iaik.security.cipher

Class OCBParameters

java.lang.Object

java.security.AlgorithmParametersSpi

iaik.security.cipher.OCBParameters

public class OCBParameters
extends java.security.AlgorithmParametersSpi

This class represents OCB parameters.

(RFC 7253) does not provide an ASN.1 specification for OCB parameters. This implementation interprets OCB ASN.1 parameters similarly to that used for GCM as ASN.1 SEQUENCE of nonce value and tag length:

 OCBParameters ::= SEQUENCE {
       nonce        OCTET STRING, -- recommended size is 12 octets
       tagLen       OCB-TAGlen DEFAULT 16 }

 OCB-TAGlen ::= INTEGER (1..16) 
 

The tagLen component specifies the length (in number of bytes; default 16) of the message authentication code value.

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

 OCBParameterSpec ocbParamSpec = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("OCB", "IAIK");
 params.init(ocbParamsSpec);
 

or

 byte[] encodedParams = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("OCB", "IAIK");
 params.init(encodedParams);
 OCBParameterSpec ocbParamSpec = (OCBParameterSpec)params.getParameterSpec(OCBParameterSpec.class);
 

Version:

File Revision 4

See Also:

OCBParameterSpec

Constructor Summary

Constructors

Constructor and Description
OCBParameters() The default constructor.
OCBParameters(OCBParameterSpec paramSpec) Creates OCB Parameters from the given parameter specification.

Method Summary

Modifier and Type	Method and Description
static void	checkKeyAndNonceReuse(boolean check) Dis/Enables check for key/nonce reuse.
protected byte[]	engineGetEncoded() Gets 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 OCB Parameter Specification of this OCB Parameters object.
protected void	engineInit(java.security.spec.AlgorithmParameterSpec paramSpec) Initializes this AlgorithmParameters object with the given parameter specification.
protected void	engineInit(byte[] params) Initializes this OCBParameters 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 OCB Parameters.
static void	setIncludeDefaultTagLengthInEncding(boolean include) Decides whether the tagLen component should be included when encoding OCB parameters if it has the default value (16).

Methods inherited from class java.lang.Object

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

Constructor Detail

OCBParameters

public OCBParameters()

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

OCBParameters

public OCBParameters(OCBParameterSpec paramSpec)

Creates OCB Parameters from the given parameter specification.

Parameters:

paramSpec - the OCBParamaterSpec

Method Detail

setIncludeDefaultTagLengthInEncding

public static void setIncludeDefaultTagLengthInEncding(boolean include)

Decides whether the tagLen component should be included when encoding OCB parameters if it has the default value (16). Although default values should be not included (if DER is used) it might be required to include the default value for compatibility reasons (when BER is used).

Parameters:

include - whether to include a default tagLen value (16) when encoding OCB parameters or not (by default the default value is not included)

checkKeyAndNonceReuse

public static void checkKeyAndNonceReuse(boolean check)

Dis/Enables check for key/nonce reuse.

OCB shall not be used with same key and nonce multiple times. We cannot check any key/nonce pair that may have been used in the past, but we can check if a Cipher has been reinitialized before used for encryption a second time. This means we only check if Cipher.init() has been called before any further Cipher.update() or Cipher.doFinal() after an encryption operation has been finished; we do not check if an Cipher.init() call has actually provided a new key/nonce combination.

Parameters:

check - true to enable key/nonce reuse check (default), false to disable it

engineGetEncoded

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

Gets the parameters as DER byte array.

Specified by:

engineGetEncoded in class java.security.AlgorithmParametersSpi

Returns:

the OCB 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 OCB 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 OCB Parameter Specification of this OCB Parameters object. paramSpec identifies the specification class in which the parameters should be returned, which might be iaik.security.cipher.OCBParameterSpec.

Specified by:

engineGetParameterSpec in class java.security.AlgorithmParametersSpi

Parameters:

paramSpec - the specification class in which the parameters should be returned (iaik.security.cipher.OCBParameterSpec)

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 AlgorithmParameters object with the given parameter specification.

Specified by:

engineInit in class java.security.AlgorithmParametersSpi

Parameters:

paramSpec - the parameter specification - must be OCBParameterSpec.

Throws:

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

engineInit

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

Initializes this OCBParameters 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 OCBParameters 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 OCB Parameters.

Specified by:

engineToString in class java.security.AlgorithmParametersSpi

Returns:

a formatted string describing the OCB Parameters.