Base64

Base64 is a freeware way of encoding 8-bit characters using

only ASCII printable characters similar to UUENCODE.

UUENCODE embeds a filename where BASE64 does not. You will

see BASE64 used in encoding digital certificates, in

encoding user:password string in an Authorization: header

for HTTP. The spec is described in RFC 2045.

Don't confuse Base64 with x-www-form-urlencoded which

is handled by java.net.URLEncoder.encode/decode or

Base64u.

Base64 armouring uses only the characters A-Z a-z 0-9 +/=.

This makes it suitable for encoding binary data as SQL

strings, that will work no matter what the encoding.

Unfortunately + / and = all have special meaning in URLs.

Base64u gets around this problem. It is a variant on Base64

that uses - _ and * in preference to + / and =, so that it

can be used in URLEncoded contexts with or without

URLEncoding.

Use base64 like this:

// Base64 armouring

import com.mindprod.base64.Base64;

...

// sample byte array to encode

byte[] toSend = { (byte)0xfc, (byte)0x0f, (byte)0xc0};

// create encoder object

Base64 base64 = new Base64();

base64.setLineLength( 72 ); // default

// encoding a byte[]

String send = base64.encoder( toSend );

// decoding a byte[]

byte[] reconstituted = base64.decoder( sent );

use Base64u the same way:

// Base64u armouring

import com.mindprod.base64.Base64u;

...

// sample byte array to encode

byte[] toSend = { (byte)0xfc, (byte)0x0f, (byte)0xc0};

// create encoder object

Base64u base64u = new Base64u();

base64u.setLineLength( 72 ); // default

// encoding a byte[]

String send = base64u.encoder( toSend );

// decoding a byte[]

byte[] reconstituted = base64u.decoder( sent );

For an example that starts and ends with a String, see

Example.java

to run:

java.exe com.mindprod.base64.Example