Java example source code file (DkCrypto.java)
The DkCrypto.java Java example source code/*
* Copyright (c) 2004, 2007, Oracle and/or its affiliates. All rights reserved.
*/
/*
* Copyright (C) 1998 by the FundsXpress, INC.
*
* All rights reserved.
*
* Export of this software from the United States of America may require
* a specific license from the United States Government. It is the
* responsibility of any person or organization contemplating export to
* obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of FundsXpress. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. FundsXpress makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
package sun.security.krb5.internal.crypto.dk;
import javax.crypto.Cipher;
import javax.crypto.Mac;
import java.security.GeneralSecurityException;
import java.io.UnsupportedEncodingException;
import java.util.Arrays;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.nio.charset.Charset;
import java.nio.CharBuffer;
import java.nio.ByteBuffer;
import sun.misc.HexDumpEncoder;
import sun.security.krb5.Confounder;
import sun.security.krb5.internal.crypto.KeyUsage;
import sun.security.krb5.KrbCryptoException;
/**
* Implements Derive Key cryptography functionality as defined in RFC 3961.
* http://www.ietf.org/rfc/rfc3961.txt
*
* This is an abstract class. Concrete subclasses need to implement
* the abstract methods.
*/
public abstract class DkCrypto {
protected static final boolean debug = false;
// These values correspond to the ASCII encoding for the string "kerberos"
static final byte[] KERBEROS_CONSTANT =
{0x6b, 0x65, 0x72, 0x62, 0x65, 0x72, 0x6f, 0x73};
protected abstract int getKeySeedLength(); // in bits
protected abstract byte[] randomToKey(byte[] in);
protected abstract Cipher getCipher(byte[] key, byte[] ivec, int mode)
throws GeneralSecurityException;
public abstract int getChecksumLength(); // in bytes
protected abstract byte[] getHmac(byte[] key, byte[] plaintext)
throws GeneralSecurityException;
/**
* From RFC 3961.
*
* encryption function conf = random string of length c
* pad = shortest string to bring confounder
* and plaintext to a length that's a
* multiple of m
* (C1, newIV) = E(Ke, conf | plaintext | pad,
* oldstate.ivec)
* H1 = HMAC(Ki, conf | plaintext | pad)
* ciphertext = C1 | H1[1..h]
* newstate.ivec = newIV
*
* @param ivec initial vector to use when initializing the cipher; if null,
* then blocksize number of zeros are used,
* @param new_ivec if non-null, it is updated upon return to be the
* new ivec to use when calling encrypt next time
*/
public byte[] encrypt(byte[] baseKey, int usage,
byte[] ivec, byte[] new_ivec, byte[] plaintext, int start, int len)
throws GeneralSecurityException, KrbCryptoException {
if (!KeyUsage.isValid(usage)) {
throw new GeneralSecurityException("Invalid key usage number: "
+ usage);
}
byte[] Ke = null;
byte[] Ki = null;
try {
// Derive encryption key
byte[] constant = new byte[5];
constant[0] = (byte) ((usage>>24)&0xff);
constant[1] = (byte) ((usage>>16)&0xff);
constant[2] = (byte) ((usage>>8)&0xff);
constant[3] = (byte) (usage&0xff);
constant[4] = (byte) 0xaa;
Ke = dk(baseKey, constant);
if (debug) {
System.err.println("usage: " + usage);
if (ivec != null) {
traceOutput("old_state.ivec", ivec, 0, ivec.length);
}
traceOutput("plaintext", plaintext, start, Math.min(len, 32));
traceOutput("constant", constant, 0, constant.length);
traceOutput("baseKey", baseKey, 0, baseKey.length);
traceOutput("Ke", Ke, 0, Ke.length);
}
// Encrypt
// C1 = E(Ke, conf | plaintext | pad, oldivec)
Cipher encCipher = getCipher(Ke, ivec, Cipher.ENCRYPT_MODE);
int blockSize = encCipher.getBlockSize();
byte[] confounder = Confounder.bytes(blockSize);
int plainSize = roundup(confounder.length + len, blockSize);
if (debug) {
System.err.println("confounder = " + confounder.length +
"; plaintext = " + len + "; padding = " +
(plainSize - confounder.length - len) + "; total = " +
plainSize);
traceOutput("confounder", confounder, 0, confounder.length);
}
byte[] toBeEncrypted = new byte[plainSize];
System.arraycopy(confounder, 0, toBeEncrypted,
0, confounder.length);
System.arraycopy(plaintext, start, toBeEncrypted,
confounder.length, len);
// Set padding bytes to zero
Arrays.fill(toBeEncrypted, confounder.length + len, plainSize,
(byte)0);
int cipherSize = encCipher.getOutputSize(plainSize);
int ccSize = cipherSize + getChecksumLength(); // cipher | hmac
byte[] ciphertext = new byte[ccSize];
encCipher.doFinal(toBeEncrypted, 0, plainSize, ciphertext, 0);
// Update ivec for next operation
// (last blockSize bytes of ciphertext)
// newstate.ivec = newIV
if (new_ivec != null && new_ivec.length == blockSize) {
System.arraycopy(ciphertext, cipherSize - blockSize,
new_ivec, 0, blockSize);
if (debug) {
traceOutput("new_ivec", new_ivec, 0, new_ivec.length);
}
}
// Derive integrity key
constant[4] = (byte) 0x55;
Ki = dk(baseKey, constant);
if (debug) {
traceOutput("constant", constant, 0, constant.length);
traceOutput("Ki", Ki, 0, Ke.length);
}
// Generate checksum
// H1 = HMAC(Ki, conf | plaintext | pad)
byte[] hmac = getHmac(Ki, toBeEncrypted);
if (debug) {
traceOutput("hmac", hmac, 0, hmac.length);
traceOutput("ciphertext", ciphertext, 0,
Math.min(ciphertext.length, 32));
}
// C1 | H1[1..h]
System.arraycopy(hmac, 0, ciphertext, cipherSize,
getChecksumLength());
return ciphertext;
} finally {
if (Ke != null) {
Arrays.fill(Ke, 0, Ke.length, (byte) 0);
}
if (Ki != null) {
Arrays.fill(Ki, 0, Ki.length, (byte) 0);
}
}
}
/**
* Performs encryption using given key only; does not add
* confounder, padding, or checksum. Incoming data to be encrypted
* assumed to have the correct blocksize.
* Ignore key usage.
*/
public byte[] encryptRaw(byte[] baseKey, int usage,
byte[] ivec, byte[] plaintext, int start, int len)
throws GeneralSecurityException, KrbCryptoException {
if (debug) {
System.err.println("usage: " + usage);
if (ivec != null) {
traceOutput("old_state.ivec", ivec, 0, ivec.length);
}
traceOutput("plaintext", plaintext, start, Math.min(len, 32));
traceOutput("baseKey", baseKey, 0, baseKey.length);
}
// Encrypt
Cipher encCipher = getCipher(baseKey, ivec, Cipher.ENCRYPT_MODE);
int blockSize = encCipher.getBlockSize();
if ((len % blockSize) != 0) {
throw new GeneralSecurityException(
"length of data to be encrypted (" + len +
") is not a multiple of the blocksize (" + blockSize + ")");
}
int cipherSize = encCipher.getOutputSize(len);
byte[] ciphertext = new byte[cipherSize];
encCipher.doFinal(plaintext, 0, len, ciphertext, 0);
return ciphertext;
}
/**
* Decrypts data using specified key and initial vector.
* @param baseKey encryption key to use
* @param ciphertext encrypted data to be decrypted
* @param usage ignored
*/
public byte[] decryptRaw(byte[] baseKey, int usage, byte[] ivec,
byte[] ciphertext, int start, int len)
throws GeneralSecurityException {
if (debug) {
System.err.println("usage: " + usage);
if (ivec != null) {
traceOutput("old_state.ivec", ivec, 0, ivec.length);
}
traceOutput("ciphertext", ciphertext, start, Math.min(len, 32));
traceOutput("baseKey", baseKey, 0, baseKey.length);
}
Cipher decCipher = getCipher(baseKey, ivec, Cipher.DECRYPT_MODE);
int blockSize = decCipher.getBlockSize();
if ((len % blockSize) != 0) {
throw new GeneralSecurityException(
"length of data to be decrypted (" + len +
") is not a multiple of the blocksize (" + blockSize + ")");
}
byte[] decrypted = decCipher.doFinal(ciphertext, start, len);
if (debug) {
traceOutput("decrypted", decrypted, 0,
Math.min(decrypted.length, 32));
}
return decrypted;
}
/**
* @param baseKey key from which keys are to be derived using usage
* @param ciphertext E(Ke, conf | plaintext | padding, ivec) | H1[1..h]
*/
public byte[] decrypt(byte[] baseKey, int usage, byte[] ivec,
byte[] ciphertext, int start, int len) throws GeneralSecurityException {
if (!KeyUsage.isValid(usage)) {
throw new GeneralSecurityException("Invalid key usage number: "
+ usage);
}
byte[] Ke = null;
byte[] Ki = null;
try {
// Derive encryption key
byte[] constant = new byte[5];
constant[0] = (byte) ((usage>>24)&0xff);
constant[1] = (byte) ((usage>>16)&0xff);
constant[2] = (byte) ((usage>>8)&0xff);
constant[3] = (byte) (usage&0xff);
constant[4] = (byte) 0xaa;
Ke = dk(baseKey, constant); // Encryption key
if (debug) {
System.err.println("usage: " + usage);
if (ivec != null) {
traceOutput("old_state.ivec", ivec, 0, ivec.length);
}
traceOutput("ciphertext", ciphertext, start, Math.min(len, 32));
traceOutput("constant", constant, 0, constant.length);
traceOutput("baseKey", baseKey, 0, baseKey.length);
traceOutput("Ke", Ke, 0, Ke.length);
}
Cipher decCipher = getCipher(Ke, ivec, Cipher.DECRYPT_MODE);
int blockSize = decCipher.getBlockSize();
// Decrypt [confounder | plaintext | padding] (without checksum)
int cksumSize = getChecksumLength();
int cipherSize = len - cksumSize;
byte[] decrypted = decCipher.doFinal(ciphertext, start, cipherSize);
if (debug) {
traceOutput("decrypted", decrypted, 0,
Math.min(decrypted.length, 32));
}
// decrypted = [confounder | plaintext | padding]
// Derive integrity key
constant[4] = (byte) 0x55;
Ki = dk(baseKey, constant); // Integrity key
if (debug) {
traceOutput("constant", constant, 0, constant.length);
traceOutput("Ki", Ki, 0, Ke.length);
}
// Verify checksum
// H1 = HMAC(Ki, conf | plaintext | pad)
byte[] calculatedHmac = getHmac(Ki, decrypted);
if (debug) {
traceOutput("calculated Hmac", calculatedHmac, 0,
calculatedHmac.length);
traceOutput("message Hmac", ciphertext, cipherSize,
cksumSize);
}
boolean cksumFailed = false;
if (calculatedHmac.length >= cksumSize) {
for (int i = 0; i < cksumSize; i++) {
if (calculatedHmac[i] != ciphertext[cipherSize+i]) {
cksumFailed = true;
break;
}
}
}
if (cksumFailed) {
throw new GeneralSecurityException("Checksum failed");
}
// Prepare decrypted msg and ivec to be returned
// Last blockSize bytes of ciphertext without checksum
if (ivec != null && ivec.length == blockSize) {
System.arraycopy(ciphertext, start + cipherSize - blockSize,
ivec, 0, blockSize);
if (debug) {
traceOutput("new_state.ivec", ivec, 0, ivec.length);
}
}
// Get rid of confounder
// [plaintext | padding]
byte[] plaintext = new byte[decrypted.length - blockSize];
System.arraycopy(decrypted, blockSize, plaintext,
0, plaintext.length);
return plaintext; // padding still there
} finally {
if (Ke != null) {
Arrays.fill(Ke, 0, Ke.length, (byte) 0);
}
if (Ki != null) {
Arrays.fill(Ki, 0, Ki.length, (byte) 0);
}
}
}
// Round up to the next blocksize
int roundup(int n, int blocksize) {
return (((n + blocksize - 1) / blocksize) * blocksize);
}
public byte[] calculateChecksum(byte[] baseKey, int usage, byte[] input,
int start, int len) throws GeneralSecurityException {
if (!KeyUsage.isValid(usage)) {
throw new GeneralSecurityException("Invalid key usage number: "
+ usage);
}
// Derive keys
byte[] constant = new byte[5];
constant[0] = (byte) ((usage>>24)&0xff);
constant[1] = (byte) ((usage>>16)&0xff);
constant[2] = (byte) ((usage>>8)&0xff);
constant[3] = (byte) (usage&0xff);
constant[4] = (byte) 0x99;
byte[] Kc = dk(baseKey, constant); // Checksum key
if (debug) {
System.err.println("usage: " + usage);
traceOutput("input", input, start, Math.min(len, 32));
traceOutput("constant", constant, 0, constant.length);
traceOutput("baseKey", baseKey, 0, baseKey.length);
traceOutput("Kc", Kc, 0, Kc.length);
}
try {
// Generate checksum
// H1 = HMAC(Kc, input)
byte[] hmac = getHmac(Kc, input);
if (debug) {
traceOutput("hmac", hmac, 0, hmac.length);
}
if (hmac.length == getChecksumLength()) {
return hmac;
} else if (hmac.length > getChecksumLength()) {
byte[] buf = new byte[getChecksumLength()];
System.arraycopy(hmac, 0, buf, 0, buf.length);
return buf;
} else {
throw new GeneralSecurityException("checksum size too short: " +
hmac.length + "; expecting : " + getChecksumLength());
}
} finally {
Arrays.fill(Kc, 0, Kc.length, (byte)0);
}
}
// DK(Key, Constant) = random-to-key(DR(Key, Constant))
byte[] dk(byte[] key, byte[] constant)
throws GeneralSecurityException {
return randomToKey(dr(key, constant));
}
/*
* From RFC 3961.
*
* DR(Key, Constant) = k-truncate(E(Key, Constant,
* initial-cipher-state))
*
* Here DR is the random-octet generation function described below, and
* DK is the key-derivation function produced from it. In this
* construction, E(Key, Plaintext, CipherState) is a cipher, Constant is
* a well-known constant determined by the specific usage of this
* function, and k-truncate truncates its argument by taking the first k
* bits. Here, k is the key generation seed length needed for the
* encryption system.
*
* The output of the DR function is a string of bits; the actual key is
* produced by applying the cryptosystem's random-to-key operation on
* this bitstring.
*
* If the Constant is smaller than the cipher block size of E, then it
* must be expanded with n-fold() so it can be encrypted. If the output
* of E is shorter than k bits it is fed back into the encryption as
* many times as necessary. The construct is as follows (where |
* indicates concatentation):
*
* K1 = E(Key, n-fold(Constant), initial-cipher-state)
* K2 = E(Key, K1, initial-cipher-state)
* K3 = E(Key, K2, initial-cipher-state)
* K4 = ...
*
* DR(Key, Constant) = k-truncate(K1 | K2 | K3 | K4 ...)
*/
private byte[] dr(byte[] key, byte[] constant)
throws GeneralSecurityException {
Cipher encCipher = getCipher(key, null, Cipher.ENCRYPT_MODE);
int blocksize = encCipher.getBlockSize();
if (constant.length != blocksize) {
constant = nfold(constant, blocksize * 8);
}
byte[] toBeEncrypted = constant;
int keybytes = (getKeySeedLength()>>3); // from bits to bytes
byte[] rawkey = new byte[keybytes];
int posn = 0;
/* loop encrypting the blocks until enough key bytes are generated */
int n = 0, len;
while (n < keybytes) {
if (debug) {
System.err.println("Encrypting: " +
bytesToString(toBeEncrypted));
}
byte[] cipherBlock = encCipher.doFinal(toBeEncrypted);
if (debug) {
System.err.println("K: " + ++posn + " = " +
bytesToString(cipherBlock));
}
len = (keybytes - n <= cipherBlock.length ? (keybytes - n) :
cipherBlock.length);
if (debug) {
System.err.println("copying " + len + " key bytes");
}
System.arraycopy(cipherBlock, 0, rawkey, n, len);
n += len;
toBeEncrypted = cipherBlock;
}
return rawkey;
}
// ---------------------------------
// From MIT-1.3.1 distribution
/*
* n-fold(k-bits):
* l = lcm(n,k)
* r = l/k
* s = k-bits | k-bits rot 13 | k-bits rot 13*2 | ... | k-bits rot 13*(r-1)
* compute the 1's complement sum:
* n-fold = s[0..n-1]+s[n..2n-1]+s[2n..3n-1]+..+s[(k-1)*n..k*n-1]
*/
/*
* representation: msb first, assume n and k are multiples of 8, and
* that k>=16. this is the case of all the cryptosystems which are
* likely to be used. this function can be replaced if that
* assumption ever fails.
*/
/* input length is in bits */
static byte[] nfold(byte[] in, int outbits) {
int inbits = in.length;
outbits >>= 3; // count in bytes
/* first compute lcm(n,k) */
int a, b, c, lcm;
a = outbits; // n
b = inbits; // k
while (b != 0) {
c = b;
b = a % b;
a = c;
}
lcm = outbits*inbits/a;
if (debug) {
System.err.println("k: " + inbits);
System.err.println("n: " + outbits);
System.err.println("lcm: " + lcm);
}
/* now do the real work */
byte[] out = new byte[outbits];
Arrays.fill(out, (byte)0);
int thisbyte = 0;
int msbit, i, bval, oval;
// this will end up cycling through k lcm(k,n)/k times, which
// is correct
for (i = lcm-1; i >= 0; i--) {
/* compute the msbit in k which gets added into this byte */
msbit = (/* first, start with msbit in the first, unrotated byte */
((inbits<<3)-1)
/* then, for each byte, shift to right for each repetition */
+ (((inbits<<3)+13)*(i/inbits))
/* last, pick out correct byte within that shifted repetition */
+ ((inbits-(i%inbits)) << 3)) % (inbits << 3);
/* pull out the byte value itself */
// Mask off values using &0xff to get only the lower byte
// Use >>> to avoid sign extension
bval = ((((in[((inbits-1)-(msbit>>>3))%inbits]&0xff)<<8)|
(in[((inbits)-(msbit>>>3))%inbits]&0xff))
>>>((msbit&7)+1))&0xff;
/*
System.err.println("((" +
((in[((inbits-1)-(msbit>>>3))%inbits]&0xff)<<8)
+ "|" + (in[((inbits)-(msbit>>>3))%inbits]&0xff) + ")"
+ ">>>" + ((msbit&7)+1) + ")&0xff = " + bval);
*/
thisbyte += bval;
/* do the addition */
// Mask off values using &0xff to get only the lower byte
oval = (out[i%outbits]&0xff);
thisbyte += oval;
out[i%outbits] = (byte) (thisbyte&0xff);
if (debug) {
System.err.println("msbit[" + i + "] = " + msbit + "\tbval=" +
Integer.toHexString(bval) + "\toval=" +
Integer.toHexString(oval)
+ "\tsum = " + Integer.toHexString(thisbyte));
}
/* keep around the carry bit, if any */
thisbyte >>>= 8;
if (debug) {
System.err.println("carry=" + thisbyte);
}
}
/* if there's a carry bit left over, add it back in */
if (thisbyte != 0) {
for (i = outbits-1; i >= 0; i--) {
/* do the addition */
thisbyte += (out[i]&0xff);
out[i] = (byte) (thisbyte&0xff);
/* keep around the carry bit, if any */
thisbyte >>>= 8;
}
}
return out;
}
// Routines used for debugging
static String bytesToString(byte[] digest) {
// Get character representation of digest
StringBuffer digestString = new StringBuffer();
for (int i = 0; i < digest.length; i++) {
if ((digest[i] & 0x000000ff) < 0x10) {
digestString.append("0" +
Integer.toHexString(digest[i] & 0x000000ff));
} else {
digestString.append(
Integer.toHexString(digest[i] & 0x000000ff));
}
}
return digestString.toString();
}
private static byte[] binaryStringToBytes(String str) {
char[] usageStr = str.toCharArray();
byte[] usage = new byte[usageStr.length/2];
for (int i = 0; i < usage.length; i++) {
byte a = Byte.parseByte(new String(usageStr, i*2, 1), 16);
byte b = Byte.parseByte(new String(usageStr, i*2 + 1, 1), 16);
usage[i] = (byte) ((a<<4)|b);
}
return usage;
}
static void traceOutput(String traceTag, byte[] output, int offset,
int len) {
try {
ByteArrayOutputStream out = new ByteArrayOutputStream(len);
new HexDumpEncoder().encodeBuffer(
new ByteArrayInputStream(output, offset, len), out);
System.err.println(traceTag + ":" + out.toString());
} catch (Exception e) {
}
}
// String.getBytes("UTF-8");
// Do this instead of using String to avoid making password immutable
static byte[] charToUtf8(char[] chars) {
Charset utf8 = Charset.forName("UTF-8");
CharBuffer cb = CharBuffer.wrap(chars);
ByteBuffer bb = utf8.encode(cb);
int len = bb.limit();
byte[] answer = new byte[len];
bb.get(answer, 0, len);
return answer;
}
static byte[] charToUtf16(char[] chars) {
Charset utf8 = Charset.forName("UTF-16LE");
CharBuffer cb = CharBuffer.wrap(chars);
ByteBuffer bb = utf8.encode(cb);
int len = bb.limit();
byte[] answer = new byte[len];
bb.get(answer, 0, len);
return answer;
}
}
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