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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.harmony.security.provider.crypto;
import java.security.DigestException;
import java.security.MessageDigestSpi;
import java.util.Arrays;
import static org.apache.harmony.security.provider.crypto.SHA1Constants.*;
/**
* This class extends the MessageDigestSpi class implementing all its abstract methods;
* it overrides the "Object clone()" and "int engineGetDigestLength()" methods.
* The class implements the Cloneable interface.
*/
public class SHA1_MessageDigestImpl extends MessageDigestSpi implements Cloneable {
private int[] buffer; // buffer has the following structure:
// - 0-16 - frame for accumulating a message
// - 17-79 - for SHA1Impl methods
// - 80 - unused
// - 81 - to store length of the message
// - 82-86 - frame for current message digest
private byte[] oneByte; // one byte buffer needed to use in engineUpdate(byte)
// having buffer as private field is just optimization
private long messageLength; // total length of bytes supplied by user
/**
* The constructor creates needed buffers and sets the engine at initial state
*/
public SHA1_MessageDigestImpl() {
// BYTES_OFFSET +6 is minimal length required by methods in SHA1Impl
buffer = new int[BYTES_OFFSET +6];
oneByte = new byte[1];
engineReset();
}
/**
* The method performs final actions and invokes the "computeHash(int[])" method.
* In case if there is no enough words in current frame
* after processing its data, extra frame is prepared and
* the "computeHash(int[])" method is invoked second time.
*
* After processing, the method resets engine's state
*
* @param
* digest - byte array
* @param
* offset - offset in digest
*/
private void processDigest(byte[] digest, int offset) {
int i, j; // implementation variables
int lastWord; //
long nBits = messageLength <<3 ; // length has to be calculated before padding
engineUpdate( (byte) 0x80 ); // beginning byte in padding
i = 0; // i contains number of beginning word for following loop
lastWord = (buffer[BYTES_OFFSET] + 3)>>2 ; // computing of # of full words by shifting
// # of bytes
// possible cases:
//
// - buffer[BYTES_OFFSET] == 0 - buffer frame is empty,
// padding byte was 64th in previous frame
// current frame should contain only message's length
//
// - lastWord < 14 - two last, these are 14 & 15, words in 16 word frame are free;
// no extra frame needed
// - lastWord = 14 - only one last, namely 15-th, word in frame doesn't contain bytes;
// extra frame is needed
// - lastWord > 14 - last word in frame is not full;
// extra frame is needed
if ( buffer[BYTES_OFFSET] != 0 ) {
if ( lastWord < 15 ) {
i = lastWord;
} else {
if ( lastWord == 15 ) {
buffer[15] = 0; // last word in frame is set to "0"
}
SHA1Impl.computeHash(buffer);
i = 0;
}
}
Arrays.fill(buffer, i, 14, 0);
buffer[14] = (int)( nBits >>>32 );
buffer[15] = (int)( nBits & 0xFFFFFFFF );
SHA1Impl.computeHash(buffer);
// converting 5-word frame into 20 bytes
j = offset;
for ( i = HASH_OFFSET; i < HASH_OFFSET +5; i++ ) {
int k = buffer[i];
digest[j ] = (byte) ( k >>>24 ); // getting first byte from left
digest[j+1] = (byte) ( k >>>16 ); // getting second byte from left
digest[j+2] = (byte) ( k >>> 8 ); // getting third byte from left
digest[j+3] = (byte) ( k ); // getting fourth byte from left
j += 4;
}
engineReset();
}
// methods specified in java.security.MessageDigestSpi
/**
* Returns a "deep" copy of this SHA1MDImpl object.
*
* The method overrides "clone()" in class Object.
*
* @return
* a clone of this object
*/
public Object clone() throws CloneNotSupportedException {
SHA1_MessageDigestImpl cloneObj = (SHA1_MessageDigestImpl) super.clone();
cloneObj.buffer = buffer.clone();
cloneObj.oneByte = oneByte.clone();
return cloneObj;
}
/**
* Computes a message digest value.
*
* The method resets the engine.
*
* The method overrides "engineDigest()" in class MessageDigestSpi.
*
* @return
* byte array containing message digest value
*/
protected byte[] engineDigest() {
byte[] hash = new byte[DIGEST_LENGTH];
processDigest(hash, 0);
return hash;
}
/**
* Computes message digest value.
* Upon return, the value is stored in "buf" buffer beginning "offset" byte.
*
* The method resets the engine.
*
* The method overrides "engineDigest(byte[],int,int) in class MessageDigestSpi.
*
* @param
* buf byte array to store a message digest returned
* @param
* offset a position in the array for first byte of the message digest
* @param
* len number of bytes within buffer allotted for the message digest;
* as this implementation doesn't provide partial digests,
* len should be >= 20, DigestException is thrown otherwise
* @return
* the length of the message digest stored in the "buf" buffer;
* in this implementation the length=20
*
* @throws IllegalArgumentException
* if null is passed to the "buf" argument
* if offset + len > buf.length
* if offset > buf.length or len > buf.length
*
* @throws DigestException
* if len < 20
*
* @throws ArrayIndexOutOfBoundsException
* if offset < 0
*/
protected int engineDigest(byte[] buf, int offset, int len) throws DigestException {
if (buf == null) {
throw new IllegalArgumentException("buf == null");
}
if (offset > buf.length || len > buf.length || (len + offset) > buf.length) {
throw new IllegalArgumentException();
}
if (len < DIGEST_LENGTH) {
throw new DigestException("len < DIGEST_LENGTH");
}
if (offset < 0) {
throw new ArrayIndexOutOfBoundsException(offset);
}
processDigest(buf, offset);
return DIGEST_LENGTH;
}
/**
* Returns a message digest length.
*
* The method overrides "engineGetDigestLength()" in class MessageDigestSpi.
*
* @return
* total length of current message digest as an int value
*/
protected int engineGetDigestLength() {
return DIGEST_LENGTH;
}
/**
* Resets the engine.
*
* The method overrides "engineReset()" in class MessageDigestSpi.
*/
protected void engineReset() {
messageLength = 0;
buffer[BYTES_OFFSET] = 0;
buffer[HASH_OFFSET ] = H0;
buffer[HASH_OFFSET +1] = H1;
buffer[HASH_OFFSET +2] = H2;
buffer[HASH_OFFSET +3] = H3;
buffer[HASH_OFFSET +4] = H4;
}
/**
* Supplements a byte to current message.
*
* The method overrides "engineUpdate(byte)" in class MessageDigestSpi.
*
* @param
* input byte to add to current message
*/
protected void engineUpdate(byte input) {
oneByte[0] = input;
SHA1Impl.updateHash( buffer, oneByte, 0, 0 );
messageLength++;
}
/**
* Updates current message.
*
* The method overrides "engineUpdate(byte[],int,int)" in class MessageDigestSpi.
*
* The method silently returns if "len" <= 0.
*
* @param
* input a byte array
* @param
* offset a number of first byte in the "input" array to use for updating
* @param
* len a number of bytes to use
*
* @throws NullPointerException
* if null is passed to the "buf" argument
*
* @throws IllegalArgumentException
* if offset > buf.length or len > buf.length or
* (len + offset) > buf.length
* @throws ArrayIndexOutOfBoundsException
* offset < 0
*/
protected void engineUpdate(byte[] input, int offset, int len) {
if (input == null) {
throw new IllegalArgumentException("input == null");
}
if (len <= 0) {
return;
}
if (offset < 0) {
throw new ArrayIndexOutOfBoundsException(offset);
}
if (offset > input.length || len > input.length || (len + offset) > input.length) {
throw new IllegalArgumentException();
}
SHA1Impl.updateHash(buffer, input, offset, offset + len -1 );
messageLength += len;
}
}
