Java

Decrypt S/MIME and Verify S/MIME Signatures

See more MIME Examples

_LANGUAGE_ example to decrypt S/MIME and verify S/MIME signatures. The S/MIME is unwrapped to get the original MIME prior to signing/encrypting. Java

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[])
  {
    boolean success = false;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    CkMime mime = new CkMime();

    //  Load an S/MIME message from a file:
    success = mime.LoadMimeFile("signedMime.txt");
    if (success == false) {
        System.out.println(mime.lastErrorText());
        return;
        }

    //  The ContainsEncryptedParts/ContainsSignedParts methods
    //  can be called to determine if the MIME is encrypted and/or signed:
    boolean isEncrypted = mime.ContainsEncryptedParts();
    boolean isSigned = mime.ContainsSignedParts();

    //  We don't want the "unwrap extras".  You'll see what those
    //  are in a few moments...
    mime.put_UnwrapExtras(false);

    //  To verify the signature, call UnwrapSecurity.  This will
    //  verify the signature(s) and decrypt the S/MIME and restore
    //  the MIME to the unsigned/unencrypted state.
    //  The results of what was found are present in the MIME object's
    //  properties, as well as extra header fields that are added
    //  to the unwrapped MIME.
    success = mime.UnwrapSecurity();
    if (success != true) {
        //  UnwrapSecurity returns true if all signatures were
        //  verified and all parts decrypted.
        System.out.println(mime.lastErrorText());
        return;
        }

    //  The mime.UnwrapExtras property controls whether or not
    //  these additional fields are added to the unwrapped MIME:
    //  
    //  X-NumPartsSigned: 1
    //  X-SignaturesValid: yes
    //  X-NumPartsEncrypted: 1
    //  X-Decrypted: no
    //  
    //  The X-NumPartsSigned/X-SignaturesValid headers are added
    //  if the MIME was signed.  
    //  
    //  The X-NumPartsEncrypted/X-Decrypted headers are added
    //  if the MIME was encrypted.
    //  

    //  If the MIME was signed, get the certificate used for signing.
    if (isSigned == true) {
        CkCert signerCert = new CkCert();

        //  The NumSignerCerts property indicates how many certificates
        //  were used for signing.  This example will assume the value is 1.
        //  To get the 1st signer cert, call LastSignerCert with an index of 0:
        success = mime.LastSignerCert(0,signerCert);
        if (success == true) {
            System.out.println("**** Signer Cert: " + signerCert.subjectCN());
            }

        }

    //  If the MIME was encrypted, get the certificate used for decryption
    if (isEncrypted == true) {
        //  The NumDecryptCerts property indicates how many certificates
        //  were used for decrypting.  This example will assume the value is 1.
        //  To get the 1st decrypt cert, call LastDecryptCert with an index of 0:
        CkCert decryptCert = new CkCert();
        success = mime.LastDecryptCert(0,decryptCert);
        if (success == true) {
            System.out.println("**** Decrypt Cert: " + decryptCert.subjectCN());
            }

        }

    //  Display the unwrapped MIME:
    System.out.println(mime.getMime());

    //  Save the unwrapped MIME to a file:
    success = mime.SaveMime("unwrappedMime.txt");
  }
}