Android How to - Get SHA 256, SHA-1 hash value

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Question

We would like to know how to get SHA 256, SHA-1 hash value.

Answer

/* //from  w w w .  j av a  2 s .co  m
 * CryptoUtil.java        0.1.6 03/08/12
 * 
 * Licensed to the Apache Software Foundation (ASF) under one 
 * or more contributor license agreements.  See the NOTICE file 
 * distributed with this work for additional information 
 * regarding copyright ownership.  The ASF licenses this file 
 * to you under the Apache License, Version 2.0 (the 
 * "License"); you may not use this file except in compliance 
 * with the License.  You may obtain a copy of the License at 
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0 
 * d
 * Unless required by applicable law or agreed to in writing, 
 * software distributed under the License is distributed on an 
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 
 * KIND, either express or implied.  See the License for the 
 * specific language governing permissions and limitations 
 * under the License. 
 */

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.UUID;

/**
 * Utility class that provides cryptographic algorithms.
 * 
 * @author Ingo Bente, Tobias Ruhe (FHH)
 * @version 0.1.6
 * 
 */
public class Main {

  /**
   * Calculate a hash value for the given {@link String} s with the specified
   * algorithm dig.
   * 
   * @param s
   * @param mdId
   * @return the hashed value. if problems do occur, the an empty {@link String} is returned 
   */
  private static String hash(String s, MessageDigestId mdId) {
    StringBuffer buffer = new StringBuffer();
    MessageDigest md = null;
    byte[] hash;
    // check input string
    if (s == null) {
      return buffer.toString();
    }
    // calculate digest
    try {
      md = MessageDigest.getInstance(mdId.toString());
      buffer = new StringBuffer();
      hash = md.digest(s.getBytes());
      for (Byte b : hash) {
        String hex = Integer.toHexString(0xFF & b);
        if (hex.length() == 1)
          buffer.append(0);
        buffer.append(hex);
      }
    } catch (NoSuchAlgorithmException e) {
    }
    
    return buffer.toString();
  }

  /**
   * Get the SHA-1 hash of the given {@link String}
   * @param s
   * @return
   */
  public static String sha1(String s) {
    return hash(s, MessageDigestId.SHA1);
  }
  
  /**
   * Get the SHA256 hash of the given {@link String}
   * @param s
   * @return
   */
  public static String sha256(String s) {
    return hash(s, MessageDigestId.SHA256);
  }

  /**
   * Get the MD5 hash of the given {@link String}
   * @param s
   * @return
   */
  public static String md5(String s) {
    return hash(s, MessageDigestId.MD5);
  }

  
  /**
   * Get a random UUID of the given length
   * @param length
   * @return null if lenght <= 0
   */
  public static String randomUUID(int length) {
    if (length > 0) {
      String uuid = UUID.randomUUID().toString();
      if (uuid.length() <= length)
        return uuid;
      else
        return uuid.substring(0, length - 1);
    } else
      return null;
  }

  /**
   * Identifiers for message digest algorithms.
   * 
   * @author Ingo Bente (FHH)
   * 
   */
  private enum MessageDigestId {
    SHA256("SHA-256"), MD5("MD5"), SHA1("SHA-1");

    private final String name;

    private MessageDigestId(String name) {
      this.name = name;
    }

    @Override
    public String toString() {
      return this.name;
    }
  }
}

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