java.security
Class SignatureSpi
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.
Object | clone() - Returns a clone if the implementation is cloneable.
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protected abstract Object | engineGetParameter(String param)
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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.
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protected abstract void | engineInitSign(PrivateKey privateKey) - Initializes this signature object with the specified private key for
signing operations.
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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.
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protected abstract void | engineInitVerify(PublicKey publicKey) - Initializes this signature object with the specified public key for
verification operations.
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protected abstract void | engineSetParameter(String param, Object value) - Replaced by engineSetParameter(AlgorithmParameterSpec).
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protected void | engineSetParameter(AlgorithmParameterSpec params) - This method is overridden by providers to initialize this signature engine
with the specified parameter set.
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protected abstract byte[] | engineSign() - Returns the signature bytes of all the data updated so far.
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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
.
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protected abstract void | engineUpdate(byte b) - Updates the data to be signed or verified using the specified byte.
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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.
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protected abstract boolean | engineVerify(byte[] sigBytes) - Verifies the passed-in signature.
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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.
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clone , equals , finalize , getClass , hashCode , notify , notifyAll , toString , wait , wait , wait |
SignatureSpi
public SignatureSpi()
The basic constructor. Object is special, because it has no
superclass, so there is no call to super().
engineGetParameter
protected abstract Object engineGetParameter(String param)
throws InvalidParameterException
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.
param
- the string name of the parameter.
- the object that represents the parameter value, or
null
if there is none.
InvalidParameterException
- if param
is an invalid
parameter for this engine, or another exception occurs while trying to get
this parameter.
engineGetParameters
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.
- the parameters used with this signature engine, or
null
if this signature engine does not use any parameters.
engineInitSign
protected abstract void engineInitSign(PrivateKey privateKey)
throws InvalidKeyException
Initializes this signature object with the specified private key for
signing operations.
privateKey
- the private key of the identity whose signature will be
generated.
engineInitSign
protected void engineInitSign(PrivateKey privateKey,
SecureRandom random)
throws InvalidKeyException
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.)
privateKey
- the private key of the identity whose signature will be
generated.random
- the source of randomness.
engineInitVerify
protected abstract void engineInitVerify(PublicKey publicKey)
throws InvalidKeyException
Initializes this signature object with the specified public key for
verification operations.
publicKey
- the public key of the identity whose signature is going
to be verified.
engineSetParameter
protected abstract void engineSetParameter(String param,
Object value)
throws InvalidParameterException
Replaced by engineSetParameter(AlgorithmParameterSpec).
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.
param
- the string identifier of the parameter.value
- the parameter value.
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.
engineSign
protected abstract byte[] engineSign()
throws SignatureException
Returns the signature bytes of all the data updated so far. The format of
the signature depends on the underlying signature scheme.
- the signature bytes of the signing operation's result.
engineSign
protected int engineSign(byte[] outbuf,
int offset,
int len)
throws SignatureException
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.
outbuf
- buffer for the signature result.offset
- offset into outbuf where the signature is stored.len
- number of bytes within outbuf allotted for the signature. Both
this default implementation and the GNU 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.
- the number of bytes placed into
outbuf
.
engineUpdate
protected abstract void engineUpdate(byte b)
throws SignatureException
Updates the data to be signed or verified using the specified byte.
b
- the byte to use for the update.
engineUpdate
protected abstract void engineUpdate(byte[] b,
int off,
int len)
throws SignatureException
Updates the data to be signed or verified, using the specified array of
bytes, starting at the specified offset.
b
- the array of bytes.off
- the offset to start from in the array of bytes.len
- the number of bytes to use, starting at offset.
engineVerify
protected abstract boolean engineVerify(byte[] sigBytes)
throws SignatureException
Verifies the passed-in signature.
sigBytes
- the signature bytes to be verified.
true
if the signature was verified, false
if not.
SignatureException
- if the engine is not initialized properly, or
the passed-in signature is improperly encoded or of the wrong type, etc.
engineVerify
protected boolean engineVerify(byte[] sigBytes,
int offset,
int length)
throws SignatureException
Verifies the passed-in
signature
in the specified array of
bytes, starting at the specified
offset
.
Note: Subclasses should overwrite the default implementation.
sigBytes
- the signature bytes to be verified.offset
- the offset to start from in the array of bytes.length
- the number of bytes to use, starting at offset.
true
if the signature was verified, false
if not.
SignatureException
- if the engine is not initialized properly, or
the passed-in signature
is improperly encoded or of the wrong
type, etc.
SignatureSpi.java --- Signature Service Provider Interface
Copyright (C) 1999, 2003, Free Software Foundation, Inc.
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