import java.io.*;
import java.security.*;
import org.apache.commons.codec.binary.Base64; 

import javax.crypto.spec.SecretKeySpec;
import javax.crypto.Mac;
import org.apache.commons.codec.binary.Hex;

import java.lang.*;         // for String class
import COM.ibm.db2.app.UDF; // UDF classes

public class Xxx  extends UDF {
  public // static String 
    void hmacSha1(String value, String key, String output) 
  {
    try {
      // Get an hmac_sha1 key from the raw key bytes
      byte[] keyBytes = key.getBytes();           
      SecretKeySpec signingKey = new SecretKeySpec(keyBytes, "HmacSHA1");

      // Get an hmac_sha1 Mac instance and initialize with the signing key
      Mac mac = Mac.getInstance("HmacSHA1");
      mac.init(signingKey);

      // Compute the hmac on input data bytes
      byte[] rawHmac = mac.doFinal(value.getBytes());

      // Convert raw bytes to Hex
      byte[] hexBytes = new Hex().encode(rawHmac);

      //  Covert array of Hex bytes to a String
      output = new String(hexBytes, "UTF-8");
      set(3, output);
      // return new String(hexBytes, "UTF-8");
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
  }
}

CALL sqlj.refresh_classes() @
DROP FUNCTION migr.sha1(varchar(), varchar()) @
CREATE or replace FUNCTION migr.sha1(varchar(100), varchar(100))
  RETURNS varchar(500)
  LANGUAGE JAVA
  EXTERNAL NAME 'Xxx!hmacSha1'
  DETERMINISTIC
  FENCED
  NO FINAL CALL
  RETURNS NULL ON NULL INPUT
  NO SQL
  PARAMETER STYLE DB2GENERAL
  NO EXTERNAL ACTION
  DISALLOW PARALLEL
  NO DBINFO
@
VALUES migr.sha1('pwd','key')
@