rabinfingerprint

A Java implementation of the rabin fingerprinting method. (http://en.wikipedia.org/wiki/Rabin_fingerprint)

Optimized for use on a stream including a sliding window fingerprint.

Includes arbitrary-precision-polynomial hashing as well as very fast long-based hashing implementations, which are best for most hashing uses.

Generating a fingerprint

// Create new random irreducible polynomial
// These can also be created from Longs or hex Strings
Polynomial polynomial = Polynomial.createIrreducible(53);

// Create a fingerprint object
RabinFingerprintLong rabin = new RabinFingerprintLong(polynomial);

// Push bytes from a file stream
rabin.pushBytes(ByteStreams.toByteArray(new FileInputStream("file.test")));

// Get fingerprint value and output
System.out.println(Long.toString(rabin.getFingerprintLong(), 16));

Generating a sliding-window fingerprint

// Create new random irreducible polynomial
// These can also be created from Longs or hex Strings
Polynomial polynomial = Polynomial.createIrreducible(53);

// Create a windowed fingerprint object with a window size of 48 bytes.
RabinFingerprintLongWindowed window = new RabinFingerprintLongWindowed(polynomial, 48);
for (byte b : ByteStreams.toByteArray(new FileInputStream("file.test"))) {
	// Push in one byte. Old bytes are automatically popped.
	window.pushByte(b);
	// Output current window's fingerprint
	System.out.println(Long.toString(window.getFingerprintLong(), 16));
}

Building

This project uses Maven for dependency management. To build this project's runnable jar, sources and javadoc, run this command:

% mvn clean install

Command line

Full Usage

Generate a new irreducible polynomial

% java -jar rabinfingerprint.jar -polygen 53
3DE9DD57CA448B

Fingerprint a file

% java -jar rabinfingerprint.jar -p 3DE9DD57CA448B file.test
43A39C59491F /[path to file]/file.test

Fingerprint STDIN

% cat file.test | java -jar rabinfingerprint.jar -p 3DE9DD57CA448B
43A39C59491F