iaik.security.ec.common

Class ECParameters

java.lang.Object

java.security.AlgorithmParametersSpi

iaik.security.ec.common.ECParameters

public final class ECParameters
extends AlgorithmParametersSpi

EC Parameters can be generated by calling one of the AlgorithmParameters.getInstance(String) methods. Subsequently the new AlgorithmParameters object must be initialized with a proper ECC parameter specification or a DER encoded byte array, e.g.:

 ECParameterSpec ecParamSpec = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("EC", "IAIK ECCelerate");
 params.init(ecParamSpec);
 

respectively:

 byte[] encodedECParams = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("EC", "IAIK ECCelerate");
 params.init(encodedECParams);
 

For obtaining EC parameters in transparent representation from an opaque ECParameterSpec object, the AlgorithmParameters.getParameterSpec(Class) method can be used; for obtaining the parameters as DER encoded ASN.1 object, use method AlgorithmParameters.getEncoded():

 ECParameterSpec ecParamSpec = (ECParameterSpec) params.getParameterSpec(ECParameterSpec.class);
 

respectively

 byte[] encodedECParams = params.getEncoded();
 

Author:

Christian Hanser

See Also:

ECParameterSpec, ECStandardizedParameterFactory, AlgorithmParameters

Constructor Summary

Constructors

Constructor and Description
ECParameters() Default constructor.

Method Summary

Modifier and Type	Method and Description
protected byte[]	engineGetEncoded() Returns the parameters as DER byte array.
protected byte[]	engineGetEncoded(String format) Returns the parameters as a DER byte array.
protected <T extends AlgorithmParameterSpec> T	engineGetParameterSpec(Class<T> paramSpec) Returns the EC parameters as transparent parameter specification of the given class type.
protected void	engineInit(AlgorithmParameterSpec paramSpec) Initializes this ECAlgorithmParameters from the given ECParameterSpec.
protected void	engineInit(byte[] params) Initializes this ECParameters object from the given DER encoded byte array.
protected void	engineInit(byte[] params, String format) Inits the parameters from an DER encoded byte array.
protected String	engineToString() Returns a String representation of this object.
static void	setSetCurveNameForECGenParameterSpec(boolean setName) Decides whether to set the curve name (instead of the OID String) for the ECGenParameterSpec returned when calling ecParameters.getParameterSpec(ECGenParameterSpec.class);.
iaik.asn1.ASN1Object	toASN1Object() Gets an ASN.1 representation of this ECC algorithm parameters.

Methods inherited from class java.lang.Object

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

Constructor Detail

ECParameters

public ECParameters()

Default constructor.

Method Detail

setSetCurveNameForECGenParameterSpec

public static void setSetCurveNameForECGenParameterSpec(boolean setName)

Decides whether to set the curve name (instead of the OID String) for the ECGenParameterSpec returned when calling ecParameters.getParameterSpec(ECGenParameterSpec.class);.

When creating an ECGenParameterSpec from ECParameters the ECGenParameterSpec either may contain the standard name or the OID String of the curve the parameters belong to. Up to version 6.01 ECCelerate tried to generate an ECGenParameterSpec containing the curve name (if available). However, since JSSE expects that the ECGenParameterSpec does contain the OID String (rather than the curve name) method engineGetParameterSpec(Class) engineGetParameterSpec(ECGenParameterSpec.class) now returns an ECGenParameterSpec with the OID String. Otherwise the handshake may fail (JDK 11.0.7) or ecdsa_sha1 may be used instead of ecdsa_secp256r1_sha256, ecdsa_secp384r1_sha384 or ecdsa_secp521r1_sha512. If you want to get an ECGenParameterSpec containing the curve name you may call setSetCurveNameForECGenParameterSpec(true);:

 ECParameters.setSetCurveNameForECGenParameterSpec(true);
 ...
 ECParameterSpec ecParamSpec = ...;
 AlgorithmParameters ecParams = AlgorithmParameters.getInstance("EC");
 parameters.init(ecParamSpec);
 ECGenParameterSpec ecGenSpec = .getParameterSpec(ECGenParameterSpec.class);
 String curveName = ecGenSpec.getName();
 

Alternatively (if there is no need for provide independence) you may use the

 ECParameterSpec ecParamSpec = ...;
 String curveName = ECStandardizedParameterFactory.getName(ecParamSpec); 
 

Parameters:

setName - whether engineGetParameterSpec(Class) shall return an ECGenParameterSpec with the curve name or the curve oid string (default)

engineInit

protected void engineInit(AlgorithmParameterSpec paramSpec)
                   throws InvalidParameterSpecException

Initializes this ECAlgorithmParameters from the given ECParameterSpec.

Specified by:

engineInit in class AlgorithmParametersSpi

Parameters:

paramSpec - the parameter specification, which has to be a ECParameterSpec

Throws:

InvalidParameterSpecException - if the given parameter specification is not a or is an invalid ECParameterSpec

engineInit

protected void engineInit(byte[] params)
                   throws IOException

Initializes this ECParameters object from the given DER encoded byte array.

Specified by:

engineInit in class AlgorithmParametersSpi

Parameters:

params - the DER encoded byte array

Throws:

IOException - if an error occurs when decoding the given byte array

engineInit

protected void engineInit(byte[] params,
                          String format)
                   throws IOException

Inits the parameters from an DER encoded byte array. Format is ignored. Only calls engineInit(byte[]) for initializing this ECCAlgorithmParameters object from the given DER encoded byte array, regardless of what is specified in the format string.

Specified by:

engineInit in class AlgorithmParametersSpi

Parameters:

params - the DER encoded byte array

format - the encoding format; ignored

Throws:

IOException - if an error occurs when decoding the given byte array

engineGetParameterSpec

protected <T extends AlgorithmParameterSpec> T engineGetParameterSpec(Class<T> paramSpec)
                                                               throws InvalidParameterSpecException

Returns the EC parameters as transparent parameter specification of the given class type.

Specified by:

engineGetParameterSpec in class AlgorithmParametersSpi

Parameters:

paramSpec - the desired parameter specification class (ECParameterSpec )

Returns:

the parameters as ECParameterSpec

Throws:

InvalidParameterSpecException - if the parameters cannot be converted to the desired parameter specification

engineGetEncoded

protected byte[] engineGetEncoded()
                           throws IOException

Returns the parameters as DER byte array.

Specified by:

engineGetEncoded in class AlgorithmParametersSpi

Returns:

the DER encoded parameters

Throws:

IOException - if an encoding error occurs

engineGetEncoded

protected byte[] engineGetEncoded(String format)
                           throws IOException

Returns the parameters as a DER byte array.

Format is ignored. Only DER encoding is supported. This method only calls engineGetEncoded(), regardless of what is specified in the format string.

Specified by:

engineGetEncoded in class AlgorithmParametersSpi

Parameters:

format - the encoding format; ignored

Returns:

the DER encoded parameters

Throws:

IOException - if an encoding error occurs

engineToString

protected String engineToString()

Returns a String representation of this object.

Specified by:

engineToString in class AlgorithmParametersSpi

Returns:

a String representation this object

toASN1Object

public iaik.asn1.ASN1Object toASN1Object()

Gets an ASN.1 representation of this ECC algorithm parameters.

Returns:

this ECC algorithm parameters as ASN1Object