How to SHA1 hash a string in Android?

In Objective C I've been using the following code to hash a string:

-(NSString *) sha1:(NSString*)stringToHash {	
    const char *cStr = [stringToHash UTF8String];
    unsigned char result[20];
    CC_SHA1( cStr, strlen(cStr), result );
    return [NSString stringWithFormat:@"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",		result[0], result[1], result[2], result[3], 
		result[4], result[5], result[6], result[7],
		result[8], result[9], result[10], result[11],
		result[12], result[13], result[14], result[15],
		result[16], result[17], result[18], result[19]
		];	
}

Now I need the same for Android but can't find out how to do it. I've been looking for example at this: https://stackoverflow.com/questions/5757024/make-sha1-encryption-on-android but that doesn't give me the same result as on iPhone. Can anyone point me in the right direction?

You don't need andorid for this. You can just do it in simple java.

Have you tried a simple java example and see if this returns the right sha1.

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class AeSimpleSHA1 {
    private static String convertToHex(byte[] data) {
        StringBuilder buf = new StringBuilder();
        for (byte b : data) {
            int halfbyte = (b >>> 4) & 0x0F;
            int two_halfs = 0;
            do {
                buf.append((0 <= halfbyte) && (halfbyte <= 9) ? (char) ('0' + halfbyte) : (char) ('a' + (halfbyte - 10)));
                halfbyte = b & 0x0F;
            } while (two_halfs++ < 1);
        }
        return buf.toString();
    }

    public static String SHA1(String text) throws NoSuchAlgorithmException, UnsupportedEncodingException {
        MessageDigest md = MessageDigest.getInstance("SHA-1");
        byte[] textBytes = text.getBytes("iso-8859-1");
        md.update(textBytes, 0, textBytes.length);
        byte[] sha1hash = md.digest();
        return convertToHex(sha1hash);
    }
}

Also share what your expected sha1 should be. Maybe ObjectC is doing it wrong.

A simpler SHA-1 method: (updated from the commenter's suggestions, also using a massively more efficient byte->string algorithm)

String sha1Hash( String toHash )
{
	String hash = null;
	try
	{
		MessageDigest digest = MessageDigest.getInstance( "SHA-1" );
		byte[] bytes = toHash.getBytes("UTF-8");
		digest.update(bytes, 0, bytes.length);
		bytes = digest.digest();

		// This is ~55x faster than looping and String.formating()
		hash = bytesToHex( bytes );
	}
	catch( NoSuchAlgorithmException e )
	{
		e.printStackTrace();
	}
	catch( UnsupportedEncodingException e )
	{
		e.printStackTrace();
	}
	return hash;
}

// http://stackoverflow.com/questions/9655181/convert-from-byte-array-to-hex-string-in-java
final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
public static String bytesToHex( byte[] bytes )
{
	char[] hexChars = new char[ bytes.length * 2 ];
	for( int j = 0; j < bytes.length; j++ )
	{
		int v = bytes[ j ] & 0xFF;
		hexChars[ j * 2 ] = hexArray[ v >>> 4 ];
		hexChars[ j * 2 + 1 ] = hexArray[ v & 0x0F ];
	}
	return new String( hexChars );
}

If you can get away with using Guava it is by far the simplest way to do it, and you don't have to reinvent the wheel:

final HashCode hashCode = Hashing.sha1().hashString(yourValue, Charset.defaultCharset());

You can then take the hashed value and get it as a byte[], as an int, or as a long.

No wrapping in a try catch, no shenanigans. And if you decide you want to use something other than SHA-1, Guava also supports sha256, sha 512, and a few I had never even heard about like adler32 and murmur3.

final MessageDigest digest = MessageDigest.getInstance("SHA-1");
result = digest.digest(stringToHash.getBytes("UTF-8"));

// Another way to construct HEX, my previous post was only the method like your solution
StringBuilder sb = new StringBuilder();

for (byte b : result) // This is your byte[] result..
{
    sb.append(String.format("%02X", b));
}

String messageDigest = sb.toString();

Totally based on @Whymarrh's answer, this is my implementation, tested and working fine, no dependencies:

public static String getSha1Hex(String clearString)
{
    try
    {
        MessageDigest messageDigest = MessageDigest.getInstance("SHA-1");
        messageDigest.update(clearString.getBytes("UTF-8"));
        byte[] bytes = messageDigest.digest();
        StringBuilder buffer = new StringBuilder();
        for (byte b : bytes)
        {
            buffer.append(Integer.toString((b & 0xff) + 0x100, 16).substring(1));
        }
        return buffer.toString();
    }
    catch (Exception ignored)
    {
        ignored.printStackTrace();
        return null;
    }
}

Android comes with Apache's Commons Codec - or you add it as dependency. Then do:

String myHexHash = DigestUtils.shaHex(myFancyInput);

That is the old deprecated method you get with Android 4 by default. The new versions of DigestUtils bring all flavors of shaHex() methods like sha256Hex() and also overload the methods with different argument types.

http://commons.apache.org/proper/commons-codec//javadocs/api-release/org/apache/commons/codec/digest/DigestUtils.html

with Kotlin this can be shortened and put into one line:

MessageDigest.getInstance("SHA-1").digest(theString.toByteArray()).joinToString("") { "%02x".format(it) }

The method you are looking for is not specific to Android, but to Java in general. You're looking for the MessageDigest (import java.security.MessageDigest).

An implementation of a sha512(String s) method can be seen here, and the change for a SHA-1 hash would be changing line 71 to:

MessageDigest md = MessageDigest.getInstance("SHA-1");

Here is the Kotlin version to get SHA encryption string.

import java.security.MessageDigest

object HashUtils {
    fun sha512(input: String) = hashString("SHA-512", input)

    fun sha256(input: String) = hashString("SHA-256", input)

    fun sha1(input: String) = hashString("SHA-1", input)

    /**
     * Supported algorithms on Android:
     *
     * Algorithm	Supported API Levels
     * MD5          1+
     * SHA-1	    1+
     * SHA-224	    1-8,22+
     * SHA-256	    1+
     * SHA-384	    1+
     * SHA-512	    1+
     */
    private fun hashString(type: String, input: String): String {
        val HEX_CHARS = "0123456789ABCDEF"
        val bytes = MessageDigest
                .getInstance(type)
                .digest(input.toByteArray())
        val result = StringBuilder(bytes.size * 2)

        bytes.forEach {
            val i = it.toInt()
            result.append(HEX_CHARS[i shr 4 and 0x0f])
            result.append(HEX_CHARS[i and 0x0f])
        }

        return result.toString()
    }
}

Its originally posted here: https://www.samclarke.com/kotlin-hash-strings/

To simplify it using extentions funcions on kotlin:

/**
 * Encrypt String to SHA1 format
 */
fun String.toSha1(): String {
    return MessageDigest
        .getInstance("SHA-1")
        .digest(this.toByteArray())
        .joinToString(separator = "", transform = { "%02x".format(it) })
}

String.format("%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X", result[0], result[1], result[2], result[3], 
    result[4], result[5], result[6], result[7],
    result[8], result[9], result[10], result[11],
    result[12], result[13], result[14], result[15],
    result[16], result[17], result[18], result[19]);