如何从PKCS10请求中提取SubjectAlternativeNames

Question

我想从JAVA中的PKCS10请求中提取subject alternative name（SAN）。

首先，我使用bouncycastle获得PKCS10CertificationRequest，如下所示：

PKCS10CertificationRequest certificationRequest = getPKCS10CertificationRequest(csr);

但是，我不知道是否有一种方法可以从认证请求中提取SAN值。

需要帮忙吗？

Answer 1

    byte[] der = Files.readAllBytes(Paths.get(args[0])); // for example
    // assuming all BouncyCastle classes imported as needed and 
    // given a CSR in der, to get the SAN extension as an object
    // (minimal error handling, you may want to improve)
    Attribute[] attrs = new PKCS10CertificationRequest(der).getAttributes(PKCSObjectIdentifiers.pkcs_9_at_extensionRequest);
    if( attrs.length != 1 ) throw new Exception("bad");
    ASN1Encodable[] valus = attrs[0].getAttributeValues();
    if( valus.length != 1 ) throw new Exception("bad");
    Extension extn = Extensions.getInstance(valus[0]).getExtension(Extension.subjectAlternativeName);
    if( extn == null ) throw new Exception("missing");
    // to get the _value_ of the extension, now extn.getExtnValus().getOctets()
    // to _use_ the _value_ of the extension, parse as GeneralNames:
    GeneralNames sanv = GeneralNames.getInstance(extn.getExtnValue().getOctets());
    for( GeneralName item : sanv.getNames() ){ // example of possible usage
        System.out.println (item.toString()); // you probably want something else
    }