unable to extract public key from x509 cert

问题

Here's my code:

import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.io.UnsupportedEncodingException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.X509EncodedKeySpec;
import java.security.KeyFactory;

class LoadKey {
    public static void main(String[] args)
    throws InvalidKeySpecException, UnsupportedEncodingException, NoSuchAlgorithmException
    {
        String cert = "-----BEGIN CERTIFICATE-----\n" +
                      "MIIDITCCAoqgAwIBAgIQT52W2WawmStUwpV8tBV9TTANBgkqhkiG9w0BAQUFADBM\n" +
                      "MQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkg\n" +
                      "THRkLjEWMBQGA1UEAxMNVGhhd3RlIFNHQyBDQTAeFw0xMTEwMjYwMDAwMDBaFw0x\n" +
                      "MzA5MzAyMzU5NTlaMGgxCzAJBgNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlh\n" +
                      "MRYwFAYDVQQHFA1Nb3VudGFpbiBWaWV3MRMwEQYDVQQKFApHb29nbGUgSW5jMRcw\n" +
                      "FQYDVQQDFA53d3cuZ29vZ2xlLmNvbTCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkC\n" +
                      "gYEA3rcmQ6aZhc04pxUJuc8PycNVjIjujI0oJyRLKl6g2Bb6YRhLz21ggNM1QDJy\n" +
                      "wI8S2OVOj7my9tkVXlqGMaO6hqpryNlxjMzNJxMenUJdOPanrO/6YvMYgdQkRn8B\n" +
                      "d3zGKokUmbuYOR2oGfs5AER9G5RqeC1prcB6LPrQ2iASmNMCAwEAAaOB5zCB5DAM\n" +
                      "BgNVHRMBAf8EAjAAMDYGA1UdHwQvMC0wK6ApoCeGJWh0dHA6Ly9jcmwudGhhd3Rl\n" +
                      "LmNvbS9UaGF3dGVTR0NDQS5jcmwwKAYDVR0lBCEwHwYIKwYBBQUHAwEGCCsGAQUF\n" +
                      "BwMCBglghkgBhvhCBAEwcgYIKwYBBQUHAQEEZjBkMCIGCCsGAQUFBzABhhZodHRw\n" +
                      "Oi8vb2NzcC50aGF3dGUuY29tMD4GCCsGAQUFBzAChjJodHRwOi8vd3d3LnRoYXd0\n" +
                      "ZS5jb20vcmVwb3NpdG9yeS9UaGF3dGVfU0dDX0NBLmNydDANBgkqhkiG9w0BAQUF\n" +
                      "AAOBgQAhrNWuyjSJWsKrUtKyNGadeqvu5nzVfsJcKLt0AMkQH0IT/GmKHiSgAgDp\n" +
                      "ulvKGQSy068Bsn5fFNum21K5mvMSf3yinDtvmX3qUA12IxL/92ZzKbeVCq3Yi7Le\n" +
                      "IOkKcGQRCMha8X2e7GmlpdWC1ycenlbN0nbVeSv3JUMcafC4+Q==\n" +
                      "-----END CERTIFICATE-----\n";
        System.out.println(cert);
        byte[] encodedCert = cert.getBytes();
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(encodedCert);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
    }
}

OpenSSL is able to decode the X509 cert via the command line so I know it's a valid cert. But Java doesn't seem to like it, all the same.

I've tired it with and without the trailing \n to no avail.

Any ideas?

回答1:

You were missing the base64 decoding part.

Here's working code, you'll need Apache Commons Codec library for Base64 class.

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.security.PublicKey;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;

import org.apache.commons.codec.binary.Base64;

class LoadKey {
    public static void main(String[] args)
    throws Exception
    {
        String cert = "-----BEGIN CERTIFICATE-----\n" +
                      "MIIDITCCAoqgAwIBAgIQT52W2WawmStUwpV8tBV9TTANBgkqhkiG9w0BAQUFADBM\n" +
                      "MQswCQYDVQQGEwJaQTElMCMGA1UEChMcVGhhd3RlIENvbnN1bHRpbmcgKFB0eSkg\n" +
                      "THRkLjEWMBQGA1UEAxMNVGhhd3RlIFNHQyBDQTAeFw0xMTEwMjYwMDAwMDBaFw0x\n" +
                      "MzA5MzAyMzU5NTlaMGgxCzAJBgNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlh\n" +
                      "MRYwFAYDVQQHFA1Nb3VudGFpbiBWaWV3MRMwEQYDVQQKFApHb29nbGUgSW5jMRcw\n" +
                      "FQYDVQQDFA53d3cuZ29vZ2xlLmNvbTCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkC\n" +
                      "gYEA3rcmQ6aZhc04pxUJuc8PycNVjIjujI0oJyRLKl6g2Bb6YRhLz21ggNM1QDJy\n" +
                      "wI8S2OVOj7my9tkVXlqGMaO6hqpryNlxjMzNJxMenUJdOPanrO/6YvMYgdQkRn8B\n" +
                      "d3zGKokUmbuYOR2oGfs5AER9G5RqeC1prcB6LPrQ2iASmNMCAwEAAaOB5zCB5DAM\n" +
                      "BgNVHRMBAf8EAjAAMDYGA1UdHwQvMC0wK6ApoCeGJWh0dHA6Ly9jcmwudGhhd3Rl\n" +
                      "LmNvbS9UaGF3dGVTR0NDQS5jcmwwKAYDVR0lBCEwHwYIKwYBBQUHAwEGCCsGAQUF\n" +
                      "BwMCBglghkgBhvhCBAEwcgYIKwYBBQUHAQEEZjBkMCIGCCsGAQUFBzABhhZodHRw\n" +
                      "Oi8vb2NzcC50aGF3dGUuY29tMD4GCCsGAQUFBzAChjJodHRwOi8vd3d3LnRoYXd0\n" +
                      "ZS5jb20vcmVwb3NpdG9yeS9UaGF3dGVfU0dDX0NBLmNydDANBgkqhkiG9w0BAQUF\n" +
                      "AAOBgQAhrNWuyjSJWsKrUtKyNGadeqvu5nzVfsJcKLt0AMkQH0IT/GmKHiSgAgDp\n" +
                      "ulvKGQSy068Bsn5fFNum21K5mvMSf3yinDtvmX3qUA12IxL/92ZzKbeVCq3Yi7Le\n" +
                      "IOkKcGQRCMha8X2e7GmlpdWC1ycenlbN0nbVeSv3JUMcafC4+Q==\n" +
                      "-----END CERTIFICATE-----\n";

        cert = cert.replace("-----BEGIN CERTIFICATE-----\n", "");
        cert = cert.replace("-----END CERTIFICATE-----\n", "");
        System.out.println(cert);

        byte[] encodedCert = cert.getBytes("UTF-8");
        byte[] decodedCert = Base64.decodeBase64(encodedCert);
        CertificateFactory certFactory = CertificateFactory.getInstance("X.509");
        InputStream in = new ByteArrayInputStream(decodedCert);
        X509Certificate certificate = (X509Certificate)certFactory.generateCertificate(in);

        System.out.println("Subject DN : " + certificate.getSubjectDN().getName());
        System.out.println("Issuer : " + certificate.getIssuerDN().getName());
        System.out.println("Not After: " + certificate.getNotAfter());
        System.out.println("Not Before: " + certificate.getNotBefore());
        System.out.println("version: " + certificate.getVersion());
        System.out.println("serial number : " + certificate.getSerialNumber());

        PublicKey publicKey = certificate.getPublicKey();
        System.out.println("PublicKey : \n" + publicKey);
    }
}

Output
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Subject DN : CN=www.google.com, O=Google Inc, L=Mountain View, ST=California, C=US
Issuer : CN=Thawte SGC CA, O=Thawte Consulting (Pty) Ltd., C=ZA
Not After: Mon Sep 30 19:59:59 EDT 2013
Not Before: Tue Oct 25 20:00:00 EDT 2011
version: 3
serial number : 105827261859531100510423749949966875981
PublicKey : 
Sun RSA public key, 1024 bits
  modulus: 156396091895984667473837837332877995558144703880815901117439532534031286131520903863087599986938779606924811933611903716377206837300122262900786662124968110191717844999183338594373129421417536020806373385428322642107305024162536996222164292639147591878860587271770855626780464602884552232097424473091745159379
  public exponent: 65537

来源：https://stackoverflow.com/questions/34548957/unable-to-extract-public-key-from-x509-cert