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SignatureSpi

public abstract class SignatureSpi
extends Object

java.lang.Object
   ↳ java.security.SignatureSpi
Known Direct Subclasses


This class defines the Service Provider Interface (SPI) for the Signature class, which is used to provide the functionality of a digital signature algorithm. Digital signatures are used for authentication and integrity assurance of digital data. .

All the abstract methods in this class must be implemented by each cryptographic service provider who wishes to supply the implementation of a particular signature algorithm.

See also:

Summary

Fields

protected SecureRandom appRandom

Application-specified source of randomness.

Public constructors

SignatureSpi()

Public methods

Object clone()

Returns a clone if the implementation is cloneable.

Protected methods

abstract Object engineGetParameter(String param)

This method was deprecated in API level 1. Deprecated.

AlgorithmParameters engineGetParameters()

This method is overridden by providers to return the parameters used with this signature engine, or null if this signature engine does not use any parameters.

void engineInitSign(PrivateKey privateKey, SecureRandom random)

Initializes this signature object with the specified private key and source of randomness for signing operations.

abstract void engineInitSign(PrivateKey privateKey)

Initializes this signature object with the specified private key for signing operations.

abstract void engineInitVerify(PublicKey publicKey)

Initializes this signature object with the specified public key for verification operations.

abstract void engineSetParameter(String param, Object value)

This method was deprecated in API level 1. Replaced by engineSetParameter.

void engineSetParameter(AlgorithmParameterSpec params)

This method is overridden by providers to initialize this signature engine with the specified parameter set.

abstract byte[] engineSign()

Returns the signature bytes of all the data updated so far.

int engineSign(byte[] outbuf, int offset, int len)

Finishes this signature operation and stores the resulting signature bytes in the provided buffer outbuf, starting at offset.

abstract void engineUpdate(byte[] b, int off, int len)

Updates the data to be signed or verified, using the specified array of bytes, starting at the specified offset.

void engineUpdate(ByteBuffer input)

Updates the data to be signed or verified using the specified ByteBuffer.

abstract void engineUpdate(byte b)

Updates the data to be signed or verified using the specified byte.

boolean engineVerify(byte[] sigBytes, int offset, int length)

Verifies the passed-in signature in the specified array of bytes, starting at the specified offset.

abstract boolean engineVerify(byte[] sigBytes)

Verifies the passed-in signature.

Inherited methods

From class java.lang.Object

Fields

appRandom

Added in API level 1
SecureRandom appRandom

Application-specified source of randomness.

Public constructors

SignatureSpi

Added in API level 1
SignatureSpi ()

Public methods

clone

Added in API level 1
Object clone ()

Returns a clone if the implementation is cloneable.

Returns
Object a clone if the implementation is cloneable.
Throws
CloneNotSupportedException if this is called on an implementation that does not support Cloneable.

Protected methods

engineGetParameter

Added in API level 1
Object engineGetParameter (String param)

This method was deprecated in API level 1.
Deprecated.

Gets the value of the specified algorithm parameter. This method supplies a general-purpose mechanism through which it is possible to get the various parameters of this object. A parameter may be any settable parameter for the algorithm, such as a parameter size, or a source of random bits for signature generation (if appropriate), or an indication of whether or not to perform a specific but optional computation. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

Parameters
param String: the string name of the parameter.
Returns
Object the object that represents the parameter value, or null if there is none.
Throws
InvalidParameterException if param is an invalid parameter for this engine, or another exception occurs while trying to get this parameter.

engineGetParameters

Added in API level 1
AlgorithmParameters engineGetParameters ()

This method is overridden by providers to return the parameters used with this signature engine, or null if this signature engine does not use any parameters.

The returned parameters may be the same that were used to initialize this signature engine, or may contain a combination of default and randomly generated parameter values used by the underlying signature implementation if this signature engine requires algorithm parameters but was not initialized with any.

Returns
AlgorithmParameters the parameters used with this signature engine, or null if this signature engine does not use any parameters
Throws
UnsupportedOperationException if this method is not overridden by a provider

engineInitSign

Added in API level 1
void engineInitSign (PrivateKey privateKey, 
                SecureRandom random)

Initializes this signature object with the specified private key and source of randomness for signing operations.

This concrete method has been added to this previously-defined abstract class. (For backwards compatibility, it cannot be abstract.)

Parameters
privateKey PrivateKey: the private key of the identity whose signature will be generated.
random SecureRandom: the source of randomness
Throws
InvalidKeyException if the key is improperly encoded, parameters are missing, and so on.

engineInitSign

Added in API level 1
void engineInitSign (PrivateKey privateKey)

Initializes this signature object with the specified private key for signing operations.

Parameters
privateKey PrivateKey: the private key of the identity whose signature will be generated.
Throws
InvalidKeyException if the key is improperly encoded, parameters are missing, and so on.

engineInitVerify

Added in API level 1
void engineInitVerify (PublicKey publicKey)

Initializes this signature object with the specified public key for verification operations.

Parameters
publicKey PublicKey: the public key of the identity whose signature is going to be verified.
Throws
InvalidKeyException if the key is improperly encoded, parameters are missing, and so on.

engineSetParameter

Added in API level 1
void engineSetParameter (String param, 
                Object value)

This method was deprecated in API level 1.
Replaced by engineSetParameter.

Sets the specified algorithm parameter to the specified value. This method supplies a general-purpose mechanism through which it is possible to set the various parameters of this object. A parameter may be any settable parameter for the algorithm, such as a parameter size, or a source of random bits for signature generation (if appropriate), or an indication of whether or not to perform a specific but optional computation. A uniform algorithm-specific naming scheme for each parameter is desirable but left unspecified at this time.

Parameters
param String: the string identifier of the parameter.
value Object: the parameter value.
Throws
InvalidParameterException if param is an invalid parameter for this signature algorithm engine, the parameter is already set and cannot be set again, a security exception occurs, and so on.

engineSetParameter

Added in API level 1
void engineSetParameter (AlgorithmParameterSpec params)

This method is overridden by providers to initialize this signature engine with the specified parameter set.

Parameters
params AlgorithmParameterSpec: the parameters
Throws
UnsupportedOperationException if this method is not overridden by a provider
InvalidAlgorithmParameterException if this method is overridden by a provider and the given parameters are inappropriate for this signature engine

engineSign

Added in API level 1
byte[] engineSign ()

Returns the signature bytes of all the data updated so far. The format of the signature depends on the underlying signature scheme.

Returns
byte[] the signature bytes of the signing operation's result.
Throws
SignatureException if the engine is not initialized properly or if this signature algorithm is unable to process the input data provided.

engineSign

Added in API level 1
int engineSign (byte[] outbuf, 
                int offset, 
                int len)

Finishes this signature operation and stores the resulting signature bytes in the provided buffer outbuf, starting at offset. The format of the signature depends on the underlying signature scheme.

The signature implementation is reset to its initial state (the state it was in after a call to one of the engineInitSign methods) and can be reused to generate further signatures with the same private key. This method should be abstract, but we leave it concrete for binary compatibility. Knowledgeable providers should override this method.

Parameters
outbuf byte: buffer for the signature result.
offset int: offset into outbuf where the signature is stored.
len int: number of bytes within outbuf allotted for the signature. Both this default implementation and the SUN provider do not return partial digests. If the value of this parameter is less than the actual signature length, this method will throw a SignatureException. This parameter is ignored if its value is greater than or equal to the actual signature length.
Returns
int the number of bytes placed into outbuf
Throws
SignatureException if the engine is not initialized properly, if this signature algorithm is unable to process the input data provided, or if len is less than the actual signature length.

engineUpdate

Added in API level 1
void engineUpdate (byte[] b, 
                int off, 
                int len)

Updates the data to be signed or verified, using the specified array of bytes, starting at the specified offset.

Parameters
b byte: the array of bytes
off int: the offset to start from in the array of bytes
len int: the number of bytes to use, starting at offset
Throws
SignatureException if the engine is not initialized properly

engineUpdate

Added in API level 1
void engineUpdate (ByteBuffer input)

Updates the data to be signed or verified using the specified ByteBuffer. Processes the data.remaining() bytes starting at at data.position(). Upon return, the buffer's position will be equal to its limit; its limit will not have changed.

Parameters
input ByteBuffer: the ByteBuffer

engineUpdate

Added in API level 1
void engineUpdate (byte b)

Updates the data to be signed or verified using the specified byte.

Parameters
b byte: the byte to use for the update.
Throws
SignatureException if the engine is not initialized properly.

engineVerify

Added in API level 1
boolean engineVerify (byte[] sigBytes, 
                int offset, 
                int length)

Verifies the passed-in signature in the specified array of bytes, starting at the specified offset.

Note: Subclasses should overwrite the default implementation.

Parameters
sigBytes byte: the signature bytes to be verified.
offset int: the offset to start from in the array of bytes.
length int: the number of bytes to use, starting at offset.
Returns
boolean true if the signature was verified, false if not.
Throws
SignatureException if the engine is not initialized properly, the passed-in signature is improperly encoded or of the wrong type, if this signature algorithm is unable to process the input data provided, etc.

engineVerify

Added in API level 1
boolean engineVerify (byte[] sigBytes)

Verifies the passed-in signature.

Parameters
sigBytes byte: the signature bytes to be verified.
Returns
boolean true if the signature was verified, false if not.
Throws
SignatureException if the engine is not initialized properly, the passed-in signature is improperly encoded or of the wrong type, if this signature algorithm is unable to process the input data provided, etc.
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