Base32 encode UUID in Java

Question

What is the most time efficient way to create and Base32 encode a random UUID in Java? I would like to use Base32 encoding to store globally unique IDs that are usable in URLs.

Answer 1

Base32 still pads with the = character, so you'll need to do something with that if you really want to avoid URL escaping.

If you really want to avoid Base16, I recommend you use Base64 instead of Base32. If you want to use an RFC standard, try base64url. However, that standard also uses "=" for the trailing padding, so you need to escape that. It's substitutions are:

• + -> -
• / -> _
• = -> =

Personally, I use a variant called Y64. It's substitutions are:

• + -> .
• / -> _
• = -> -

It's not an RFC standard, but at least you don't have to worry about escaping the trailing "=".

Apache Commons Codec provides both Base64 and Base32. Here's an example with Base64 with the Y64 variant

To encode:

UUID uuid = UUID.randomUUID();
ByteBuffer uuidBuffer = ByteBuffer.allocate(16);
LongBuffer longBuffer = uuidBuffer.asLongBuffer();
longBuffer.put(uuid.getMostSignificantBits());
longBuffer.put(uuid.getLeastSignificantBits());
String encoded = new String(Base64.encode(uuidBuffer.array()), 
        Charset.forName("US-ASCII"));
encoded = encoded.replace('+', '.')
        .replace('/', '_')
        .replace('=', '-');

And decode:

String encoded; // from your request parameters or whatever
encoded = encoded.replace('.', '+')
        .replace('_', '/')
        .replace('-', '=');
ByteBuffer uuidBuffer = ByteBuffer.wrap(Base64.decode(
        encoded.getBytes(Charset.forName("US-ASCII"))));
LongBuffer longBuffer = uuidBuffer.asLongBuffer();
UUID uuid = new UUID(longBuffer.get(), longBuffer.get());