- Direct Known Subclasses:
Signature
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.
- Since:
- 1.2
- See Also:
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Field Summary
Modifier and TypeFieldDescriptionprotected SecureRandom
Application-specified source of randomness. -
Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionclone()
Returns a clone if the implementation is cloneable.protected abstract Object
engineGetParameter
(String param) Deprecated.protected AlgorithmParameters
Returns the parameters used with thisSignature
object.protected abstract void
engineInitSign
(PrivateKey privateKey) Initializes thisSignature
object with the specified private key for signing operations.protected void
engineInitSign
(PrivateKey privateKey, SecureRandom random) Initializes thisSignature
object with the specified private key and source of randomness for signing operations.protected abstract void
engineInitVerify
(PublicKey publicKey) Initializes thisSignature
object with the specified public key for verification operations.protected abstract void
engineSetParameter
(String param, Object value) Deprecated.protected void
Initializes thisSignature
object with the specified parameter values.protected abstract byte[]
Returns the signature bytes of all the data updated so far.protected int
engineSign
(byte[] outbuf, int offset, int len) Finishes this signature operation and stores the resulting signature bytes in the provided bufferoutbuf
, starting atoffset
.protected abstract void
engineUpdate
(byte b) Updates the data to be signed or verified using the specified byte.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.protected void
engineUpdate
(ByteBuffer input) Updates the data to be signed or verified using the specified ByteBuffer.protected abstract boolean
engineVerify
(byte[] sigBytes) Verifies the passed-in signature.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.
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Field Details
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appRandom
Application-specified source of randomness.
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Constructor Details
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SignatureSpi
public SignatureSpi()Constructor for subclasses to call.
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Method Details
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engineInitVerify
Initializes thisSignature
object with the specified public key for verification operations.- Parameters:
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.
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engineInitSign
Initializes thisSignature
object with the specified private key for signing operations.- Parameters:
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.
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engineInitSign
protected void engineInitSign(PrivateKey privateKey, SecureRandom random) throws InvalidKeyException Initializes thisSignature
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
- the private key of the identity whose signature will be generated.random
- the source of randomness- Throws:
InvalidKeyException
- if the key is improperly encoded, parameters are missing, and so on.
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engineUpdate
Updates the data to be signed or verified using the specified byte.- Parameters:
b
- the byte to use for the update.- Throws:
SignatureException
- if the engine is not initialized properly.
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engineUpdate
Updates the data to be signed or verified, using the specified array of bytes, starting at the specified offset.- Parameters:
b
- the array of bytesoff
- the offset to start from in the array of byteslen
- the number of bytes to use, starting at offset- Throws:
SignatureException
- if the engine is not initialized properly
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engineUpdate
Updates the data to be signed or verified using the specified ByteBuffer. Processes thedata.remaining()
bytes starting atdata.position()
. Upon return, the buffer's position will be equal to its limit; its limit will not have changed.- Parameters:
input
- the ByteBuffer- Since:
- 1.5
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engineSign
Returns the signature bytes of all the data updated so far. The format of the signature depends on the underlying signature scheme.- Returns:
- 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.
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engineSign
Finishes this signature operation and stores the resulting signature bytes in the provided bufferoutbuf
, starting atoffset
. 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
- buffer for the signature result.offset
- offset intooutbuf
where the signature is stored.len
- number of bytes withinoutbuf
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 aSignatureException
. This parameter is ignored if its value is greater than or equal to the actual signature length.- Returns:
- 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 iflen
is less than the actual signature length.- Since:
- 1.2
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engineVerify
Verifies the passed-in signature.- Parameters:
sigBytes
- the signature bytes to be verified.- Returns:
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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engineVerify
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
- 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.- Returns:
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.- Since:
- 1.4
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engineSetParameter
@Deprecated protected abstract void engineSetParameter(String param, Object value) throws InvalidParameterException Deprecated.Replaced byengineSetParameter
.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 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
- the string identifier of the parameter.value
- the parameter value.- Throws:
InvalidParameterException
- ifparam
is an invalid parameter for thisSignature
object, the parameter is already set and cannot be set again, a security exception occurs, and so on.
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engineSetParameter
protected void engineSetParameter(AlgorithmParameterSpec params) throws InvalidAlgorithmParameterException Initializes thisSignature
object with the specified parameter values.- Parameters:
params
- the parameters- Throws:
UnsupportedOperationException
- if this method is not overridden by a providerInvalidAlgorithmParameterException
- if this method is overridden by a provider and the given parameters are inappropriate for thisSignature
object
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engineGetParameters
Returns the parameters used with thisSignature
object.The returned parameters may be the same that were used to initialize this
Signature
object, or may contain additional default or random parameter values used by the underlying signature scheme. If the required parameters were not supplied and can be generated by theSignature
object, the generated parameters are returned; otherwisenull
is returned.However, if the signature scheme does not support returning the parameters as
AlgorithmParameters
,null
is always returned.- Returns:
- the parameters used with this
Signature
object, ornull
- Throws:
UnsupportedOperationException
- if this method is not overridden by a provider- Since:
- 1.4
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engineGetParameter
@Deprecated protected abstract Object engineGetParameter(String param) throws InvalidParameterException 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 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
- the string name of the parameter.- Returns:
- the object that represents the parameter value, or
null
if there is none. - Throws:
InvalidParameterException
- ifparam
is an invalid parameter for this engine, or another exception occurs while trying to get this parameter.
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clone
Returns a clone if the implementation is cloneable.- Overrides:
clone
in classObject
- Returns:
- a clone if the implementation is cloneable.
- Throws:
CloneNotSupportedException
- if this is called on an implementation that does not supportCloneable
.- See Also:
-
engineSetParameter
.