ch.epfl.dedis.lib.crypto.blake2s

Class Blake2sDigest

java.lang.Object

ch.epfl.dedis.lib.crypto.blake2s.Blake2sDigest

All Implemented Interfaces:

org.bouncycastle.crypto.Digest, org.bouncycastle.crypto.ExtendedDigest

public class Blake2sDigest
extends Object
implements org.bouncycastle.crypto.ExtendedDigest

Implementation of the cryptographic hash function BLAKE2s.

BLAKE2s offers a built-in keying mechanism to be used directly for authentication ("Prefix-MAC") rather than a HMAC construction.

BLAKE2s offers a built-in support for a salt for randomized hashing and a personal string for defining a unique hash function for each application.

BLAKE2s is optimized for 32-bit platforms and produces digests of any size between 1 and 32 bytes.

Constructor Summary

Constructors

Constructor and Description
Blake2sDigest() BLAKE2s-256 for hashing.
Blake2sDigest(Blake2sDigest digest)
Blake2sDigest(byte[] key) BLAKE2s for authentication ("Prefix-MAC mode").
Blake2sDigest(byte[] key, int digestBytes, byte[] salt, byte[] personalization) BLAKE2s with key, required digest length, salt and personalization.
Blake2sDigest(int digestBits) BLAKE2s for hashing.

Method Summary

Modifier and Type	Method and Description
void	clearKey() Overwrite the key if it is no longer used (zeroization).
void	clearSalt() Overwrite the salt (pepper) if it is secret and no longer used (zeroization).
int	doFinal(byte[] out, int outOffset) Close the digest, producing the final digest value.
String	getAlgorithmName() Return the algorithm name.
int	getByteLength() Return the size in bytes of the internal buffer the digest applies its compression function to.
int	getDigestSize() Return the size in bytes of the digest produced by this message digest.
void	reset() Reset the digest back to its initial state.
void	update(byte b) Update the message digest with a single byte.
void	update(byte[] message, int offset, int len) Update the message digest with a block of bytes.

Methods inherited from class java.lang.Object

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

Constructor Detail

Blake2sDigest

public Blake2sDigest()

BLAKE2s-256 for hashing.

Blake2sDigest

public Blake2sDigest(Blake2sDigest digest)

Blake2sDigest

public Blake2sDigest(int digestBits)

BLAKE2s for hashing.

Parameters:

digestBits - the desired digest length in bits. Must be a multiple of 8 and less than 256.

Blake2sDigest

public Blake2sDigest(byte[] key)

BLAKE2s for authentication ("Prefix-MAC mode").

After calling the doFinal() method, the key will remain to be used for further computations of this instance. The key can be overwritten using the clearKey() method.

Parameters:

key - a key up to 32 bytes or null

Blake2sDigest

public Blake2sDigest(byte[] key,
                     int digestBytes,
                     byte[] salt,
                     byte[] personalization)

BLAKE2s with key, required digest length, salt and personalization.

After calling the doFinal() method, the key, the salt and the personal string will remain and might be used for further computations with this instance. The key can be overwritten using the clearKey() method, the salt (pepper) can be overwritten using the clearSalt() method.

Parameters:

key - a key up to 32 bytes or null

digestBytes - from 1 up to 32 bytes

salt - 8 bytes or null

personalization - 8 bytes or null

Method Detail

update

public void update(byte b)

Update the message digest with a single byte.

Specified by:

update in interface org.bouncycastle.crypto.Digest

Parameters:

b - the input byte to be entered.

update

public void update(byte[] message,
                   int offset,
                   int len)

Update the message digest with a block of bytes.

Specified by:

update in interface org.bouncycastle.crypto.Digest

Parameters:

message - the byte array containing the data.

offset - the offset into the byte array where the data starts.

len - the length of the data.

doFinal

public int doFinal(byte[] out,
                   int outOffset)

Close the digest, producing the final digest value. The doFinal() call leaves the digest reset. Key, salt and personal string remain.

Specified by:

doFinal in interface org.bouncycastle.crypto.Digest

Parameters:

out - the array the digest is to be copied into.

outOffset - the offset into the out array the digest is to start at.

reset

public void reset()

Reset the digest back to its initial state. The key, the salt and the personal string will remain for further computations.

Specified by:

reset in interface org.bouncycastle.crypto.Digest

getAlgorithmName

public String getAlgorithmName()

Return the algorithm name.

Specified by:

getAlgorithmName in interface org.bouncycastle.crypto.Digest

Returns:

the algorithm name

getDigestSize

public int getDigestSize()

Return the size in bytes of the digest produced by this message digest.

Specified by:

getDigestSize in interface org.bouncycastle.crypto.Digest

Returns:

the size in bytes of the digest produced by this message digest.

getByteLength

public int getByteLength()

Return the size in bytes of the internal buffer the digest applies its compression function to.

Specified by:

getByteLength in interface org.bouncycastle.crypto.ExtendedDigest

Returns:

byte length of the digest's internal buffer.

clearKey

public void clearKey()

Overwrite the key if it is no longer used (zeroization).

clearSalt

public void clearSalt()

Overwrite the salt (pepper) if it is secret and no longer used (zeroization).