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. * * @author Benjamin Renaud * * * @see Signature */ public abstract class SignatureSpi { /** * Application-specified source of randomness. */ protected SecureRandom appRandom = null; /** * Initializes this signature object with the specified * public key for verification operations. * * @param publicKey the public key of the identity whose signature is * going to be verified. * * @exception InvalidKeyException if the key is improperly * encoded, parameters are missing, and so on. */ protected abstract void engineInitVerify(PublicKey publicKey) throws InvalidKeyException; /** * Initializes this signature object with the specified * private key for signing operations. * * @param privateKey the private key of the identity whose signature * will be generated. * * @exception InvalidKeyException if the key is improperly * encoded, parameters are missing, and so on. */ protected abstract void engineInitSign(PrivateKey privateKey) throws InvalidKeyException; /** * Initializes this 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.) * * @param privateKey the private key of the identity whose signature * will be generated. * @param random the source of randomness * * @exception InvalidKeyException if the key is improperly * encoded, parameters are missing, and so on. */ protected void engineInitSign(PrivateKey privateKey, SecureRandom random) throws InvalidKeyException { this.appRandom = random; engineInitSign(privateKey); } /** * Updates the data to be signed or verified * using the specified byte. * * @param b the byte to use for the update. * * @exception SignatureException if the engine is not initialized * properly. */ protected abstract void engineUpdate(byte b) throws SignatureException; /** * Updates the data to be signed or verified, using the * specified array of bytes, starting at the specified offset. * * @param b 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 the engine is not initialized * properly */ protected abstract void engineUpdate(byte[] b, int off, int len) throws SignatureException; /** * Updates the data to be signed or verified using the specified * ByteBuffer. Processes the {@code data.remaining()} bytes * starting at at {@code data.position()}. * Upon return, the buffer's position will be equal to its limit; * its limit will not have changed. * * @param input the ByteBuffer * @since 1.5 */ protected void engineUpdate(ByteBuffer input) { if (input.hasRemaining() == false) { return; } try { if (input.hasArray()) { byte[] b = input.array(); int ofs = input.arrayOffset(); int pos = input.position(); int lim = input.limit(); engineUpdate(b, ofs + pos, lim - pos); input.position(lim); } else { int len = input.remaining(); byte[] b = new byte[JCAUtil.getTempArraySize(len)]; while (len > 0) { int chunk = Math.min(len, b.length); input.get(b, 0, chunk); engineUpdate(b, 0, chunk); len -= chunk; } } } catch (SignatureException e) { // is specified to only occur when the engine is not initialized // this case should never occur as it is caught in Signature.java throw new ProviderException("update() failed", e); } } /** * Returns the signature bytes of all the data * updated so far. * The format of the signature depends on the underlying * signature scheme. * * @return the signature bytes of the signing operation's result. * * @exception SignatureException if the engine is not * initialized properly or if this signature algorithm is unable to * process the input data provided. */ protected abstract byte[] engineSign() throws SignatureException; /** * Finishes this signature operation and stores the resulting signature * bytes in the provided buffer {@code outbuf}, starting at * {@code 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 * {@code 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. * * @param outbuf buffer for the signature result. * * @param offset offset into {@code outbuf} where the signature is * stored. * * @param len number of bytes within {@code 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. * * @return the number of bytes placed into {@code outbuf} * * @exception SignatureException if the engine is not * initialized properly, if this signature algorithm is unable to * process the input data provided, or if {@code len} is less * than the actual signature length. * * @since 1.2 */ protected int engineSign(byte[] outbuf, int offset, int len) throws SignatureException { byte[] sig = engineSign(); if (len < sig.length) { throw new SignatureException ("partial signatures not returned"); } if (outbuf.length - offset < sig.length) { throw new SignatureException ("insufficient space in the output buffer to store the " + "signature"); } System.arraycopy(sig, 0, outbuf, offset, sig.length); return sig.length; } /** * Verifies the passed-in signature. * * @param sigBytes the signature bytes to be verified. * * @return true if the signature was verified, false if not. * * @exception 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 abstract boolean engineVerify(byte[] sigBytes) throws SignatureException; /** * Verifies the passed-in signature in the specified array * of bytes, starting at the specified offset. * *
Note: Subclasses should overwrite the default implementation. * * * @param sigBytes 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 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 */ protected boolean engineVerify(byte[] sigBytes, int offset, int length) throws SignatureException { byte[] sigBytesCopy = new byte[length]; System.arraycopy(sigBytes, offset, sigBytesCopy, 0, length); return engineVerify(sigBytesCopy); } /** * 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 {@code 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. * * @deprecated Replaced by {@link * #engineSetParameter(java.security.spec.AlgorithmParameterSpec) * engineSetParameter}. */ @Deprecated protected abstract void engineSetParameter(String param, Object value) throws InvalidParameterException; /** *
This method is overridden by providers to initialize * this signature engine with the specified parameter set. * * @param params the parameters * * @exception UnsupportedOperationException if this method is not * overridden by a provider * * @exception InvalidAlgorithmParameterException if this method is * overridden by a provider and the given parameters * are inappropriate for this signature engine */ protected void engineSetParameter(AlgorithmParameterSpec params) throws InvalidAlgorithmParameterException { throw new UnsupportedOperationException(); } /** *
This method is overridden by providers to return the * parameters used with this signature engine, or null * if this signature engine does not use any parameters. * *
The returned parameters may be the same that were used to initialize * this signature engine, or may contain a combination of default and * randomly generated parameter values used by the underlying signature * implementation if this signature engine requires algorithm parameters * but was not initialized with any. * * @return the parameters used with this signature engine, or null if this * signature engine does not use any parameters * * @exception UnsupportedOperationException if this method is * not overridden by a provider * @since 1.4 */ protected AlgorithmParameters engineGetParameters() { throw new UnsupportedOperationException(); } /** * 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 {@code param} is an * invalid parameter for this engine, or another exception occurs while * trying to get this parameter. * * @deprecated Deprecated. */ @Deprecated // Android-changed add "Deprecated." protected abstract Object engineGetParameter(String param) throws InvalidParameterException; /** * 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 {@code Cloneable}. */ public Object clone() throws CloneNotSupportedException { if (this instanceof Cloneable) { return super.clone(); } else { throw new CloneNotSupportedException(); } } }