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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package sun.security.provider;
import java.security.MessageDigestSpi;
import java.security.DigestException;
import java.security.ProviderException;
/**
* Common base message digest implementation for the Sun provider.
* It implements all the JCA methods as suitable for a Java message digest
* implementation of an algorithm based on a compression function (as all
* commonly used algorithms are). The individual digest subclasses only need to
* implement the following methods:
*
* . abstract void implCompress(byte[] b, int ofs);
* . abstract void implDigest(byte[] out, int ofs);
* . abstract void implReset();
* . public abstract Object clone();
*
* See the inline documentation for details.
*
* @since 1.5
* @author Andreas Sterbenz
*/
abstract class DigestBase extends MessageDigestSpi implements Cloneable {
// one element byte array, temporary storage for update(byte)
private byte[] oneByte;
// algorithm name to use in the exception message
private final String algorithm;
// length of the message digest in bytes
private final int digestLength;
// size of the input to the compression function in bytes
private final int blockSize;
// buffer to store partial blocks, blockSize bytes large
// Subclasses should not access this array directly except possibly in their
// implDigest() method. See MD5.java as an example.
final byte[] buffer;
// offset into buffer
private int bufOfs;
// number of bytes processed so far. subclasses should not modify
// this value.
// also used as a flag to indicate reset status
// -1: need to call engineReset() before next call to update()
// 0: is already reset
long bytesProcessed;
/**
* Main constructor.
*/
DigestBase(String algorithm, int digestLength, int blockSize) {
super();
this.algorithm = algorithm;
this.digestLength = digestLength;
this.blockSize = blockSize;
buffer = new byte[blockSize];
}
/**
* Constructor for cloning. Replicates common data.
*/
DigestBase(DigestBase base) {
this.algorithm = base.algorithm;
this.digestLength = base.digestLength;
this.blockSize = base.blockSize;
this.buffer = base.buffer.clone();
this.bufOfs = base.bufOfs;
this.bytesProcessed = base.bytesProcessed;
}
// return digest length. See JCA doc.
protected final int engineGetDigestLength() {
return digestLength;
}
// single byte update. See JCA doc.
protected final void engineUpdate(byte b) {
if (oneByte == null) {
oneByte = new byte[1];
}
oneByte[0] = b;
engineUpdate(oneByte, 0, 1);
}
// array update. See JCA doc.
protected final void engineUpdate(byte[] b, int ofs, int len) {
if (len == 0) {
return;
}
if ((ofs < 0) || (len < 0) || (ofs > b.length - len)) {
throw new ArrayIndexOutOfBoundsException();
}
if (bytesProcessed < 0) {
engineReset();
}
bytesProcessed += len;
// if buffer is not empty, we need to fill it before proceeding
if (bufOfs != 0) {
int n = Math.min(len, blockSize - bufOfs);
System.arraycopy(b, ofs, buffer, bufOfs, n);
bufOfs += n;
ofs += n;
len -= n;
if (bufOfs >= blockSize) {
// compress completed block now
implCompress(buffer, 0);
bufOfs = 0;
}
}
// compress complete blocks
while (len >= blockSize) {
implCompress(b, ofs);
len -= blockSize;
ofs += blockSize;
}
// copy remainder to buffer
if (len > 0) {
System.arraycopy(b, ofs, buffer, 0, len);
bufOfs = len;
}
}
// reset this object. See JCA doc.
protected final void engineReset() {
if (bytesProcessed == 0) {
// already reset, ignore
return;
}
implReset();
bufOfs = 0;
bytesProcessed = 0;
}
// return the digest. See JCA doc.
protected final byte[] engineDigest() {
byte[] b = new byte[digestLength];
try {
engineDigest(b, 0, b.length);
} catch (DigestException e) {
throw (ProviderException)
new ProviderException("Internal error").initCause(e);
}
return b;
}
// return the digest in the specified array. See JCA doc.
protected final int engineDigest(byte[] out, int ofs, int len)
throws DigestException {
if (len < digestLength) {
throw new DigestException("Length must be at least "
+ digestLength + " for " + algorithm + "digests");
}
if ((ofs < 0) || (len < 0) || (ofs > out.length - len)) {
throw new DigestException("Buffer too short to store digest");
}
if (bytesProcessed < 0) {
engineReset();
}
implDigest(out, ofs);
bytesProcessed = -1;
return digestLength;
}
/**
* Core compression function. Processes blockSize bytes at a time
* and updates the state of this object.
*/
abstract void implCompress(byte[] b, int ofs);
/**
* Return the digest. Subclasses do not need to reset() themselves,
* DigestBase calls implReset() when necessary.
*/
abstract void implDigest(byte[] out, int ofs);
/**
* Reset subclass specific state to their initial values. DigestBase
* calls this method when necessary.
*/
abstract void implReset();
/**
* Clone this digest. Should be implemented as "return new MyDigest(this)".
* That constructor should first call "super(baseDigest)" and then copy
* subclass specific data.
*/
public abstract Object clone();
// padding used for the MD5, and SHA-* message digests
static final byte[] padding;
static {
// we need 128 byte padding for SHA-384/512
// and an additional 8 bytes for the high 8 bytes of the 16
// byte bit counter in SHA-384/512
padding = new byte[136];
padding[0] = (byte)0x80;
}
}