code: protected PGPPrivateKey findPrivateKey(PGPSecretKey pgpSecretKey, String password) throws PGPException {
      LOGGER.trace("findPrivateKey(PGPSecretKey, String)");
      LOGGER.trace("Secret Key: {}, Password: {}", pgpSecretKey == null ? "not set" : "set", password == null ? "not set" : "********");
      PGPPrivateKey result = null;
      PBESecretKeyDecryptor pbeSecretKeyDecryptor = new BcPBESecretKeyDecryptorBuilder(new BcPGPDigestCalculatorProvider()).build(password.toCharArray());
      LOGGER.info("Extracting private key");
      result = pgpSecretKey.extractPrivateKey(pbeSecretKeyDecryptor);
      if( result == null && LOGGER.isErrorEnabled() ) {
        LOGGER.error("No private key could be extracted");
      }
      return result;
    }
docs: read the private key from the given secret key
  
  @param pgpSecretKey
  the secret key
  @param password
  the password to unlock the private key
  @return the unlocked private key
  @throws PGPException