如何使用OpenSSL从证书中提取所有OID

Question

我有一个问题,不知道如何解决它.我在ExtendedKeyUsage扩展中有一个带有自定义OID(对象标识符)的X.509v3证书.如何从ExtendedKeyUsage使用OpenSSL 1.1.0中提取所有OID ？

例如,我在ExtendedKeyUsage扩展中创建了一个带有3个标志的证书:

"clientAuth, 1.3.6.1.5.5.7.3.103, timeStamping"

clientAuth并timeStamping以OpenSSL 而闻名.中间的标志是我的自定义OID.我添加了OpenSSL函数的所有标志X509V3_EXT_conf_nid().好的......就所有工作而言.

现在,我试图提取与OID的X509_get_extended_key_usage(cert),但我只得到clientAuth和timeStamping.

现在我将ExtendedKeyUsage中的原始数据解压缩为ASN1_OCTET_STRING,如下所示:

int size;
unsigned char *data;
ASN1_OCTET_STRING *os;
X509_EXTENSION *ext;

// extracting data from certificate extension
ext = X509_get_ext(cert, 2);
os = X509_EXTENSION_get_data(ext);

size = ASN1_STRING_length(os);
data = ASN1_STRING_data(os);

这是data十六进制的内容:30:1E:06:08:2B:06:01:05:05:07:03:02:06:08:2B:06:01:05:05:07:03:67:06:08:2B:06:01:05:05:07:03:08.

如果我用外部工具解码这个十六进制字符串,那么我得到这个:

Offset|Length|LenByte|
======+======+===================================================
     0|    30|      1|   SEQUENCE : 
     2|     8|      1|      OBJECT_IDENTIFIER : '1.3.6.1.5.5.7.3.2'    (id-kp-clientAuth)
    12|     8|      1|      OBJECT_IDENTIFIER : '1.3.6.1.5.5.7.3.103'
    22|     8|      1|      OBJECT_IDENTIFIER : '1.3.6.1.5.5.7.3.8'    (id-kp-timeStamping)

我的OID可用,但我如何在OpenSSL中提取此OID？我可以解析它......以及如何解决？:(

提前谢谢你.

Answer 1

我找到了解决方案!

这是我的快速和愚蠢的代码:

// optional: we can set an OID name
OBJ_create("1.3.6.1.5.5.7.3.103", "myObjectShortName", "myObjectLongName");

// find the extendedKeyUsage
int extIndex = X509_get_ext_by_NID(cert, NID_ext_key_usage, -1);
if (extIndex < 0)
    std::cerr << "extendedKeyUsage is not present";

// get the correct X.509 extension
X509_EXTENSION *ext = X509_get_ext(cert, extIndex);
if (!ext)
    std::cerr << "'ext' is a nullptr";

// get the extendedKeyUsage
EXTENDED_KEY_USAGE *eku = static_cast<EXTENDED_KEY_USAGE*>(X509V3_EXT_d2i(ext));
if (!eku)
    std::cerr << "'eku' is a nullptr";

// print all OIDs
for (int i = 0; i < sk_ASN1_OBJECT_num(eku); i++)
{
    char buffer[100];
    OBJ_obj2txt(buffer, sizeof(buffer), sk_ASN1_OBJECT_value(eku, i), 1); // get OID

    std::cout << "eku flag " << i << ": " << buffer << "\t - ";
    std::cout << OBJ_nid2ln(OBJ_obj2nid(sk_ASN1_OBJECT_value(eku, i))) << std::endl; // get OID name
}

// free used resource
if (eku)
    EXTENDED_KEY_USAGE_free(eku);

输出:

eku flag 0: 1.3.6.1.5.5.7.3.2    - TLS Web Client Authentication
eku flag 1: 1.3.6.1.5.5.7.3.103  - myObjectLongName
eku flag 2: 1.3.6.1.5.5.7.3.8    - Time Stamping

也许这段代码可以帮助别人