java.security

Class Signature

java.lang.Object

java.security.SignatureSpi

java.security.Signature

public abstract class Signature
extends SignatureSpi

Signature is an engine class which is capable of creating and verifying digital signatures, using different algorithms that have been registered with the Security class.

See Also:

SignatureSpi

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	SIGN Constant that indicates that this Signature instance has been initialized for signing.
protected int	state Represents the current state of this Signature.
protected static int	UNINITIALIZED Constant that indicates that this Signature instance has not yet been initialized.
protected static int	VERIFY Constant that indicates that this Signature instance has been initialized for verification.

Fields inherited from class java.security.SignatureSpi

appRandom

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Signature(String algorithm) Constructs a new instance of Signature with the name of the algorithm to use.

Method Summary

Modifier and Type	Method and Description
String	getAlgorithm() Returns the name of the algorithm of this Signature.
SignatureSpi	getCurrentSpi() Returns the SignatureSpi backing this Signature or null if no SignatureSpi is backing this Signature.
static Signature	getInstance(String algorithm) Returns a new instance of Signature that utilizes the specified algorithm.
static Signature	getInstance(String algorithm, Provider provider) Returns a new instance of Signature that utilizes the specified algorithm from the specified provider.
static Signature	getInstance(String algorithm, String provider) Returns a new instance of Signature that utilizes the specified algorithm from the specified provider.
Object	getParameter(String param) Deprecated. There is no generally accepted parameter naming convention.
AlgorithmParameters	getParameters() Returns the AlgorithmParameters of this Signature instance.
Provider	getProvider() Returns the provider associated with this Signature.
void	initSign(PrivateKey privateKey) Initializes this Signature instance for signing, using the private key of the identity whose signature is going to be generated.
void	initSign(PrivateKey privateKey, SecureRandom random) Initializes this Signature instance for signing, using the private key of the identity whose signature is going to be generated and the specified source of randomness.
void	initVerify(Certificate certificate) Initializes this Signature instance for signature verification, using the certificate of the identity whose signature is going to be verified.
void	initVerify(PublicKey publicKey) Initializes this Signature instance for signature verification, using the public key of the identity whose signature is going to be verified.
void	setParameter(AlgorithmParameterSpec params) Sets the specified AlgorithmParameterSpec.
void	setParameter(String param, Object value) Deprecated. Use setParameter(AlgorithmParameterSpec) instead.
byte[]	sign() Generates and returns the signature of all updated data.
int	sign(byte[] outbuf, int offset, int len) Generates and stores the signature of all updated data in the provided byte[] at the specified position with the specified length.
String	toString() Returns a string containing a concise, human-readable description of this Signature including its algorithm and its state.
void	update(byte b) Updates the data to be verified or to be signed, using the specified byte.
void	update(byte[] data) Updates the data to be verified or to be signed, using the specified byte[].
void	update(byte[] data, int off, int len) Updates the data to be verified or to be signed, using the given byte[], starting form the specified index for the specified length.
void	update(ByteBuffer data) Updates the data to be verified or to be signed, using the specified ByteBuffer.
boolean	verify(byte[] signature) Indicates whether the given signature can be verified using the public key or a certificate of the signer.
boolean	verify(byte[] signature, int offset, int length) Indicates whether the given signature starting at index offset with length bytes can be verified using the public key or a certificate of the signer.

Methods inherited from class java.security.SignatureSpi

clone, engineGetParameter, engineGetParameters, engineInitSign, engineInitSign, engineInitVerify, engineSetParameter, engineSetParameter, engineSign, engineSign, engineUpdate, engineUpdate, engineUpdate, engineVerify, engineVerify

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

UNINITIALIZED

protected static final int UNINITIALIZED

Constant that indicates that this Signature instance has not yet been initialized.

See Also:

Constant Field Values

SIGN

protected static final int SIGN

Constant that indicates that this Signature instance has been initialized for signing.

See Also:

Constant Field Values

VERIFY

protected static final int VERIFY

Constant that indicates that this Signature instance has been initialized for verification.

See Also:

Constant Field Values

state

protected int state

Represents the current state of this Signature. The three possible states are UNINITIALIZED, SIGN or VERIFY.

Constructor Detail

Signature

protected Signature(String algorithm)

Constructs a new instance of Signature with the name of the algorithm to use.

Parameters:

algorithm - the name of algorithm to use.

Method Detail

getInstance

public static Signature getInstance(String algorithm)
                             throws NoSuchAlgorithmException

Returns a new instance of Signature that utilizes the specified algorithm.

Parameters:

algorithm - the name of the algorithm to use.

Returns:

a new instance of Signature that utilizes the specified algorithm.

Throws:

NoSuchAlgorithmException - if the specified algorithm is not available.

NullPointerException - if algorithm is null.

getInstance

public static Signature getInstance(String algorithm,
                                    String provider)
                             throws NoSuchAlgorithmException,
                                    NoSuchProviderException

Returns a new instance of Signature that utilizes the specified algorithm from the specified provider.

Parameters:

algorithm - the name of the algorithm to use.

provider - the name of the provider.

Returns:

a new instance of Signature that utilizes the specified algorithm from the specified provider.

Throws:

NoSuchAlgorithmException - if the specified algorithm is not available.

NoSuchProviderException - if the specified provider is not available.

NullPointerException - if algorithm is null.

IllegalArgumentException - if provider == null || provider.isEmpty()

getInstance

public static Signature getInstance(String algorithm,
                                    Provider provider)
                             throws NoSuchAlgorithmException

Returns a new instance of Signature that utilizes the specified algorithm from the specified provider. The provider supplied does not have to be registered.

Parameters:

algorithm - the name of the algorithm to use.

provider - the security provider.

Returns:

a new instance of Signature that utilizes the specified algorithm from the specified provider.

Throws:

NoSuchAlgorithmException - if the specified algorithm is not available.

NullPointerException - if algorithm is null.

IllegalArgumentException - if provider == null

getProvider

public final Provider getProvider()

Returns the provider associated with this Signature.

Returns:

the provider associated with this Signature.

getCurrentSpi

public SignatureSpi getCurrentSpi()

Returns the SignatureSpi backing this Signature or null if no SignatureSpi is backing this Signature.

getAlgorithm

public final String getAlgorithm()

Returns the name of the algorithm of this Signature.

Returns:

the name of the algorithm of this Signature.

initVerify

public final void initVerify(PublicKey publicKey)
                      throws InvalidKeyException

Initializes this Signature instance for signature verification, using the public key of the identity whose signature is going to be verified.

Parameters:

publicKey - the public key.

Throws:

InvalidKeyException - if publicKey is not valid.

initVerify

public final void initVerify(Certificate certificate)
                      throws InvalidKeyException

Initializes this Signature instance for signature verification, using the certificate of the identity whose signature is going to be verified.

If the given certificate is an instance of X509Certificate and has a key usage parameter that indicates, that this certificate is not to be used for signing, an InvalidKeyException is thrown.

Parameters:

certificate - the certificate used to verify a signature.

Throws:

InvalidKeyException - if the publicKey in the certificate is not valid or not to be used for signing.

initSign

public final void initSign(PrivateKey privateKey)
                    throws InvalidKeyException

Initializes this Signature instance for signing, using the private key of the identity whose signature is going to be generated.

Parameters:

privateKey - the private key.

Throws:

InvalidKeyException - if privateKey is not valid.

initSign

public final void initSign(PrivateKey privateKey,
                           SecureRandom random)
                    throws InvalidKeyException

Initializes this Signature instance for signing, using the private key of the identity whose signature is going to be generated and the specified source of randomness.

Parameters:

privateKey - the private key.

random - the SecureRandom to use.

Throws:

InvalidKeyException - if privateKey is not valid.

sign

public final byte[] sign()
                  throws SignatureException

Generates and returns the signature of all updated data.

This Signature instance is reset to the state of its last initialization for signing and thus can be used for another signature from the same identity.

Returns:

the signature of all updated data.

Throws:

SignatureException - if this Signature instance is not initialized properly.

sign

public final int sign(byte[] outbuf,
                      int offset,
                      int len)
               throws SignatureException

Generates and stores the signature of all updated data in the provided byte[] at the specified position with the specified length.

This Signature instance is reset to the state of its last initialization for signing and thus can be used for another signature from the same identity.

Parameters:

outbuf - the buffer to store the signature.

offset - the index of the first byte in outbuf to store.

len - the number of bytes allocated for the signature.

Returns:

the number of bytes stored in outbuf.

Throws:

SignatureException - if this Signature instance is not initialized properly.

IllegalArgumentException - if offset or len are not valid in respect to outbuf.

verify

public final boolean verify(byte[] signature)
                     throws SignatureException

Indicates whether the given signature can be verified using the public key or a certificate of the signer.

This Signature instance is reset to the state of its last initialization for verifying and thus can be used to verify another signature of the same signer.

Parameters:

signature - the signature to verify.

Returns:

true if the signature was verified, false otherwise.

Throws:

SignatureException - if this Signature instance is not initialized properly.

verify

public final boolean verify(byte[] signature,
                            int offset,
                            int length)
                     throws SignatureException

Indicates whether the given signature starting at index offset with length bytes can be verified using the public key or a certificate of the signer.

This Signature instance is reset to the state of its last initialization for verifying and thus can be used to verify another signature of the same signer.

Parameters:

signature - the byte[] containing the signature to verify.

offset - the start index in signature of the signature.

length - the number of bytes allocated for the signature.

Returns:

true if the signature was verified, false otherwise.

Throws:

SignatureException - if this Signature instance is not initialized properly.

IllegalArgumentException - if offset or length are not valid in respect to signature.

update

public final void update(byte b)
                  throws SignatureException

Updates the data to be verified or to be signed, using the specified byte.

Parameters:

b - the byte to update with.

Throws:

SignatureException - if this Signature instance is not initialized properly.

update

public final void update(byte[] data)
                  throws SignatureException

Updates the data to be verified or to be signed, using the specified byte[].

Parameters:

data - the byte array to update with.

Throws:

SignatureException - if this Signature instance is not initialized properly.

update

public final void update(byte[] data,
                         int off,
                         int len)
                  throws SignatureException

Updates the data to be verified or to be signed, using the given byte[], starting form the specified index for the specified length.

Parameters:

data - the byte array to update with.

off - the start index in data of the data.

len - the number of bytes to use.

Throws:

SignatureException - if this Signature instance is not initialized properly.

update

public final void update(ByteBuffer data)
                  throws SignatureException

Updates the data to be verified or to be signed, using the specified ByteBuffer.

Parameters:

data - the ByteBuffer to update with.

Throws:

SignatureException - if this Signature instance is not initialized properly.

toString

public String toString()

Returns a string containing a concise, human-readable description of this Signature including its algorithm and its state.

Overrides:

toString in class Object

Returns:

a printable representation for this Signature.

setParameter

@Deprecated
public final void setParameter(String param,
                                           Object value)
                                    throws InvalidParameterException

Deprecated. Use setParameter(AlgorithmParameterSpec) instead.

Sets the specified parameter to the given value.

Parameters:

param - the name of the parameter.

value - the parameter value.

Throws:

InvalidParameterException - if the parameter is invalid, already set or is not allowed to be changed.

setParameter

public final void setParameter(AlgorithmParameterSpec params)
                        throws InvalidAlgorithmParameterException

Sets the specified AlgorithmParameterSpec.

Parameters:

params - the parameter to set.

Throws:

InvalidAlgorithmParameterException - if the parameter is invalid, already set or is not allowed to be changed.

getParameters

public final AlgorithmParameters getParameters()

Returns the AlgorithmParameters of this Signature instance.

Returns:

the AlgorithmParameters of this Signature instance, maybe null.

getParameter

@Deprecated
public final Object getParameter(String param)
                                      throws InvalidParameterException

Deprecated. There is no generally accepted parameter naming convention.

Returns the value of the parameter with the specified name.

Parameters:

param - the name of the requested parameter value

Returns:

the value of the parameter with the specified name, maybe null.

Throws:

InvalidParameterException - if param is not a valid parameter for this Signature or an other error occurs.