Signature
public abstract class SignatureSpi extends Object
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.
Modifier and Type | Field | Description |
---|---|---|
protected SecureRandom |
appRandom |
Application-specified source of randomness. |
Constructor | Description |
---|---|
SignatureSpi() |
Constructor for subclasses to call. |
Modifier and Type | Method | Description |
---|---|---|
Object |
clone() |
Returns a clone if the implementation is cloneable. |
protected abstract Object |
engineGetParameter |
Deprecated. |
protected AlgorithmParameters |
engineGetParameters() |
Returns the parameters used with this Signature object. |
protected abstract void |
engineInitSign |
Initializes this Signature object with the specified private key for signing operations. |
protected void |
engineInitSign |
Initializes this Signature object with the specified private key and source of randomness for signing operations. |
protected abstract void |
engineInitVerify |
Initializes this Signature object with the specified public key for verification operations. |
protected abstract void |
engineSetParameter |
Deprecated. |
protected void |
engineSetParameter |
Initializes this Signature object with the specified parameter values. |
protected abstract byte[] |
engineSign() |
Returns the signature bytes of all the data updated so far. |
protected int |
engineSign |
Finishes this signature operation and stores the resulting signature bytes in the provided buffer outbuf , starting at offset . |
protected abstract void |
engineUpdate |
Updates the data to be signed or verified using the specified byte. |
protected abstract void |
engineUpdate |
Updates the data to be signed or verified, using the specified array of bytes, starting at the specified offset. |
protected void |
engineUpdate |
Updates the data to be signed or verified using the specified ByteBuffer. |
protected abstract boolean |
engineVerify |
Verifies the passed-in signature. |
protected boolean |
engineVerify |
Verifies the passed-in signature in the specified array of bytes, starting at the specified offset. |
protected SecureRandom appRandom
public SignatureSpi()
protected abstract void engineInitVerify(PublicKey publicKey) throws InvalidKeyException
Signature
object with the specified public key for verification operations.publicKey
- the public key of the identity whose signature is going to be verified.InvalidKeyException
- if the key is improperly encoded, parameters are missing, and so on.protected abstract void engineInitSign(PrivateKey privateKey) throws InvalidKeyException
Signature
object with the specified private key for signing operations.privateKey
- the private key of the identity whose signature will be generated.InvalidKeyException
- if the key is improperly encoded, parameters are missing, and so on.protected void engineInitSign(PrivateKey privateKey, SecureRandom random) throws InvalidKeyException
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 randomnessInvalidKeyException
- if the key is improperly encoded, parameters are missing, and so on.protected abstract void engineUpdate(byte b) throws SignatureException
b
- the byte to use for the update.SignatureException
- if the engine is not initialized properly.protected abstract void engineUpdate(byte[] b, int off, int len) throws SignatureException
b
- the array of bytesoff
- the offset to start from in the array of byteslen
- the number of bytes to use, starting at offsetSignatureException
- if the engine is not initialized properlyprotected void engineUpdate(ByteBuffer input)
data.remaining()
bytes starting at data.position()
. Upon return, the buffer's position will be equal to its limit; its limit will not have changed.input
- the ByteBufferprotected abstract byte[] engineSign() throws SignatureException
SignatureException
- if the engine is not initialized properly or if this signature algorithm is unable to process the input data provided.protected int engineSign(byte[] outbuf, int offset, int len) throws SignatureException
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 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.outbuf
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.protected abstract boolean engineVerify(byte[] sigBytes) throws SignatureException
sigBytes
- the signature bytes to be verified.true
if the signature was verified, false
if not.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.protected boolean engineVerify(byte[] sigBytes, int offset, int length) throws SignatureException
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, 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.@Deprecated protected abstract void engineSetParameter(String param, Object value) throws InvalidParameterException
engineSetParameter
.param
- the string identifier of the parameter.value
- the parameter value.InvalidParameterException
- if param
is an invalid parameter for this Signature
object, the parameter is already set and cannot be set again, a security exception occurs, and so on.protected void engineSetParameter(AlgorithmParameterSpec params) throws InvalidAlgorithmParameterException
Signature
object with the specified parameter values.params
- the parametersUnsupportedOperationException
- if this method is not overridden by a providerInvalidAlgorithmParameterException
- if this method is overridden by a provider and the given parameters are inappropriate for this Signature
objectprotected AlgorithmParameters engineGetParameters()
Signature
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 the Signature
object, the generated parameters are returned; otherwise null
is returned.
However, if the signature scheme does not support returning the parameters as AlgorithmParameters
, null
is always returned.
Signature
object, or null
UnsupportedOperationException
- if this method is not overridden by a provider@Deprecated protected abstract Object engineGetParameter(String param) throws InvalidParameterException
param
- the string name of the parameter.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.public Object clone() throws CloneNotSupportedException
clone
in class Object
CloneNotSupportedException
- if this is called on an implementation that does not support Cloneable
.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/security/SignatureSpi.html
engineSetParameter
.