(Java) Get a Certificate's Key Size

Demonstrates how to get the RSA key size of a certificate (for example, 1024-bit, 2048-bit, etc.)

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    //  For this example, I have a certificate in raw base64 format (not PEM),
    //  that looks like this:  "MIIGkDCCBHigAwIBAgIUMDA ... s/iqLsLA=="
    CkStringBuilder sbCertBase64 = new CkStringBuilder();
    boolean success = sbCertBase64.LoadFile("qa_data/certs/base64Cert.txt","utf-8");

    CkCert cert = new CkCert();
    success = cert.LoadFromBase64(sbCertBase64.getAsString());
    if (success != true) {
        System.out.println(cert.lastErrorText());
        return;
        }

    //  Get the public key.
    CkPublicKey pubKey = cert.ExportPublicKey();
    if (cert.get_LastMethodSuccess() != true) {
        System.out.println(cert.lastErrorText());
        return;
        }

    //  In Chilkat version v9.5.0.67, the KeySize property was added.
    int numBits = pubKey.get_KeySize();
    System.out.println("Number of bits = " + numBits);

    //  If using an older version of Chilkat, the key size can be obtained like this:
    CkXml xml = new CkXml();
    xml.LoadXml(pubKey.getXml());

    CkBinData binDat = new CkBinData();
    binDat.AppendEncoded(xml.getChildContent("Modulus"),"base64");

    numBits = 8 * binDat.get_NumBytes();
    System.out.println("Number of bits = " + numBits);
  }
}