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IESEngine.javaAPI DocAzureus 3.0.3.47335Mon Mar 20 04:56:46 GMT 2006org.bouncycastle.crypto.engines

IESEngine

public class IESEngine extends Object
support class for constructing intergrated encryption ciphers for doing basic message exchanges on top of key agreement ciphers

Fields Summary
org.bouncycastle.crypto.BasicAgreement
agree
org.bouncycastle.crypto.DerivationFunction
kdf
org.bouncycastle.crypto.Mac
mac
org.bouncycastle.crypto.BufferedBlockCipher
cipher
byte[]
macBuf
boolean
forEncryption
org.bouncycastle.crypto.CipherParameters
privParam
org.bouncycastle.crypto.CipherParameters
pubParam
org.bouncycastle.crypto.params.IESParameters
param
Constructors Summary
public IESEngine(org.bouncycastle.crypto.BasicAgreement agree, org.bouncycastle.crypto.DerivationFunction kdf, org.bouncycastle.crypto.Mac mac)
set up for use with stream mode, where the key derivation function is used to provide a stream of bytes to xor with the message.

param
agree the key agreement used as the basis for the encryption
param
kdf the key derivation function used for byte generation
param
mac the message authentication code generator for the message

        this.agree = agree;
        this.kdf = kdf;
        this.mac = mac;
        this.macBuf = new byte[mac.getMacSize()];
        this.cipher = null;
public IESEngine(org.bouncycastle.crypto.BasicAgreement agree, org.bouncycastle.crypto.DerivationFunction kdf, org.bouncycastle.crypto.Mac mac, org.bouncycastle.crypto.BufferedBlockCipher cipher)
set up for use in conjunction with a block cipher to handle the message.

param
agree the key agreement used as the basis for the encryption
param
kdf the key derivation function used for byte generation
param
mac the message authentication code generator for the message
param
cipher the cipher to used for encrypting the message

        this.agree = agree;
        this.kdf = kdf;
        this.mac = mac;
        this.macBuf = new byte[mac.getMacSize()];
        this.cipher = cipher;
Methods Summary
private byte[]decryptBlock(byte[] in_enc, int inOff, int inLen, byte[] z)

        byte[]          M = null;
        KeyParameter    macKey = null;
        KDFParameters   kParam = new KDFParameters(z, param.getDerivationV());
        int             macKeySize = param.getMacKeySize();

        kdf.init(kParam);

	    inLen -= mac.getMacSize();
	
        if (cipher == null)     // stream mode
        {
            byte[]  buf = new byte[inLen + (macKeySize / 8)];

            M = new byte[inLen];

            kdf.generateBytes(buf, 0, buf.length);

            for (int i = 0; i != inLen; i++)
            {
                M[i] = (byte)(in_enc[inOff + i] ^ buf[i]);
            }

            macKey = new KeyParameter(buf, inLen, (macKeySize / 8));
        }
        else
        {
            int     cipherKeySize = ((IESWithCipherParameters)param).getCipherKeySize();
            byte[]  buf = new byte[(cipherKeySize / 8) + (macKeySize / 8)];

            cipher.init(false, new KeyParameter(buf, 0, (cipherKeySize / 8)));

            byte[] tmp = new byte[cipher.getOutputSize(inLen)];

            int off = cipher.processBytes(in_enc, inOff, inLen, tmp, 0);

            off += cipher.doFinal(tmp, off);

            M = new byte[off];

            System.arraycopy(tmp, 0, M, 0, off);

            macKey = new KeyParameter(buf, (cipherKeySize / 8), (macKeySize / 8));
        }

        byte[]  macIV = param.getEncodingV();

        mac.init(macKey);
        mac.update(in_enc, inOff, inLen);
        mac.update(macIV, 0, macIV.length);
	    mac.doFinal(macBuf, 0);
	
        inOff += inLen;

        for (int t = 0; t < macBuf.length; t++)
	    {	       
            if (macBuf[t] != in_enc[inOff + t])
		    {
			    throw (new InvalidCipherTextException("Mac codes failed to equal."));
		    }
	    }
	   
        return M;
private byte[]encryptBlock(byte[] in, int inOff, int inLen, byte[] z)

        byte[]          C = null;
        KeyParameter    macKey = null;
        KDFParameters   kParam = new KDFParameters(z, param.getDerivationV());
	    int             c_text_length = 0;
        int             macKeySize = param.getMacKeySize();

        kdf.init(kParam);

        if (cipher == null)     // stream mode
        {
            byte[]  buf = new byte[inLen + (macKeySize / 8)];

            C = new byte[inLen + mac.getMacSize()];
	        c_text_length = inLen;

            kdf.generateBytes(buf, 0, buf.length);

            for (int i = 0; i != inLen; i++)
            {
                C[i] = (byte)(in[inOff + i] ^ buf[i]);
            }

            macKey = new KeyParameter(buf, inLen, (macKeySize / 8));
        }
        else
        {
            int     cipherKeySize = ((IESWithCipherParameters)param).getCipherKeySize();
            byte[]  buf = new byte[(cipherKeySize / 8) + (macKeySize / 8)];

            cipher.init(true, new KeyParameter(buf, 0, (cipherKeySize / 8)));

            c_text_length = cipher.getOutputSize(inLen);

            C = new byte[c_text_length + mac.getMacSize()];

            int off = cipher.processBytes(in, inOff, inLen, C, 0);

            cipher.doFinal(C, off);

            macKey = new KeyParameter(buf, (cipherKeySize / 8), (macKeySize / 8));
        }

        byte[]  macIV = param.getEncodingV();

        mac.init(macKey);
        mac.update(C, 0, c_text_length);
        mac.update(macIV, 0, macIV.length);
        //
        // return the message and it's MAC
        //
        mac.doFinal(C, c_text_length);
        return C;
public voidinit(boolean forEncryption, org.bouncycastle.crypto.CipherParameters privParam, org.bouncycastle.crypto.CipherParameters pubParam, org.bouncycastle.crypto.CipherParameters param)
Initialise the encryptor.

param
forEncryption whether or not this is encryption/decryption.
param
privParam our private key parameters
param
pubParam the recipient's/sender's public key parameters
param
param encoding and derivation parameters.

        this.forEncryption = forEncryption;
        this.privParam = privParam;
        this.pubParam = pubParam;
        this.param = (IESParameters)param;
public byte[]processBlock(byte[] in, int inOff, int inLen)

        agree.init(privParam);

        BigInteger  z = agree.calculateAgreement(pubParam);

        if (forEncryption)
        {
            return encryptBlock(in, inOff, inLen, z.toByteArray());
        }
        else
        {
            return decryptBlock(in, inOff, inLen, z.toByteArray());
        }