Java example source code file (WrapToken.java)
The WrapToken.java Java example source code
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* accompanied this code).
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package sun.security.jgss.krb5;
import org.ietf.jgss.*;
import sun.security.jgss.*;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.io.ByteArrayOutputStream;
import sun.security.krb5.Confounder;
/**
* This class represents a token emitted by the GSSContext.wrap()
* call. It is a MessageToken except that it also contains plaintext
* or encrypted data at the end. A wrapToken has certain other rules
* that are peculiar to it and different from a MICToken, which is
* another type of MessageToken. All data in a WrapToken is prepended
* by a random counfounder of 8 bytes. All data in a WrapToken is
* also padded with one to eight bytes where all bytes are equal in
* value to the number of bytes being padded. Thus, all application
* data is replaced by (confounder || data || padding).
*
* @author Mayank Upadhyay
*/
class WrapToken extends MessageToken {
/**
* The size of the random confounder used in a WrapToken.
*/
static final int CONFOUNDER_SIZE = 8;
/*
* The padding used with a WrapToken. All data is padded to the
* next multiple of 8 bytes, even if its length is already
* multiple of 8.
* Use this table as a quick way to obtain padding bytes by
* indexing it with the number of padding bytes required.
*/
static final byte[][] pads = {
null, // No, no one escapes padding
{0x01},
{0x02, 0x02},
{0x03, 0x03, 0x03},
{0x04, 0x04, 0x04, 0x04},
{0x05, 0x05, 0x05, 0x05, 0x05},
{0x06, 0x06, 0x06, 0x06, 0x06, 0x06},
{0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07},
{0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08}
};
/*
* A token may come in either in an InputStream or as a
* byte[]. Store a reference to it in either case and process
* it's data only later when getData() is called and
* decryption/copying is needed to be done. Note that JCE can
* decrypt both from a byte[] and from an InputStream.
*/
private boolean readTokenFromInputStream = true;
private InputStream is = null;
private byte[] tokenBytes = null;
private int tokenOffset = 0;
private int tokenLen = 0;
/*
* Application data may come from an InputStream or from a
* byte[]. However, it will always be stored and processed as a
* byte[] since
* (a) the MessageDigest class only accepts a byte[] as input and
* (b) It allows writing to an OuputStream via a CipherOutputStream.
*/
private byte[] dataBytes = null;
private int dataOffset = 0;
private int dataLen = 0;
// the len of the token data: (confounder || data || padding)
private int dataSize = 0;
// Accessed by CipherHelper
byte[] confounder = null;
byte[] padding = null;
private boolean privacy = false;
/**
* Constructs a WrapToken from token bytes obtained from the
* peer.
* @param context the mechanism context associated with this
* token
* @param tokenBytes the bytes of the token
* @param tokenOffset the offset of the token
* @param tokenLen the length of the token
* @param prop the MessageProp into which characteristics of the
* parsed token will be stored.
* @throws GSSException if the token is defective
*/
public WrapToken(Krb5Context context,
byte[] tokenBytes, int tokenOffset, int tokenLen,
MessageProp prop) throws GSSException {
// Just parse the MessageToken part first
super(Krb5Token.WRAP_ID, context,
tokenBytes, tokenOffset, tokenLen, prop);
this.readTokenFromInputStream = false;
// Will need the token bytes again when extracting data
this.tokenBytes = tokenBytes;
this.tokenOffset = tokenOffset;
this.tokenLen = tokenLen;
this.privacy = prop.getPrivacy();
dataSize =
getGSSHeader().getMechTokenLength() - getKrb5TokenSize();
}
/**
* Constructs a WrapToken from token bytes read on the fly from
* an InputStream.
* @param context the mechanism context associated with this
* token
* @param is the InputStream containing the token bytes
* @param prop the MessageProp into which characteristics of the
* parsed token will be stored.
* @throws GSSException if the token is defective or if there is
* a problem reading from the InputStream
*/
public WrapToken(Krb5Context context,
InputStream is, MessageProp prop)
throws GSSException {
// Just parse the MessageToken part first
super(Krb5Token.WRAP_ID, context, is, prop);
// Will need the token bytes again when extracting data
this.is = is;
this.privacy = prop.getPrivacy();
/*
debug("WrapToken Cons: gssHeader.getMechTokenLength=" +
getGSSHeader().getMechTokenLength());
debug("\n token size="
+ getTokenSize());
*/
dataSize =
getGSSHeader().getMechTokenLength() - getTokenSize();
// debug("\n dataSize=" + dataSize);
// debug("\n");
}
/**
* Obtains the application data that was transmitted in this
* WrapToken.
* @return a byte array containing the application data
* @throws GSSException if an error occurs while decrypting any
* cipher text and checking for validity
*/
public byte[] getData() throws GSSException {
byte[] temp = new byte[dataSize];
getData(temp, 0);
// Remove the confounder and the padding
byte[] retVal = new byte[dataSize - confounder.length -
padding.length];
System.arraycopy(temp, 0, retVal, 0, retVal.length);
return retVal;
}
/**
* Obtains the application data that was transmitted in this
* WrapToken, writing it into an application provided output
* array.
* @param dataBuf the output buffer into which the data must be
* written
* @param dataBufOffset the offset at which to write the data
* @return the size of the data written
* @throws GSSException if an error occurs while decrypting any
* cipher text and checking for validity
*/
public int getData(byte[] dataBuf, int dataBufOffset)
throws GSSException {
if (readTokenFromInputStream)
getDataFromStream(dataBuf, dataBufOffset);
else
getDataFromBuffer(dataBuf, dataBufOffset);
return (dataSize - confounder.length - padding.length);
}
/**
* Helper routine to obtain the application data transmitted in
* this WrapToken. It is called if the WrapToken was constructed
* with a byte array as input.
* @param dataBuf the output buffer into which the data must be
* written
* @param dataBufOffset the offset at which to write the data
* @throws GSSException if an error occurs while decrypting any
* cipher text and checking for validity
*/
private void getDataFromBuffer(byte[] dataBuf, int dataBufOffset)
throws GSSException {
GSSHeader gssHeader = getGSSHeader();
int dataPos = tokenOffset +
gssHeader.getLength() + getTokenSize();
if (dataPos + dataSize > tokenOffset + tokenLen)
throw new GSSException(GSSException.DEFECTIVE_TOKEN, -1,
"Insufficient data in "
+ getTokenName(getTokenId()));
// debug("WrapToken cons: data is token is [" +
// getHexBytes(tokenBytes, tokenOffset, tokenLen) + "]\n");
confounder = new byte[CONFOUNDER_SIZE];
// Do decryption if this token was privacy protected.
if (privacy) {
cipherHelper.decryptData(this,
tokenBytes, dataPos, dataSize, dataBuf, dataBufOffset);
/*
debug("\t\tDecrypted data is [" +
getHexBytes(confounder) + " " +
getHexBytes(dataBuf, dataBufOffset,
dataSize - CONFOUNDER_SIZE - padding.length) +
getHexBytes(padding) +
"]\n");
*/
} else {
// Token data is in cleartext
// debug("\t\tNo encryption was performed by peer.\n");
System.arraycopy(tokenBytes, dataPos,
confounder, 0, CONFOUNDER_SIZE);
int padSize = tokenBytes[dataPos + dataSize - 1];
if (padSize < 0)
padSize = 0;
if (padSize > 8)
padSize %= 8;
padding = pads[padSize];
// debug("\t\tPadding applied was: " + padSize + "\n");
System.arraycopy(tokenBytes, dataPos + CONFOUNDER_SIZE,
dataBuf, dataBufOffset, dataSize -
CONFOUNDER_SIZE - padSize);
// byte[] debugbuf = new byte[dataSize - CONFOUNDER_SIZE - padSize];
// System.arraycopy(tokenBytes, dataPos + CONFOUNDER_SIZE,
// debugbuf, 0, debugbuf.length);
// debug("\t\tData is: " + getHexBytes(debugbuf, debugbuf.length));
}
/*
* Make sure sign and sequence number are not corrupt
*/
if (!verifySignAndSeqNumber(confounder,
dataBuf, dataBufOffset,
dataSize - CONFOUNDER_SIZE
- padding.length,
padding))
throw new GSSException(GSSException.BAD_MIC, -1,
"Corrupt checksum or sequence number in Wrap token");
}
/**
* Helper routine to obtain the application data transmitted in
* this WrapToken. It is called if the WrapToken was constructed
* with an Inputstream.
* @param dataBuf the output buffer into which the data must be
* written
* @param dataBufOffset the offset at which to write the data
* @throws GSSException if an error occurs while decrypting any
* cipher text and checking for validity
*/
private void getDataFromStream(byte[] dataBuf, int dataBufOffset)
throws GSSException {
GSSHeader gssHeader = getGSSHeader();
// Don't check the token length. Data will be read on demand from
// the InputStream.
// debug("WrapToken cons: data will be read from InputStream.\n");
confounder = new byte[CONFOUNDER_SIZE];
try {
// Do decryption if this token was privacy protected.
if (privacy) {
cipherHelper.decryptData(this, is, dataSize,
dataBuf, dataBufOffset);
// debug("\t\tDecrypted data is [" +
// getHexBytes(confounder) + " " +
// getHexBytes(dataBuf, dataBufOffset,
// dataSize - CONFOUNDER_SIZE - padding.length) +
// getHexBytes(padding) +
// "]\n");
} else {
// Token data is in cleartext
// debug("\t\tNo encryption was performed by peer.\n");
readFully(is, confounder);
if (cipherHelper.isArcFour()) {
padding = pads[1];
readFully(is, dataBuf, dataBufOffset, dataSize-CONFOUNDER_SIZE-1);
} else {
// Data is always a multiple of 8 with this GSS Mech
// Copy all but last block as they are
int numBlocks = (dataSize - CONFOUNDER_SIZE)/8 - 1;
int offset = dataBufOffset;
for (int i = 0; i < numBlocks; i++) {
readFully(is, dataBuf, offset, 8);
offset += 8;
}
byte[] finalBlock = new byte[8];
readFully(is, finalBlock);
int padSize = finalBlock[7];
padding = pads[padSize];
// debug("\t\tPadding applied was: " + padSize + "\n");
System.arraycopy(finalBlock, 0, dataBuf, offset,
finalBlock.length - padSize);
}
}
} catch (IOException e) {
throw new GSSException(GSSException.DEFECTIVE_TOKEN, -1,
getTokenName(getTokenId())
+ ": " + e.getMessage());
}
/*
* Make sure sign and sequence number are not corrupt
*/
if (!verifySignAndSeqNumber(confounder,
dataBuf, dataBufOffset,
dataSize - CONFOUNDER_SIZE
- padding.length,
padding))
throw new GSSException(GSSException.BAD_MIC, -1,
"Corrupt checksum or sequence number in Wrap token");
}
/**
* Helper routine to pick the right padding for a certain length
* of application data. Every application message has some
* padding between 1 and 8 bytes.
* @param len the length of the application data
* @return the padding to be applied
*/
private byte[] getPadding(int len) {
int padSize = 0;
// For RC4-HMAC, all padding is rounded up to 1 byte.
// One byte is needed to say that there is 1 byte of padding.
if (cipherHelper.isArcFour()) {
padSize = 1;
} else {
padSize = len % 8;
padSize = 8 - padSize;
}
return pads[padSize];
}
public WrapToken(Krb5Context context, MessageProp prop,
byte[] dataBytes, int dataOffset, int dataLen)
throws GSSException {
super(Krb5Token.WRAP_ID, context);
confounder = Confounder.bytes(CONFOUNDER_SIZE);
padding = getPadding(dataLen);
dataSize = confounder.length + dataLen + padding.length;
this.dataBytes = dataBytes;
this.dataOffset = dataOffset;
this.dataLen = dataLen;
/*
debug("\nWrapToken cons: data to wrap is [" +
getHexBytes(confounder) + " " +
getHexBytes(dataBytes, dataOffset, dataLen) + " " +
// padding is never null for Wrap
getHexBytes(padding) + "]\n");
*/
genSignAndSeqNumber(prop,
confounder,
dataBytes, dataOffset, dataLen,
padding);
/*
* If the application decides to ask for privacy when the context
* did not negotiate for it, do not provide it. The peer might not
* have support for it. The app will realize this with a call to
* pop.getPrivacy() after wrap().
*/
if (!context.getConfState())
prop.setPrivacy(false);
privacy = prop.getPrivacy();
}
public void encode(OutputStream os) throws IOException, GSSException {
super.encode(os);
// debug("Writing data: [");
if (!privacy) {
// debug(getHexBytes(confounder, confounder.length));
os.write(confounder);
// debug(" " + getHexBytes(dataBytes, dataOffset, dataLen));
os.write(dataBytes, dataOffset, dataLen);
// debug(" " + getHexBytes(padding, padding.length));
os.write(padding);
} else {
cipherHelper.encryptData(this, confounder,
dataBytes, dataOffset, dataLen, padding, os);
}
// debug("]\n");
}
public byte[] encode() throws IOException, GSSException {
// XXX Fine tune this initial size
ByteArrayOutputStream bos = new ByteArrayOutputStream(dataSize + 50);
encode(bos);
return bos.toByteArray();
}
public int encode(byte[] outToken, int offset)
throws IOException, GSSException {
// Token header is small
ByteArrayOutputStream bos = new ByteArrayOutputStream();
super.encode(bos);
byte[] header = bos.toByteArray();
System.arraycopy(header, 0, outToken, offset, header.length);
offset += header.length;
// debug("WrapToken.encode: Writing data: [");
if (!privacy) {
// debug(getHexBytes(confounder, confounder.length));
System.arraycopy(confounder, 0, outToken, offset,
confounder.length);
offset += confounder.length;
// debug(" " + getHexBytes(dataBytes, dataOffset, dataLen));
System.arraycopy(dataBytes, dataOffset, outToken, offset,
dataLen);
offset += dataLen;
// debug(" " + getHexBytes(padding, padding.length));
System.arraycopy(padding, 0, outToken, offset, padding.length);
} else {
cipherHelper.encryptData(this, confounder, dataBytes,
dataOffset, dataLen, padding, outToken, offset);
// debug(getHexBytes(outToken, offset, dataSize));
}
// debug("]\n");
// %%% assume that plaintext length == ciphertext len
return (header.length + confounder.length + dataLen + padding.length);
}
protected int getKrb5TokenSize() throws GSSException {
return (getTokenSize() + dataSize);
}
protected int getSealAlg(boolean conf, int qop) throws GSSException {
if (!conf) {
return SEAL_ALG_NONE;
}
// ignore QOP
return cipherHelper.getSealAlg();
}
// This implementation is way too conservative. And it certainly
// doesn't return the maximum limit.
static int getSizeLimit(int qop, boolean confReq, int maxTokenSize,
CipherHelper ch) throws GSSException {
return (GSSHeader.getMaxMechTokenSize(OID, maxTokenSize) -
(getTokenSize(ch) + CONFOUNDER_SIZE) - 8); /* safety */
}
}
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