How to generate an MD5 checksum for a file in Android?

Question

In my app I have a requirement to generate an MD5 checksum for a file. Could you please tell me if there is any way in which this can be achieved?

Thank you.

Answer 1

This code is from the CMupdater, from the CyanogenMod 10.2 android ROM. It tests the downloaded ROMs into the updater App.

code: https://github.com/CyanogenMod/android_packages_apps_CMUpdater/blob/cm-10.2/src/com/cyanogenmod/updater/utils/MD5.java

It works like a charm:

/*  * Copyright (C) 2012 The CyanogenMod Project  *  * * Licensed under the GNU GPLv2 license  *  * The text of the license can be found in the LICENSE file  * or at https://www.gnu.org/licenses/gpl-2.0.txt  */  package com.cyanogenmod.updater.utils;  import android.text.TextUtils; import android.util.Log;  import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.math.BigInteger; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException;  public class MD5 {     private static final String TAG = "MD5";      public static boolean checkMD5(String md5, File updateFile) {         if (TextUtils.isEmpty(md5) || updateFile == null) {             Log.e(TAG, "MD5 string empty or updateFile null");             return false;         }          String calculatedDigest = calculateMD5(updateFile);         if (calculatedDigest == null) {             Log.e(TAG, "calculatedDigest null");             return false;         }          Log.v(TAG, "Calculated digest: " + calculatedDigest);         Log.v(TAG, "Provided digest: " + md5);          return calculatedDigest.equalsIgnoreCase(md5);     }      public static String calculateMD5(File updateFile) {         MessageDigest digest;         try {             digest = MessageDigest.getInstance("MD5");         } catch (NoSuchAlgorithmException e) {             Log.e(TAG, "Exception while getting digest", e);             return null;         }          InputStream is;         try {             is = new FileInputStream(updateFile);         } catch (FileNotFoundException e) {             Log.e(TAG, "Exception while getting FileInputStream", e);             return null;         }          byte[] buffer = new byte[8192];         int read;         try {             while ((read = is.read(buffer)) > 0) {                 digest.update(buffer, 0, read);             }             byte[] md5sum = digest.digest();             BigInteger bigInt = new BigInteger(1, md5sum);             String output = bigInt.toString(16);             // Fill to 32 chars             output = String.format("%32s", output).replace(' ', '0');             return output;         } catch (IOException e) {             throw new RuntimeException("Unable to process file for MD5", e);         } finally {             try {                 is.close();             } catch (IOException e) {                 Log.e(TAG, "Exception on closing MD5 input stream", e);             }         }     } } 

Answer 2

Convert the file content into string & use the below method:

public static String getMD5EncryptedString(String encTarget){         MessageDigest mdEnc = null;         try {             mdEnc = MessageDigest.getInstance("MD5");         } catch (NoSuchAlgorithmException e) {             System.out.println("Exception while encrypting to md5");             e.printStackTrace();         } // Encryption algorithm         mdEnc.update(encTarget.getBytes(), 0, encTarget.length());         String md5 = new BigInteger(1, mdEnc.digest()).toString(16);         while ( md5.length() < 32 ) {             md5 = "0"+md5;         }         return md5;     } 

Note that this simple approach is suitable for smallish strings, but will not be efficient for large files. For the latter, see dentex's answer.