code: private PGPSecretKey readSecretKey(InputStream input) throws LRException
      {
          PGPSecretKeyRingCollection pgpSec;
  
          try
          {
              pgpSec = new PGPSecretKeyRingCollection(PGPUtil.getDecoderStream(input));
          }
          catch (Exception e)
          {
              throw new LRException(LRException.NO_KEY);
          }
  
          java.util.Iterator keyRingIter = pgpSec.getKeyRings();
          while (keyRingIter.hasNext()) {
              PGPSecretKeyRing keyRing = (PGPSecretKeyRing) keyRingIter.next();
  
              java.util.Iterator keyIter = keyRing.getSecretKeys();
              while (keyIter.hasNext()) {
                  PGPSecretKey key = (PGPSecretKey) keyIter.next();
  
                  if (key.isSigningKey()) {
                      return key;
                  }
              }
          }
  
          throw new LRException(LRException.NO_KEY);
      }
docs: Reads private key from the provided InputStream
  
  @param input InputStream of the private key
  @return PGPSecretKey
  @throws LRException NO_KEY error if the key cannot be obtained from the input stream