iaik.security.cipher

Class GCMParameters

java.lang.Object

java.security.AlgorithmParametersSpi

iaik.security.cipher.GCMParameters

public class GCMParameters
extends java.security.AlgorithmParametersSpi

This class represents GCM parameters. The parameters specified for the GCM algorithm in RFC 5084 consist of the nonce and the length of the MAC (ICVlen):

 GCMParameters ::= SEQUENCE {
       aes-nonce        OCTET STRING, -- recommended size is 12 octets
       aes-ICVlen       AES-GCM-ICVlen DEFAULT 12 }

 AES-GCM-ICVlen ::= INTEGER (12 | 13 | 14 | 15 | 16)
 

As stated in the NIST Special Publication 800-38D also the MAC length of 4 and 8 bytes are possible. Additionally, this class holds the GCM parameter associated data and MAC block.

GCMParameters can be generated by calling one of the AlgorithmParameters.getInstance methods. Subsequently, the new AlgorithmParameters object must be initialized with a proper parameter specification (class GCMParameterSpec is recommended) or a DER encoded byte array, e.g.

 GCMParameterSpec gcmParamSpec = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("GCM", "IAIK");
 params.init(gcmParamsSpec);
 

The GCMParameters can also be initialized with an IvParameterSpec object. In this case, the specified IV will be used as nonce.

Version:

File Revision 4

See Also:

GCMParameterSpec, AlgorithmParametersSpi

Constructor Summary

Constructors

Constructor and Description
GCMParameters() The default constructor.
GCMParameters(byte[] aad, byte[] nonce, byte[] macBlock, int macLength) Creates GCM Parameters with the given additional data, IV, MAC length and MAC block.

Method Summary

Methods

Modifier and Type	Method and Description
protected byte[]	engineGetEncoded() Returns the parameters as DER byte array.
protected byte[]	engineGetEncoded(java.lang.String format) Returns the parameters as a DER byte array.
protected java.security.spec.AlgorithmParameterSpec	engineGetParameterSpec(java.lang.Class paramSpec) Returns a GCM Parameter Specification of this GCM Parameters object.
protected void	engineInit(java.security.spec.AlgorithmParameterSpec paramSpec) Initializes this parameters object using the parameters specified in paramSpec.
protected void	engineInit(byte[] params) Initializes this GCMParameters object from the given DER encoded byte array.
protected void	engineInit(byte[] params, java.lang.String format) Inits the parameters from an DER encoded byte array.
protected java.lang.String	engineToString() Returns a formatted string describing the GCM Parameters.

Methods inherited from class java.lang.Object

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

Constructor Detail

GCMParameters

public GCMParameters()
              throws java.security.InvalidAlgorithmParameterException

The default constructor. No values are set for the parameters. Use AlgorithmParameters.getInstance for obtaining a GCMParameters object.

Throws:

java.security.InvalidAlgorithmParameterException - if the parameter values are incorrect

GCMParameters

public GCMParameters(byte[] aad,
             byte[] nonce,
             byte[] macBlock,
             int macLength)
              throws java.security.InvalidAlgorithmParameterException

Creates GCM Parameters with the given additional data, IV, MAC length and MAC block.

Parameters:

aad - the additional data that is authenticated

nonce - the nonce to generate the IV

macLength - number of bytes used for authentication

macBlock - the authentication block

Throws:

java.security.InvalidAlgorithmParameterException - if the parameter values are incorrect

Method Detail

engineGetEncoded

protected byte[] engineGetEncoded()
                           throws java.io.IOException

Returns the parameters as DER byte array.

Specified by:

engineGetEncoded in class java.security.AlgorithmParametersSpi

Returns:

the GCM parameters as DER byte array

Throws:

java.io.IOException - if an encoding error occurs

engineGetEncoded

protected byte[] engineGetEncoded(java.lang.String format)
                           throws java.io.IOException

Returns the parameters as a DER byte array.

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

Specified by:

engineGetEncoded in class java.security.AlgorithmParametersSpi

Parameters:

format - the encoding format; ignored

Returns:

the GCM parameters as DER byte array

Throws:

java.io.IOException - if an encoding error occurs

engineGetParameterSpec

protected java.security.spec.AlgorithmParameterSpec engineGetParameterSpec(java.lang.Class paramSpec)
                                                                    throws java.security.spec.InvalidParameterSpecException

Returns a GCM Parameter Specification of this GCM Parameters object. paramSpec identifies the specification class in which the parameters should be returned. If paramSpec is not GCMParameterSpec than a InvalidParameterSpecException is thrown.

Specified by:

engineGetParameterSpec in class java.security.AlgorithmParametersSpi

Parameters:

paramSpec - the specification class in which the parameters should be returned - has to be the class GCMParameterSpec

Returns:

the parameter specification.

Throws:

java.security.spec.InvalidParameterSpecException - if the requested parameter specification is inappropriate for this parameter object.

engineInit

protected void engineInit(java.security.spec.AlgorithmParameterSpec paramSpec)
                   throws java.security.spec.InvalidParameterSpecException

Initializes this parameters object using the parameters specified in paramSpec.

Specified by:

engineInit in class java.security.AlgorithmParametersSpi

Parameters:

paramSpec - the parameter specification - must be GCMParameterSpec.

Throws:

java.security.spec.InvalidParameterSpecException - if the given parameter specification is inappropriate for the initialization of this parameter object.

engineInit

protected void engineInit(byte[] params)
                   throws java.io.IOException

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

Specified by:

engineInit in class java.security.AlgorithmParametersSpi

Parameters:

params - the DER encoded byte array

Throws:

java.io.IOException - if an error occurs when decoding the given byte array or the derived parameter values are invalid

engineInit

protected void engineInit(byte[] params,
              java.lang.String format)
                   throws java.io.IOException

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

Specified by:

engineInit in class java.security.AlgorithmParametersSpi

Parameters:

params - the DER encoded byte array

format - the encoding format; ignored

Throws:

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

engineToString

protected java.lang.String engineToString()

Returns a formatted string describing the GCM Parameters.

Specified by:

engineToString in class java.security.AlgorithmParametersSpi

Returns:

a formatted string describing the GCM Parameters.