code: private void readTrustStore(Configuration conf) throws IOException, FormatNotUnderstoodException {
  	if (((this.hocr.getSigTruststoreFile()!=null) && (!"".equals(this.hocr.getSigTruststoreFile())))) {
  		LOG.info("Reading truststore to validate certificate chain for signatures");
  		HadoopKeyStoreManager hksm = new HadoopKeyStoreManager(conf);
  		try {
  			hksm.openKeyStore(new Path(this.hocr.getSigTruststoreFile()), this.hocr.getSigTruststoreType(), this.hocr.getSigTruststorePassword());
  			this.hocr.setX509CertificateChain(hksm.getAllX509Certificates());
  		} catch (NoSuchAlgorithmException | CertificateException | KeyStoreException | IllegalArgumentException e) {
  			LOG.error("Cannopt read truststore. Exception: ",e);
  			throw new FormatNotUnderstoodException("Cannot read truststore to establish certificate chain for signature validation "+e);
  		}
  		
  	}
  }
docs: *
  Read truststore for establishing certificate chain for signature validation
  
  @param conf
  @throws IOException
  @throws FormatNotUnderstoodException