Added in API level 1

Summary: Fields | Ctors | Methods | Protected Methods | Inherited Methods

SignatureSpi

public abstract class SignatureSpi
extends Object

java.lang.Object
↳	java.security.SignatureSpi

Known direct subclasses

Signature

Signature The Signature class is used to provide applications the functionality of a digital signature algorithm.

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:

Signature

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 15. 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 15. 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

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Fields

appRandom

Added in API level 1

protected SecureRandom appRandom

Application-specified source of randomness.

Public constructors

SignatureSpi

Added in API level 1

public SignatureSpi ()

Public methods

clone

Added in API level 1

public 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
Deprecated in API level 15

protected abstract Object engineGetParameter (String param)

This method was deprecated in API level 15.
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

protected 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

protected 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

protected abstract 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

protected abstract 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
Deprecated in API level 15

protected abstract void engineSetParameter (String param, 
                Object value)

This method was deprecated in API level 15.
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

protected 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

protected abstract 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

protected 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

protected 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.

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

protected 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

protected abstract 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

protected 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

protected abstract 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.