Package org.apache.sshd.common.kex

Enum MontgomeryCurve

java.lang.Object

java.lang.Enum<MontgomeryCurve>

org.apache.sshd.common.kex.MontgomeryCurve

All Implemented Interfaces:

java.io.Serializable, java.lang.Comparable<MontgomeryCurve>, CurveSizeIndicator, KeySizeIndicator, OptionalFeature

public enum MontgomeryCurve
extends java.lang.Enum<MontgomeryCurve>
implements KeySizeIndicator, CurveSizeIndicator, OptionalFeature

Provides implementation details for Montgomery curves and their key exchange algorithms Curve25519/X25519 and Curve448/X448 specified in RFC 7748 and RFC 8731. Montgomery curves provide improved security and flexibility over Weierstrass curves used in ECDH.

See Also:

RFC 7748, RFC 8731

Enum Constant Summary

Enum Constants

Enum Constant	Description
x25519	X25519 uses Curve25519 and SHA-256 with a 32-byte key size.
x448	X448 uses Curve448 and SHA-512 with a 56-byte key size.

Field Summary

Fields

Modifier and Type	Field	Description
private java.lang.String	algorithm
private byte[]	encodedPublicKeyPrefix
private java.security.KeyFactory	keyFactory
private java.security.KeyPairGenerator	keyPairGenerator
private int	keySize
private boolean	supported

Fields inherited from interface org.apache.sshd.common.OptionalFeature

FALSE, TRUE

Constructor Summary

Constructors

Modifier	Constructor	Description
private	MontgomeryCurve(java.lang.String algorithm, int keySize, byte[] encodedPublicKeyPrefix)

Method Summary

Modifier and Type	Method	Description
javax.crypto.KeyAgreement	createKeyAgreement()
java.security.PublicKey	decode(byte[] key)
byte[]	encode(java.security.PublicKey key)
java.security.KeyPair	generateKeyPair()
java.lang.String	getAlgorithm()
int	getByteLength()	Retrieves the length of a point coordinate in bytes.
int	getKeySize()
boolean	isSupported()
static MontgomeryCurve	valueOf(java.lang.String name)	Returns the enum constant of this type with the specified name.
static MontgomeryCurve[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

x25519

public static final MontgomeryCurve x25519

X25519 uses Curve25519 and SHA-256 with a 32-byte key size.

x448

public static final MontgomeryCurve x448

X448 uses Curve448 and SHA-512 with a 56-byte key size.

Field Detail

algorithm

private final java.lang.String algorithm

keySize

private final int keySize

supported

private final boolean supported

keyPairGenerator

private final java.security.KeyPairGenerator keyPairGenerator

keyFactory

private final java.security.KeyFactory keyFactory

encodedPublicKeyPrefix

private final byte[] encodedPublicKeyPrefix

Constructor Detail

MontgomeryCurve

private MontgomeryCurve(java.lang.String algorithm,
                        int keySize,
                        byte[] encodedPublicKeyPrefix)

Method Detail

values

public static MontgomeryCurve[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (MontgomeryCurve c : MontgomeryCurve.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static MontgomeryCurve valueOf(java.lang.String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

java.lang.IllegalArgumentException - if this enum type has no constant with the specified name

java.lang.NullPointerException - if the argument is null

getAlgorithm

public java.lang.String getAlgorithm()

getByteLength

public int getByteLength()

Description copied from interface: CurveSizeIndicator

Retrieves the length of a point coordinate in bytes.

Specified by:

getByteLength in interface CurveSizeIndicator

Returns:

the length

getKeySize

public int getKeySize()

Specified by:

getKeySize in interface KeySizeIndicator

Returns:

The number of bits used in the key

isSupported

public boolean isSupported()

Specified by:

isSupported in interface OptionalFeature

createKeyAgreement

public javax.crypto.KeyAgreement createKeyAgreement()
                                             throws java.security.GeneralSecurityException

Throws:

java.security.GeneralSecurityException

generateKeyPair

public java.security.KeyPair generateKeyPair()

encode

public byte[] encode(java.security.PublicKey key)
              throws java.security.InvalidKeyException

Throws:

java.security.InvalidKeyException

decode

public java.security.PublicKey decode(byte[] key)
                               throws java.security.spec.InvalidKeySpecException

Throws:

java.security.spec.InvalidKeySpecException