org.kocakosm.jblake2

Class Blake2s

java.lang.Object

org.kocakosm.jblake2.Blake2s

All Implemented Interfaces:

Blake2

public final class Blake2s
extends Object
implements Blake2

The BLAKE2s digest algorithm. This BLAKE2 flavor is optimized for 8 to 32-bit platforms and produces digests of any size between 1 and 32 bytes. This class implements the BLAKE2s algorithm as specified in RFC 7693. The original paper defines some additional variants with features such as salting, personalization and tree hashing. These features are considered optional and not covered by the RFC. BLAKE2s can be directly keyed, making it functionally equivalent to a Message Authentication Code (it does not require a special construction like HMAC). Instances of this class are not thread safe.

Author:

Osman Koçak

See Also:

blake2.net, RFC 7693

Constructor Summary

Constructors

Constructor and Description
Blake2s(int digestLength) Creates a new unkeyed Blake2s instance.
Blake2s(int digestLength, byte[] key) Creates a new keyed Blake2s instance.

Method Summary

Modifier and Type	Method and Description
String	algorithm() Returns the algorithm name.
void	burn() Erases the key and resets the digest, thus making this instance functionally equivalent to a newly created unkeyed digest.
Blake2s	copy() Returns a copy of this object.
byte[]	digest() Completes the digest computation.
int	length() Returns the digest's length (in bytes).
Blake2s	reset() Resets the digest.
Blake2s	update(byte... input) Updates the digest using the given array of bytes.
Blake2s	update(byte input) Updates the digest using the given byte.
Blake2s	update(byte[] input, int off, int len) Updates the digest using the specified number of bytes from the given array, starting at the specified offset.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.kocakosm.jblake2.Blake2

digest, digest

Constructor Detail

Blake2s

public Blake2s(int digestLength)

Creates a new unkeyed Blake2s instance.

Parameters:

digestLength - the desired digest's length (in bytes).

Throws:

IllegalArgumentException - if digestLength is not in the [1, 32] range.

Blake2s

public Blake2s(int digestLength,
               byte[] key)

Creates a new keyed Blake2s instance. If the key is empty, then the created instance is equivalent to an unkeyed digest. The given key can be safely erased from memory after this constructor has been called.

Parameters:

digestLength - the desired digest's length (in bytes).

key - the key to use.

Throws:

NullPointerException - if key is null.

IllegalArgumentException - if key's length is greater than 32 or if digestLength is not in the [1, 32] range.

Method Detail

algorithm

public String algorithm()

Description copied from interface: Blake2

Returns the algorithm name.

Specified by:

algorithm in interface Blake2

Returns:

the algorithm name.

burn

public void burn()

Description copied from interface: Blake2

Erases the key and resets the digest, thus making this instance functionally equivalent to a newly created unkeyed digest. If this instance is already unkeyed, calling this method has no other effect than resetting the digest. Please note that this method can only guarantee that the active copy of the key is erased. Indeed, in practice, an object may have several copies of itself in physical RAM. This is mainly due to the fact that most modern garbage collection algorithms regularly "move" objects in memory. This method is primarily here because it is still considered a good practice to erase sensitive information as soon as possible.

Specified by:

burn in interface Blake2

copy

public Blake2s copy()

Description copied from interface: Blake2

Returns a copy of this object.

Specified by:

copy in interface Blake2

Returns:

a copy of this object.

length

public int length()

Description copied from interface: Blake2

Returns the digest's length (in bytes).

Specified by:

length in interface Blake2

Returns:

the digest's length (in bytes).

reset

public Blake2s reset()

Description copied from interface: Blake2

Resets the digest. Note that this does not erase the key.

Specified by:

reset in interface Blake2

Returns:

this object.

update

public Blake2s update(byte input)

Description copied from interface: Blake2

Updates the digest using the given byte.

Specified by:

update in interface Blake2

Parameters:

input - the byte with which to update the digest.

Returns:

this object.

update

public Blake2s update(byte... input)

Description copied from interface: Blake2

Updates the digest using the given array of bytes.

Specified by:

update in interface Blake2

Parameters:

input - the array of bytes with which to update the digest.

Returns:

this object.

update

public Blake2s update(byte[] input,
                      int off,
                      int len)

Description copied from interface: Blake2

Updates the digest using the specified number of bytes from the given array, starting at the specified offset.

Specified by:

update in interface Blake2

Parameters:

input - the array of bytes.

off - the offset to start from in the array, inclusive.

len - the number of bytes to use, starting at off.

Returns:

this object.

digest

public byte[] digest()

Description copied from interface: Blake2

Completes the digest computation. Note that this digest is reset after this call is made.

Specified by:

digest in interface Blake2

Returns:

the resulting digest.