BouncyCastle：从证书中提取公钥导致NullPointerException

Question

import com.security.crypto.Configuration.Properties; 
import org.apache.commons.codec.binary.Base64; 
import org.bouncycastle.asn1.ASN1InputStream; 
import org.bouncycastle.asn1.ASN1Primitive; 
import org.bouncycastle.asn1.ASN1Sequence; 
import org.bouncycastle.asn1.x509.Certificate; 
import org.bouncycastle.jce.provider.X509CertificateObject; 

import java.io.ByteArrayInputStream; 
import java.io.IOException; 
import java.security.GeneralSecurityException; 
import java.security.PublicKey; 
import java.security.cert.X509Certificate; 

/** 
* Hello world! 
*/ 
public class App { 
    public static void main(String[] args) throws Exception { 

String df="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"; 
    X509Certificate cert = loadCertificate(df); 
    System.out.println(cert.getSigAlgName());//SHA1withRSA 
    PublicKey key=cert.getPublicKey(); 
    System.out.println(key.getAlgorithm());//java.lang.NullPointerException 
    } 

    public static X509Certificate loadCertificate(String asn1)throws IOException, GeneralSecurityException 
    { 
     byte []data=Base64.decodeBase64(asn1.getBytes(Properties.CHAR_ENCODING)); 
     ByteArrayInputStream inStream = new ByteArrayInputStream(data); 
     ASN1InputStream derin = new ASN1InputStream(inStream); 
     ASN1Primitive certInfo = derin.readObject(); 
     ASN1Sequence seq = ASN1Sequence.getInstance(certInfo); 
     return new X509CertificateObject(Certificate.getInstance(seq)); 
    } 
} 

我正在使用BouncyCastle从DER编码生成X509Certificate。一切看起来不错，证书随着成功加载。但是，当我尝试从证书获得公钥时，我得到了NullpointerException，当我试图使用密钥就像上面的例子。这里发生了什么？

SHA1withRSA 
Exception in thread "main" java.lang.NullPointerException 
    at com.security.crypto.App.main(App.java:28) 

Answer 1

由于我不完全清楚的原因，您必须添加Bouncycastle JCE提供程序。所以，在主要的开始，你需要

Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());