de.profhenry.sshsig.core

Class SshSignatureGenerator<K>

java.lang.Object

de.profhenry.sshsig.core.SshSignatureGenerator<K>

Type Parameters:

K - the type for the key information

public final class SshSignatureGenerator<K>
extends Object

Generator for SSH signatures.

This implements the OpenSSH lightweight signature ability introduced with OpenSSH 8.1. It allows to sign messages using SSH keys according to the SSHSIG protocol.

Features:

• Content to be signed can be provided as string, byte array, file or as input stream
• Supported ssh key types: DSA, RSA, Ed25519
• Supported hashing algorithms: SHA-256 and SHA-512 (default SHA.512)
• Pluggable signing backend (default JCA)

Usage:

 KeyPairGenerator tKeyPairGenerator = KeyPairGenerator.getInstance("RSA");
 KeyPair tKeyPair = tKeyPairGenerator.generateKeyPair();
 SshSignatureGenerator.create().generateSignature(tKeyPair, "namespace", "a message");
 

Author:

profhenry

Method Summary

Modifier and Type	Method and Description
static SshSignatureGenerator<KeyPair>	create() Factory method for creating a SSH signature generator.
SshSignature	generateSignature(K aKey, String aNamespace, byte[] aMessage) Generates a SSH signature for a byte message.
SshSignature	generateSignature(K aKey, String aNamespace, File aFile) Generates a SSH signature for the content of a file.
SshSignature	generateSignature(K aKey, String aNamespace, InputStream anInputStream) Generates a SSH signature for data provided by an input stream.
SshSignature	generateSignature(K aKey, String aNamespace, String aMessage) Generates a SSH signature for a string message.
int	getBufferSize()
HashAlgorithm	getHashAlgorithm()
SshPublicKeyEncoder	getPublicKeyEncoder()
SigningBackend<K>	getSigningBackend()
SshSignatureGenerator<K>	withBufferSize(int aBufferSize)
SshSignatureGenerator<K>	withHashAlgorithm(HashAlgorithm aHashAlgorithm)
SshSignatureGenerator<K>	withPublicKeyEncoder(SshPublicKeyEncoder aPublicKeyEncoder)
<KK> SshSignatureGenerator<KK>	withSigningBackend(SigningBackend<KK> aSigningBackend)

Methods inherited from class java.lang.Object

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

Method Detail

getSigningBackend

public SigningBackend<K> getSigningBackend()

getPublicKeyEncoder

public SshPublicKeyEncoder getPublicKeyEncoder()

getHashAlgorithm

public HashAlgorithm getHashAlgorithm()

getBufferSize

public int getBufferSize()

generateSignature

public SshSignature generateSignature(K aKey,
                                      String aNamespace,
                                      String aMessage)
                               throws SshSignatureException

Generates a SSH signature for a string message.

Parameters:

aKey - the SSH key

aNamespace - the namespace

aMessage - the string message

Returns:

the SSH signature

Throws:

SshSignatureException - in case signature generation failed

generateSignature

public SshSignature generateSignature(K aKey,
                                      String aNamespace,
                                      byte[] aMessage)
                               throws SshSignatureException

Generates a SSH signature for a byte message.

Parameters:

aKey - the SSH key

aNamespace - the namespace

aMessage - the byte message

Returns:

the SSH signature

Throws:

SshSignatureException - in case signature generation failed

generateSignature

public SshSignature generateSignature(K aKey,
                                      String aNamespace,
                                      File aFile)
                               throws IOException,
                                      SshSignatureException

Generates a SSH signature for the content of a file.

Parameters:

aKey - the SSH key

aNamespace - the namespace

aFile - the file

Returns:

the SSH signature

Throws:

IOException - in case reading from file failed

SshSignatureException - in case signature generation failed

generateSignature

public SshSignature generateSignature(K aKey,
                                      String aNamespace,
                                      InputStream anInputStream)
                               throws IOException,
                                      SshSignatureException

Generates a SSH signature for data provided by an input stream.

Parameters:

aKey - the key

aNamespace - the namespace

anInputStream - the inputstream

Returns:

the SSH signature

Throws:

IOException - in case reading from input stream failed

SshSignatureException - in case signature generation failed

create

public static SshSignatureGenerator<KeyPair> create()

Factory method for creating a SSH signature generator.

The created generator uses the following default configuration

• JCA signing backend
• default SSH public key encoder
• SHA_512 for hashing messages
• 8k buffer size when reading messages from an input stream

The with... Methodes can be used for altering the default config.

Returns:

the SSH signature generator

withSigningBackend

public <KK> SshSignatureGenerator<KK> withSigningBackend(SigningBackend<KK> aSigningBackend)

withPublicKeyEncoder

public SshSignatureGenerator<K> withPublicKeyEncoder(SshPublicKeyEncoder aPublicKeyEncoder)

withHashAlgorithm

public SshSignatureGenerator<K> withHashAlgorithm(HashAlgorithm aHashAlgorithm)

withBufferSize

public SshSignatureGenerator<K> withBufferSize(int aBufferSize)