java.lang.Object | ||
↳ | java.security.SignatureSpi | |
↳ | java.security.Signature |
This Signature class is used to provide applications the functionality of a digital signature algorithm. Digital signatures are used for authentication and integrity assurance of digital data.
The signature algorithm can be, among others, the NIST standard DSA, using DSA and SHA-1. The DSA algorithm using the SHA-1 message digest algorithm can be specified as SHA1withDSA. In the case of RSA, there are multiple choices for the message digest algorithm, so the signing algorithm could be specified as, for example, MD2withRSA, MD5withRSA, or SHA1withRSA. The algorithm name must be specified, as there is no default.
A Signature object can be used to generate and verify digital signatures.
There are three phases to the use of a Signature object for either signing data or verifying a signature:
initVerify
), or
initSign(PrivateKey)
and initSign(PrivateKey, SecureRandom)
).
Depending on the type of initialization, this will update the
bytes to be signed or verified. See the
update
methods.
sign
methods and the verify
method.
Note that this class is abstract and extends from
SignatureSpi
for historical reasons.
Application developers should only take notice of the methods defined in
this Signature
class; all the methods in
the superclass are intended for cryptographic service providers who wish to
supply their own implementations of digital signature algorithms.
Constants | |||||||||||
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int | SIGN | Possible state value, signifying that
this signature object has been initialized for signing. |
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int | UNINITIALIZED | Possible state value, signifying that
this signature object has not yet been initialized. |
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int | VERIFY | Possible state value, signifying that
this signature object has been initialized for verification. |
Fields | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
state | Current state of this signature object. |
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Inherited Fields | |||||||||||
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From class
java.security.SignatureSpi
|
Protected Constructors | |||||||||||
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Creates a Signature object for the specified algorithm.
|
Public Methods | |||||||||||
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Returns a clone if the implementation is cloneable.
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Returns the name of the algorithm for this signature object.
| |||||||||||
Returns a Signature object that implements the specified signature
algorithm.
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Returns a Signature object that implements the specified
signature algorithm.
| |||||||||||
Returns a Signature object that implements the specified signature
algorithm.
| |||||||||||
This method is deprecated.
No replacement.
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Returns the parameters used with this signature object.
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Returns the provider of this signature object.
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Initialize this object for signing.
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Initialize this object for signing.
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Initializes this object for verification, using the public key from
the given certificate.
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Initializes this object for verification.
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This method is deprecated.
Use
setParameter .
| |||||||||||
Initializes this signature engine with the specified parameter set.
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Returns the signature bytes of all the data updated.
| |||||||||||
Finishes the signature operation and stores the resulting signature
bytes in the provided buffer
outbuf , starting at
offset . | |||||||||||
Returns a string representation of this signature object,
providing information that includes the state of the object
and the name of the algorithm used.
| |||||||||||
Updates the data to be signed or verified using the specified
ByteBuffer.
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Updates the data to be signed or verified, using the specified
array of bytes, starting at the specified offset.
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Updates the data to be signed or verified by a byte.
| |||||||||||
Updates the data to be signed or verified, using the specified
array of bytes.
| |||||||||||
Verifies the passed-in signature.
| |||||||||||
Verifies the passed-in signature in the specified array
of bytes, starting at the specified offset.
|
[Expand]
Inherited Methods | |||||||||||
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From class
java.security.SignatureSpi
| |||||||||||
From class
java.lang.Object
|
Possible state
value, signifying that
this signature object has been initialized for signing.
Possible state
value, signifying that
this signature object has not yet been initialized.
Possible state
value, signifying that
this signature object has been initialized for verification.
Current state of this signature object.
Creates a Signature object for the specified algorithm.
algorithm | the standard string name of the algorithm. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names. |
---|
Returns a clone if the implementation is cloneable.
CloneNotSupportedException | if this is called
on an implementation that does not support Cloneable .
|
---|
Returns the name of the algorithm for this signature object.
Returns a Signature object that implements the specified signature algorithm.
A new Signature object encapsulating the SignatureSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.
Note that the list of registered providers may be retrieved via
the Security.getProviders()
method.
algorithm | the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names. |
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provider | the name of the provider. |
NoSuchAlgorithmException | if a SignatureSpi implementation for the specified algorithm is not available from the specified provider. |
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NoSuchProviderException | if the specified provider is not registered in the security provider list. |
IllegalArgumentException | if the provider name is null or empty. |
Returns a Signature object that implements the specified signature algorithm.
A new Signature object encapsulating the SignatureSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
algorithm | the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names. |
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provider | the provider. |
NoSuchAlgorithmException | if a SignatureSpi implementation for the specified algorithm is not available from the specified Provider object. |
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IllegalArgumentException | if the provider is null. |
Returns a Signature object that implements the specified signature algorithm.
This method traverses the list of registered security Providers, starting with the most preferred Provider. A new Signature object encapsulating the SignatureSpi implementation from the first Provider that supports the specified algorithm is returned.
Note that the list of registered providers may be retrieved via
the Security.getProviders()
method.
algorithm | the standard name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names. |
---|
NoSuchAlgorithmException | if no Provider supports a Signature implementation for the specified algorithm. |
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This method is deprecated.
No replacement.
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. |
---|
InvalidParameterException | if param is an invalid
parameter for this engine, or another exception occurs while
trying to get this parameter. |
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Returns the parameters used with this signature object.
The returned parameters may be the same that were used to initialize this signature, or may contain a combination of default and randomly generated parameter values used by the underlying signature implementation if this signature requires algorithm parameters but was not initialized with any.
Returns the provider of this signature object.
Initialize this object for signing. If this method is called again with a different argument, it negates the effect of this call.
privateKey | the private key of the identity whose signature is going to be generated. |
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InvalidKeyException | if the key is invalid. |
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Initialize this object for signing. If this method is called again with a different argument, it negates the effect of this call.
privateKey | the private key of the identity whose signature is going to be generated. |
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random | the source of randomness for this signature. |
InvalidKeyException | if the key is invalid. |
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Initializes this object for verification, using the public key from the given certificate.
If the certificate is of type X.509 and has a key usage
extension field marked as critical, and the value of the key usage
extension field implies that the public key in
the certificate and its corresponding private key are not
supposed to be used for digital signatures, an
InvalidKeyException
is thrown.
certificate | the certificate of the identity whose signature is going to be verified. |
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InvalidKeyException | if the public key in the certificate is not encoded properly or does not include required parameter information or cannot be used for digital signature purposes. |
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Initializes this object for verification. If this method is called again with a different argument, it negates the effect of this call.
publicKey | the public key of the identity whose signature is going to be verified. |
---|
InvalidKeyException | if the key is invalid. |
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This method is deprecated.
Use
setParameter
.
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. |
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Initializes this signature engine with the specified parameter set.
params | the parameters |
---|
InvalidAlgorithmParameterException | if the given parameters are inappropriate for this signature engine |
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Returns the signature bytes of all the data updated. The format of the signature depends on the underlying signature scheme.
A call to this method resets this signature object to the state
it was in when previously initialized for signing via a
call to initSign(PrivateKey)
. That is, the object is
reset and available to generate another signature from the same
signer, if desired, via new calls to update
and
sign
.
SignatureException | if this signature object is not initialized properly or if this signature algorithm is unable to process the input data provided. |
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Finishes the 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.
This signature object is reset to its initial state (the state it
was in after a call to one of the initSign
methods) and
can be reused to generate further signatures with the same private key.
outbuf | buffer for the signature result. |
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offset | offset into outbuf where the signature is
stored. |
len | number of bytes within outbuf allotted for the
signature. |
outbuf
.SignatureException | if this signature object 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. |
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Returns a string representation of this signature object, providing information that includes the state of the object and the name of the algorithm used.
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.
data | the ByteBuffer |
---|
SignatureException | if this signature object is not initialized properly. |
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Updates the data to be signed or verified, using the specified array of bytes, starting at the specified offset.
data | the array of bytes. |
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off | the offset to start from in the array of bytes. |
len | the number of bytes to use, starting at offset. |
SignatureException | if this signature object is not initialized properly. |
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Updates the data to be signed or verified by a byte.
b | the byte to use for the update. |
---|
SignatureException | if this signature object is not initialized properly. |
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Updates the data to be signed or verified, using the specified array of bytes.
data | the byte array to use for the update. |
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SignatureException | if this signature object is not initialized properly. |
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Verifies the passed-in signature.
A call to this method resets this signature object to the state
it was in when previously initialized for verification via a
call to initVerify(PublicKey)
. That is, the object is
reset and available to verify another signature from the identity
whose public key was specified in the call to initVerify
.
signature | the signature bytes to be verified. |
---|
SignatureException | if this signature object 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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Verifies the passed-in signature in the specified array of bytes, starting at the specified offset.
A call to this method resets this signature object to the state
it was in when previously initialized for verification via a
call to initVerify(PublicKey)
. That is, the object is
reset and available to verify another signature from the identity
whose public key was specified in the call to initVerify
.
signature | the signature bytes to be verified. |
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offset | the offset to start from in the array of bytes. |
length | the number of bytes to use, starting at offset. |
SignatureException | if this signature object 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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IllegalArgumentException | if the signature
byte array is null, or the offset or length
is less than 0, or the sum of the offset and
length is greater than the length of the
signature byte array. |