULL;    如果（NULL == PEM）{
        返回NULL;
    }    生物= BIO_new_mem_buf（PEM，strlen的（PEM））;
    如果（NULL ==生物）{
        返回NULL;
    }    证书= PEM_read_bio_X509（生物，NULL，NULL，NULL）;
    BIO_free（生物）;
    返回证书;
}

How would I go about converting a X509 certificate in C into human readable string. For example:

X509* cert;

into

解决方案

Conversion of X509 structure to the string with PEM encoded certificate:

char *X509_to_PEM(X509 *cert) {

    BIO *bio = NULL;
    char *pem = NULL;

    if (NULL == cert) {
        return NULL;
    }

    bio = BIO_new(BIO_s_mem());
    if (NULL == bio) {
        return NULL;
    }

    if (0 == PEM_write_bio_X509(bio, cert)) {
        BIO_free(bio);
        return NULL;
    }

    pem = (char *) malloc(bio->num_write + 1);
    if (NULL == pem) {
        BIO_free(bio);
        return NULL;
    }

    memset(pem, 0, bio->num_write + 1);
    BIO_read(bio, pem, bio->num_write);
    BIO_free(bio);
    return pem;
}

Conversion of PEM encoded certificate to the X509 structure:

X509 *PEM_to_X509(char *pem) {

    X509 *cert = NULL;
    BIO *bio = NULL;

    if (NULL == pem) {
        return NULL;
    }

    bio = BIO_new_mem_buf(pem, strlen(pem));
    if (NULL == bio) {
        return NULL;
    }

    cert = PEM_read_bio_X509(bio, NULL, NULL, NULL);
    BIO_free(bio);
    return cert;
}

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