File	Doc	Category	Size	Date	Package
Signature.java	API Doc	Java SE 5 API	42437	Fri Aug 26 14:57:16 BST 2005	java.security

Signature

• java.lang.Object
  • java.security.SignatureSpi

Fields Summary
private static final Debug	debug
private String	algorithm
Provider	provider
protected static final int	UNINITIALIZED Possible {@link #state} value, signifying that this signature object has not yet been initialized.
protected static final int	SIGN Possible {@link #state} value, signifying that this signature object has been initialized for signing.
protected static final int	VERIFY Possible {@link #state} value, signifying that this signature object has been initialized for verification.
protected int	state Current state of this signature object.
private static final String	RSA_SIGNATURE
private static final String	RSA_CIPHER
private static final List	rsaIds
private static final Map	signatureInfo

Constructors Summary
protected Signature(String algorithm) Creates a Signature object for the specified algorithm. param 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. this.algorithm = algorithm;

Methods Summary
void	chooseFirstProvider() // empty, overridden in Delegate
public java.lang.Object	clone() Returns a clone if the implementation is cloneable. return a clone if the implementation is cloneable. exception CloneNotSupportedException if this is called on an implementation that does not support Cloneable. if (this instanceof Cloneable) { return super.clone(); } else { throw new CloneNotSupportedException(); }
public final java.lang.String	getAlgorithm() Returns the name of the algorithm for this signature object. return the name of the algorithm for this signature object. return this.algorithm;
public static java.security.Signature	getInstance(java.lang.String algorithm) Generates a Signature object that implements the specified digest algorithm. If the default provider package provides an implementation of the requested digest algorithm, an instance of Signature containing that implementation is returned. If the algorithm is not available in the default package, other packages are searched. param 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. return the new Signature object. exception NoSuchAlgorithmException if the algorithm is not available in the environment. List list; if (algorithm.equalsIgnoreCase(RSA_SIGNATURE)) { list = GetInstance.getServices(rsaIds); } else { list = GetInstance.getServices("Signature", algorithm); } Iterator t = list.iterator(); if (t.hasNext() == false) { throw new NoSuchAlgorithmException (algorithm + " Signature not available"); } // try services until we find an Spi or a working Signature subclass NoSuchAlgorithmException failure; do { Service s = (Service)t.next(); if (isSpi(s)) { return new Delegate(s, t, algorithm); } else { // must be a subclass of Signature, disable dynamic selection try { Instance instance = GetInstance.getInstance(s, SignatureSpi.class); return getInstance(instance, algorithm); } catch (NoSuchAlgorithmException e) { failure = e; } } } while (t.hasNext()); throw failure;
private static java.security.Signature	getInstance(sun.security.jca.GetInstance.Instance instance, java.lang.String algorithm) Signature sig; if (instance.impl instanceof Signature) { sig = (Signature)instance.impl; } else { SignatureSpi spi = (SignatureSpi)instance.impl; sig = new Delegate(spi, algorithm); } sig.provider = instance.provider; return sig;
public static java.security.Signature	getInstance(java.lang.String algorithm, java.lang.String provider) Generates a Signature object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider. param algorithm the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names. param provider the name of the provider. return the new Signature object. exception NoSuchAlgorithmException if the algorithm is not available in the package supplied by the requested provider. exception NoSuchProviderException if the provider is not available in the environment. exception IllegalArgumentException if the provider name is null or empty. see Provider if (algorithm.equalsIgnoreCase(RSA_SIGNATURE)) { // exception compatibility with existing code if ((provider == null) || (provider.length() == 0)) { throw new IllegalArgumentException("missing provider"); } Provider p = Security.getProvider(provider); if (p == null) { throw new NoSuchProviderException ("no such provider: " + provider); } return getInstanceRSA(p); } Instance instance = GetInstance.getInstance ("Signature", SignatureSpi.class, algorithm, provider); return getInstance(instance, algorithm);
public static java.security.Signature	getInstance(java.lang.String algorithm, java.security.Provider provider) Generates a Signature object implementing the specified algorithm, as supplied from the specified provider, if such an algorithm is available from the provider. Note: the provider doesn't have to be registered. param algorithm the name of the algorithm requested. See Appendix A in the Java Cryptography Architecture API Specification & Reference for information about standard algorithm names. param provider the provider. return the new Signature object. exception NoSuchAlgorithmException if the algorithm is not available in the package supplied by the requested provider. exception IllegalArgumentException if the provider is null. see Provider since 1.4 if (algorithm.equalsIgnoreCase(RSA_SIGNATURE)) { // exception compatibility with existing code if (provider == null) { throw new IllegalArgumentException("missing provider"); } return getInstanceRSA(provider); } Instance instance = GetInstance.getInstance ("Signature", SignatureSpi.class, algorithm, provider); return getInstance(instance, algorithm);
private static java.security.Signature	getInstanceRSA(java.security.Provider p) // try Signature first Service s = p.getService("Signature", RSA_SIGNATURE); if (s != null) { Instance instance = GetInstance.getInstance(s, SignatureSpi.class); return getInstance(instance, RSA_SIGNATURE); } // check Cipher try { Cipher c = Cipher.getInstance(RSA_CIPHER, p); return new Delegate(new CipherAdapter(c), RSA_SIGNATURE); } catch (GeneralSecurityException e) { // throw Signature style exception message to avoid confusion, // but append Cipher exception as cause throw new NoSuchAlgorithmException("no such algorithm: " + RSA_SIGNATURE + " for provider " + p.getName(), e); }
public final java.lang.Object	getParameter(java.lang.String param) 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 param the string name of the parameter. return the object that represents the parameter value, or null if there is none. exception InvalidParameterException if param is an invalid parameter for this engine, or another exception occurs while trying to get this parameter. see #setParameter(String, Object) deprecated return engineGetParameter(param);
public final java.security.AlgorithmParameters	getParameters() 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. return the parameters used with this signature, or null if this signature does not use any parameters. see #setParameter(AlgorithmParameterSpec) return engineGetParameters();
public final java.security.Provider	getProvider() Returns the provider of this signature object. return the provider of this signature object chooseFirstProvider(); return this.provider;
public final void	initSign(java.security.PrivateKey privateKey) Initialize this object for signing. If this method is called again with a different argument, it negates the effect of this call. param privateKey the private key of the identity whose signature is going to be generated. exception InvalidKeyException if the key is invalid. engineInitSign(privateKey); state = SIGN;
public final void	initSign(java.security.PrivateKey privateKey, java.security.SecureRandom random) Initialize this object for signing. If this method is called again with a different argument, it negates the effect of this call. param privateKey the private key of the identity whose signature is going to be generated. param random the source of randomness for this signature. exception InvalidKeyException if the key is invalid. engineInitSign(privateKey, random); state = SIGN;
public final void	initVerify(java.security.PublicKey publicKey) Initializes this object for verification. If this method is called again with a different argument, it negates the effect of this call. param publicKey the public key of the identity whose signature is going to be verified. exception InvalidKeyException if the key is invalid. engineInitVerify(publicKey); state = VERIFY;
public final void	initVerify(java.security.cert.Certificate certificate) 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. param certificate the certificate of the identity whose signature is going to be verified. exception 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. // If the certificate is of type X509Certificate, // we should check whether it has a Key Usage // extension marked as critical. if (certificate instanceof java.security.cert.X509Certificate) { // Check whether the cert has a key usage extension // marked as a critical extension. // The OID for KeyUsage extension is 2.5.29.15. X509Certificate cert = (X509Certificate)certificate; Set critSet = cert.getCriticalExtensionOIDs(); if (critSet != null && !critSet.isEmpty() && critSet.contains("2.5.29.15")) { boolean[] keyUsageInfo = cert.getKeyUsage(); // keyUsageInfo[0] is for digitalSignature. if ((keyUsageInfo != null) && (keyUsageInfo[0] == false)) throw new InvalidKeyException("Wrong key usage"); } } PublicKey publicKey = certificate.getPublicKey(); engineInitVerify(publicKey); state = VERIFY;
private static boolean	isSpi(java.security.Provider.Service s) signatureInfo = new ConcurrentHashMap<String,Boolean>(); Boolean TRUE = Boolean.TRUE; // pre-initialize with values for our SignatureSpi implementations signatureInfo.put("sun.security.provider.DSA$RawDSA", TRUE); signatureInfo.put("sun.security.provider.DSA$SHA1withDSA", TRUE); signatureInfo.put("sun.security.rsa.RSASignature$MD2withRSA", TRUE); signatureInfo.put("sun.security.rsa.RSASignature$MD5withRSA", TRUE); signatureInfo.put("sun.security.rsa.RSASignature$SHA1withRSA", TRUE); signatureInfo.put("sun.security.rsa.RSASignature$SHA256withRSA", TRUE); signatureInfo.put("sun.security.rsa.RSASignature$SHA384withRSA", TRUE); signatureInfo.put("sun.security.rsa.RSASignature$SHA512withRSA", TRUE); signatureInfo.put("com.sun.net.ssl.internal.ssl.RSASignature", TRUE); signatureInfo.put("sun.security.pkcs11.P11Signature", TRUE); if (s.getType().equals("Cipher")) { // must be a CipherSpi, which we can wrap with the CipherAdapter return true; } String className = s.getClassName(); Boolean result = signatureInfo.get(className); if (result == null) { try { Object instance = s.newInstance(null); // Signature extends SignatureSpi // so it is a "real" Spi if it is an // instance of SignatureSpi but not Signature boolean r = (instance instanceof SignatureSpi) && (instance instanceof Signature == false); if ((debug != null) && (r == false)) { debug.println("Not a SignatureSpi " + className); debug.println("Delayed provider selection may not be " + "available for algorithm " + s.getAlgorithm()); } result = Boolean.valueOf(r); signatureInfo.put(className, result); } catch (Exception e) { // something is wrong, assume not an SPI return false; } } return result.booleanValue();
public final void	setParameter(java.lang.String param, java.lang.Object value) 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 param the string identifier of the parameter. param value the parameter value. exception 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. see #getParameter deprecated Use {@link #setParameter(java.security.spec.AlgorithmParameterSpec) setParameter}. engineSetParameter(param, value);
public final void	setParameter(java.security.spec.AlgorithmParameterSpec params) Initializes this signature engine with the specified parameter set. param params the parameters exception InvalidAlgorithmParameterException if the given parameters are inappropriate for this signature engine see #getParameters engineSetParameter(params);
public final byte[]	sign() 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. return the signature bytes of the signing operation's result. exception SignatureException if this signature object is not initialized properly or if this signature algorithm is unable to process the input data provided. if (state == SIGN) { return engineSign(); } throw new SignatureException("object not initialized for " + "signing");
public final int	sign(byte[] outbuf, int offset, int len) 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. param outbuf buffer for the signature result. param offset offset into outbuf where the signature is stored. param len number of bytes within outbuf allotted for the signature. return the number of bytes placed into outbuf. exception 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. since 1.2 if (outbuf == null) { throw new IllegalArgumentException("No output buffer given"); } if (outbuf.length - offset < len) { throw new IllegalArgumentException ("Output buffer too small for specified offset and length"); } if (state != SIGN) { throw new SignatureException("object not initialized for " + "signing"); } return engineSign(outbuf, offset, len);
public java.lang.String	toString() Returns a string representation of this signature object, providing information that includes the state of the object and the name of the algorithm used. return a string representation of this signature object. String initState = ""; switch (state) { case UNINITIALIZED: initState = "<not initialized>"; break; case VERIFY: initState = "<initialized for verifying>"; break; case SIGN: initState = "<initialized for signing>"; break; } return "Signature object: " + getAlgorithm() + initState;
public final void	update(byte b) Updates the data to be signed or verified by a byte. param b the byte to use for the update. exception SignatureException if this signature object is not initialized properly. if (state == VERIFY || state == SIGN) { engineUpdate(b); } else { throw new SignatureException("object not initialized for " + "signature or verification"); }
public final void	update(byte[] data) Updates the data to be signed or verified, using the specified array of bytes. param data the byte array to use for the update. exception SignatureException if this signature object is not initialized properly. update(data, 0, data.length);
public final void	update(byte[] data, int off, int len) Updates the data to be signed or verified, using the specified array of bytes, starting at the specified offset. param data the array of bytes. param off the offset to start from in the array of bytes. param len the number of bytes to use, starting at offset. exception SignatureException if this signature object is not initialized properly. if (state == SIGN || state == VERIFY) { engineUpdate(data, off, len); } else { throw new SignatureException("object not initialized for " + "signature or verification"); }
public final void	update(java.nio.ByteBuffer data) 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. param data the ByteBuffer exception SignatureException if this signature object is not initialized properly. since 1.5 if ((state != SIGN) && (state != VERIFY)) { throw new SignatureException("object not initialized for " + "signature or verification"); } if (data == null) { throw new NullPointerException(); } engineUpdate(data);
public final boolean	verify(byte[] signature) 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. param signature the signature bytes to be verified. return true if the signature was verified, false if not. exception 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. if (state == VERIFY) { return engineVerify(signature); } throw new SignatureException("object not initialized for " + "verification");
public final boolean	verify(byte[] signature, int offset, int length) 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. param signature the signature bytes to be verified. param offset the offset to start from in the array of bytes. param length the number of bytes to use, starting at offset. return true if the signature was verified, false if not. exception 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. exception 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. if (state == VERIFY) { if ((signature == null) || (offset < 0) || (length < 0) || (offset + length > signature.length)) { throw new IllegalArgumentException("Bad arguments"); } return engineVerify(signature, offset, length); } throw new SignatureException("object not initialized for " + "verification");