package railo.runtime.security;
import java.util.Random;
import railo.runtime.crypt.BinConverter;
import railo.runtime.crypt.BlowfishCBC;
import railo.runtime.crypt.BlowfishECB;
import railo.runtime.crypt.SHA1;
/**
* support class for easy string encryption with the Blowfish algorithm,
* now in CBC mode with a SHA-1 key setup and correct padding
*/
public final class SerialDecoder {
BlowfishCBC m_bfish;
// one random generator for all simple callers...
static Random m_rndGen;
// ...and created early
static {
m_rndGen = new Random();
};
/**
* constructor to set up a string as the key (oversized password will be cut)
* @param sPassword the password (treated as a real unicode array)
*/
public SerialDecoder(String sPassword) {
// hash down the password to a 160bit key
SHA1 hasher = new SHA1();
hasher.update(sPassword);
hasher.finalize();
// setup the encryptor (use a dummy IV)
m_bfish = new BlowfishCBC(hasher.getDigest(), 0);
hasher.clear();
};
/**
* decrypts a hexbin string (handling is case sensitive)
* @param sCipherText hexbin string to decrypt
* @return decrypted string (null equals an error)
*/
public String decrypt(String sCipherText) {
// get the number of estimated bytes in the string (cut off broken blocks)
int nLen = (sCipherText.length() >> 1) & ~7;
// does the given stuff make sense (at least the CBC IV)?
if (nLen < BlowfishECB.BLOCKSIZE)
return null;
// get the CBC IV
byte[] cbciv = new byte[BlowfishECB.BLOCKSIZE];
int nNumOfBytes = BinConverter.binHexToBytes(sCipherText,
cbciv,
0,
0,
BlowfishECB.BLOCKSIZE);
if (nNumOfBytes < BlowfishECB.BLOCKSIZE)
return null;
// (got it)
m_bfish.setCBCIV(cbciv);
// something left to decrypt?
nLen -= BlowfishECB.BLOCKSIZE;
if (nLen == 0)
return "";
// get all data bytes now
byte[] buf = new byte[nLen];
nNumOfBytes = BinConverter.binHexToBytes(sCipherText,
buf,
BlowfishECB.BLOCKSIZE * 2,
0,
nLen);
// we cannot accept broken binhex sequences due to padding
// and decryption
if (nNumOfBytes < nLen)
return null;
// decrypt the buffer
m_bfish.decrypt(buf);
// get the last padding byte
int nPadByte = buf[buf.length - 1] & 0x0ff;
// ( try to get all information if the padding doesn't seem to be correct)
if ((nPadByte > 8) || (nPadByte < 0))
nPadByte = 0;
// calculate the real size of this message
nNumOfBytes -= nPadByte;
if (nNumOfBytes < 0)
return "";
// success
return BinConverter.byteArrayToUNCString(buf, 0, nNumOfBytes);
};
/**
* destroys (clears) the encryption engine,
* after that the instance is not valid anymore
*/
public void destroy() {
m_bfish.cleanUp();
};
};