使用openSSL从X509_Extension获取电子邮件地址(主题备用名称的一部分) [英] Get email address (part of Subject Alternative Name) from a X509_Extension with openSSL

问题描述

我有一个iOS应用程序试图从具有OpenSSL的证书中检索SAN.我被困在可以正确获得X509_Extension的部分(我可以检查X509_Extension中的数据，它包含电子邮件地址，并混合有许多其他数据).我不知道如何从X509_Extension中提取电子邮件地址.

I got a iOS application trying to retrieve SAN from a certificate with openSSL. I am stuck at the part that I can get the X509_Extension correctly(I can check the data in the X509_Extension and it contains the email address, mixed in a bunch of other data). I have no idea how to generally extract the email address from the X509_Extension.

任何人都可以帮忙吗?谢谢.以下是我的代码:

Can anyone help? Thanks. Following are my code:

int loc = X509_get_ext_by_NID(cert, NID_subject_alt_name, -1);
if (loc >= 0) {
    X509_EXTENSION * ext = X509_get_ext(cert, loc);
    //How to extract the email address from the ext?
}

推荐答案

受

Inspired by this thread I finally got it solved. FIY:

int loc = X509_get_ext_by_NID(cert, NID_subject_alt_name, -1);

if (loc >= 0) {

    X509_EXTENSION * ext = X509_get_ext(cert, loc);

    BUF_MEM *bptr = NULL;

    char *buf = NULL;

    BIO *bio = BIO_new(BIO_s_mem());

    if(!X509V3_EXT_print(bio, ext, 0, 0)){

        // error handling...

    }

    BIO_flush(bio);

    BIO_get_mem_ptr(bio, &bptr);



    // now bptr contains the strings of the key_usage, take

    // care that bptr->data is NOT NULL terminated, so

    // to print it well, let's do something..

    buf = (char *)malloc( (bptr->length + 1)*sizeof(char) );



    memcpy(buf, bptr->data, bptr->length);

    buf[bptr->length] = '\0';



    NSString *email = [NSString stringWithUTF8String:buf];

    NSRange r1 = [email rangeOfString:@"email:"];

    NSRange r2 = [email rangeOfString:@","];

    NSRange rSub = NSMakeRange(r1.location + r1.length, r2.location - r1.location - r1.length);

    NSString *email = [email substringWithRange:rSub];

}

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