Java calculate hex representation of a SHA-1 digest of a String

If you don't want to add any extra dependencies to your project, you could also use

MessageDigest digest = MessageDigest.getInstance("SHA-1");
digest.update(message.getBytes("utf8"));
byte[] digestBytes = digest.digest();
String digestStr = javax.xml.bind.DatatypeConverter.printHexBinary(digestBytes);

Using apache common codec library:

DigestUtils.sha1Hex("aff")

The result is 0c05aa56405c447e6678b7f3127febde5c3a9238

That's it :)

This is happening because cript.digest() returns a byte array, which you're trying to print out as a character String. You want to convert it to a printable Hex String.

Easy solution: Use Apache's commons-codec library:

String password = new String(Hex.encodeHex(cript.digest()),
                             CharSet.forName("UTF-8"));

One iteration of a hash algorithm is not secure. It's too fast. You need to perform key strengthening by iterating the hash many times.

Furthermore, you are not salting the password. This creates a vulnerability to pre-computed dictionaries, like "rainbow tables."

Instead of trying to roll your own code (or using some sketchy third-party bloatware) to do this correctly, you can use code built-in to the Java runtime. See this answer for details.

Once you have hashed the password correctly, you'll have a byte[]. An easy way to convert this to a hexadecimal String is with the BigInteger class:

String passwordHash = new BigInteger(1, cript.digest()).toString(16);

If you want to make sure that your string always has 40 characters, you may need to do some padding with zeroes on the left (you could do this with String.format().)