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[Cryptix-users] Decoding
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From: Aredeji D. <ar...@ho...> - 2006-08-09 17:01:21
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I was unable to decode PGP files encrypted with multiple keys. Only one of
the private keys would work during the decryption. The following code seems
to be a part of the problem.
public class PGPDecodedMessageInputStream
public void engineInit(InputStream in,
DecryptionKeyCallback dkc, VerificationKeyCallback vkc)
line 191: while (it.hasNext()) {
PGPPublicKey pubsubkey =
(PGPPublicKey)it.next();
PGPPrivateKey privsubkey;
try {
privsubkey = (PGPPrivateKey)
pgpbundle.getPrivateSubKey(
pubsubkey, val.getPassphrase());
PGPEncryptor cryptor = (PGPEncryptor)
privsubkey.getPacket().getAlgorithm();
for (int i=0; i<sessionkeys.size(); i++) {
if (sessionkeys.elementAt(i) instanceof
PGPPublicKeyEncryptedSessionKeyPacket)
{
PGPPublicKeyEncryptedSessionKeyPacket
pkeskp =
(PGPPublicKeyEncryptedSessionKeyPacket)
sessionkeys.elementAt(i);
boolean success = false;
pkeskp.decrypt(cryptor);
success = true;
if (success) {
decryptkey =
pkeskp.getSessionKey();
}
}
}
} catch (UnrecoverableKeyException uke) {
} catch (PGPDataFormatException e) {
} catch (PGPDecryptionFailedException e) {
}
I have changed the above code to:
while (it.hasNext()) {
PGPPublicKey pubsubkey =
(PGPPublicKey)it.next();
PGPPrivateKey privsubkey;
try {
privsubkey = (PGPPrivateKey)
pgpbundle.getPrivateSubKey(
pubsubkey, val.getPassphrase());
PGPEncryptor cryptor = (PGPEncryptor)
privsubkey.getPacket().getAlgorithm();
KeyIDFactory kidf =
KeyIDFactory.getInstance(PGPConstants.OPENPGP);
KeyID kID_Decrypt =
kidf.generateKeyID((PublicKey)pubsubkey);
for (int i=0; i<sessionkeys.size(); i++) {
if (sessionkeys.elementAt(i) instanceof
PGPPublicKeyEncryptedSessionKeyPacket)
{
PGPPublicKeyEncryptedSessionKeyPacket
pkeskp =
(PGPPublicKeyEncryptedSessionKeyPacket)
sessionkeys.elementAt(i);
boolean success = false;
if((PGPHex.toString(pkeskp.getKeyID())).equals(PGPHex.toString(kID_Decrypt.getBytes(8))))
{
pkeskp.decrypt(cryptor);
success = true;
}
if (success) {
decryptkey =
pkeskp.getSessionKey();
}
}
}
} catch (UnrecoverableKeyException uke) {
} catch (PGPDataFormatException e) {
} catch (PGPDecryptionFailedException e) {
} catch (NoSuchAlgorithmException e) {
} catch (InvalidKeyException e) {
}
}
It seems to be working now. I can decode files encrypted with multiple keys.
I was also unable to decode PGP files of certain size. I changed the
following code
public int read(byte[] b, int off, int len)
throws IOException
{
try {
if (buf.length - bufoffset >= len) {
System.arraycopy(buf, bufoffset, b, 0, len);
if (mdc != null) mdc.update(b, 0, len);
bufoffset += len;
return len;
}
byte[] temp;
if (in.available() > 32) {
temp = new byte[(int)in.available() & 0xffffffe0];
if (temp.length < len+blocksize*2+2)
temp = new byte[len+blocksize*2+2];
} else {
temp = new byte[len+blocksize*2+2];
}
if ((in.available() == 0) && (buf.length - bufoffset == 0))
return 0;
int size = in.readBuffer(temp);
byte[] data;
if (size < temp.length) {
try {
data = cipher.doFinal(temp, 0, size);
} catch (IllegalBlockSizeException ibse) {
throw new IOException(""+ibse);
} catch (BadPaddingException bpe) {
throw new IOException(""+bpe);
}
} else {
data = cipher.update(temp, 0, size);
}
size = 0;
if (bufoffset < buf.length) {
System.arraycopy(buf, bufoffset, b, off,
buf.length-bufoffset);
size += buf.length-bufoffset;
}
if (size + data.length > len) {
System.arraycopy(data, 0, b, off+size, len-size);
int newbuflen = data.length-(len-size);
buf = new byte[newbuflen];
System.arraycopy(data, len-size, buf, 0, newbuflen);
bufoffset = 0;
if (mdc != null) mdc.update(b, 0, len);
return len;
} else {
System.arraycopy(data, 0, b, off+size, data.length);
bufoffset = buf.length;
if (mdc != null) mdc.update(b, 0, size + data.length);
return size + data.length;
}
} catch (PGPDataFormatException pdfe) {
throw new IOException(""+pdfe);
} catch (PGPFatalDataFormatException pdfe) {
throw new IOException(""+pdfe);
}
}
to
public int read(byte[] b, int off, int len)
throws IOException
{
try {
if (buf.length - bufoffset >= len)
{
System.arraycopy(buf, bufoffset, b, 0, len);
if (mdc != null) mdc.update(b, 0, len);
bufoffset += len;
return len;
}
byte[] temp;
if (in.available() > 32)
{
temp = new byte[(int)in.available() & 0xffffffe0];
if (temp.length < len+blocksize*2+2)
temp = new byte[len+blocksize*2+2];
}
else
{
temp = new byte[len+blocksize*2+2];
//FIXME
if(temp.length == in.available())
{
temp = new byte [temp.length * 2];
}
}
if ((in.available() == 0) && (buf.length - bufoffset == 0))
{
return 0;
}
int size = in.readBuffer(temp);
byte[] data;
if (size < temp.length)
{
try
{
data = cipher.doFinal(temp, 0, size);
}
catch (IllegalBlockSizeException ibse)
{
throw new IOException(""+ibse);
}
catch (BadPaddingException bpe)
{
throw new IOException(""+bpe);
}
}
else
{
data = cipher.update(temp, 0, size);
}
size = 0;
if (bufoffset < buf.length)
{
System.arraycopy(buf, bufoffset, b, off,
buf.length-bufoffset);
size += buf.length-bufoffset;
}
if (size + data.length > len)
{
System.arraycopy(data, 0, b, off+size, len-size);
int newbuflen = data.length-(len-size);
buf = new byte[newbuflen];
System.arraycopy(data, len-size, buf, 0, newbuflen);
bufoffset = 0;
if (mdc != null) mdc.update(b, 0, len);
return len;
}
else
{
System.arraycopy(data, 0, b, off+size, data.length);
bufoffset = buf.length;
if (mdc != null) mdc.update(b, 0, size + data.length);
return size + data.length;
}
}
catch (PGPDataFormatException pdfe)
{
throw new IOException(""+pdfe);
}
catch (PGPFatalDataFormatException pdfe)
{
throw new IOException(""+pdfe);
}
}
Please let me know what permanent changes can be made to ensure successful
decoding.
Best wishes,
Ared
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