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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.security;

import java.security.spec.AlgorithmParameterSpec;
import java.util.*;
import java.io.*;

import java.nio.ByteBuffer;

import sun.security.jca.JCAUtil;

/**
 * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
 * for the {@code 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.
 *
 * <p> 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
 * @since 1.2
 *
 *
 * @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.
 *
 * <p>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 {@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.
 *
 * <p>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.
 *
 * <p> 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;

 /**
 * <p>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();
 }

 /**
 * <p>This method is overridden by providers to return the parameters
 * used with this signature engine.
 *
 * <p> If this signature engine has been previously initialized with
 * parameters (by calling the {@code engineSetParameter} method), this
 * method returns the same parameters. If this signature engine has not been
 * initialized with parameters, this method may return a combination of
 * default and randomly generated parameter values if the underlying
 * signature implementation supports it and can successfully generate
 * them. Otherwise, {@code null} is returned.
 *
 * @return the parameters used with this signature engine, or {@code null}
 *
 * @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 {@code 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
 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();
 }
 }
}