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:
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 |
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 |
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 ()
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.
|
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. |
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 |
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. |
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. |
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. |
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. |
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 |
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. |
Developers
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. |
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 |
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 |
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. |
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. |
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. |