package security;import jj2000.j2k.codestream.writer.*;import jj2000.j2k.wavelet.synthesis.*;import jj2000.j2k.entropy.decoder.*;import jj2000.j2k.util.*;import cryptix.provider.rsa.*;import java.math.*;import java.util.*;/** Class to retrieve side information found in code-block's bit * stream (i.e. found after a stopping marker). Instances are used * between the codestream reading and the entropy decoding * modules.  */public class SideInfoRetrieval extends MultiResImgDataAdapter    implements CodedCBlkDataSrcDec {    /** Number of code-blocks found so far with embedded     * side-information */    private int numProtectCblk = 0;        /** Reference to the codestream reader */    private CodedCBlkDataSrcDec src;    /** Reference to the ParameterList instance */    private ParameterList pl;    /** RSA public exponent to decrypt seed values */    private BigInteger rsaExp;    /** RSA public modulus to decrypt seed values */    private BigInteger rsaMod;    /** Whether or not current seed is encrypted */    private boolean isEncrypted = false;    public SideInfoRetrieval(CodedCBlkDataSrcDec src,ParameterList pl) {	super(src);	this.src = src;	this.pl = pl;	String str = pl.getParameter("Spublic_key");	if(str!=null) {	    StringTokenizer stk = new StringTokenizer(str);	    if(stk.countTokens()==2) {		rsaExp = new BigInteger(stk.nextToken());		rsaMod = new BigInteger(stk.nextToken());	    }	}    }    /** Get a code-block's codewords from the codestream reader and     * parse them to find eventual embedded side-information. */    public DecLyrdCBlk getCodeBlock(int c,int m,int n,SubbandSyn sb,int fl,				    int nl,DecLyrdCBlk ccb) {	DecLyrdCBlk dlCblk = src.getCodeBlock(c,m,n,sb,fl,nl,ccb);		if(dlCblk==null) return null;	// Get codewords array	byte[] ldata = dlCblk.data;	int len = dlCblk.dl;	// Search for a terminating marker and display found information if any	int ff = 0xFF;	int n0 = 0x90;	boolean found = false;	int markLen = 0;	int markOff = 0;	for(int i=0; i<len-1; i++) {	    if((ff&ldata[i])==ff) {		if((ff&ldata[i+1])>=n0) {		    if(ldata[i+1]==(byte)0x94) { // Secure termination			markOff = i;			i+=2;			// Marker length			markLen = ((ldata[i]<<8)&0xFF00) + (ldata[i+1]&0xFF);			i += 2;			// Method type			if((ldata[i]&0xF)==0x1) {			    dlCblk.scramblingType = 				ScramblingTypes.WAV_DOMAIN_SCRAMBLING;			} else if((ldata[i]&0xF)==0x2){			    dlCblk.scramblingType = 				ScramblingTypes.COMP_DOMAIN_SCRAMBLING;			} else {			    dlCblk.scrambled = false;			    dlCblk.scramblingType = 				ScramblingTypes.NO_SCRAMBLING;			    continue;			}			// Encryption method			if((ldata[i]&0xF0)==0x0) {			    isEncrypted = false;			} else {			    isEncrypted = true;			}			i += 1;			// PPsee			if(dlCblk.scramblingType==					ScramblingTypes.					COMP_DOMAIN_SCRAMBLING) {			    dlCblk.scrambOff = ((ldata[i]<<8)&0xFF00) + 				(ldata[i+1]&0xFF);			    i += 2;			}			// Seed			if(isEncrypted) {			    byte[] val = new byte[markLen-i+markOff];			    int p = 0;			    for(; i<markLen+markOff; i++,p++) {				val[p] = ldata[i];			    }			    BigInteger eSeed = new BigInteger(val);			    BigInteger unSeed = RSAAlgorithm.rsa(eSeed,								 rsaMod,								 rsaExp);			    dlCblk.seed = unSeed.longValue();			} else {			    dlCblk.seed = ((ldata[i]<<32)&0xFF00) + 				((ldata[i+1]<<16)&0xFF00) +  				((ldata[i+2]<<8)&0xFF00) +				(ldata[i+3]&0xFF);			    i += 4;			}			dlCblk.scrambled = true;			numProtectCblk++;			found = true;			break;		    } else {			dlCblk.scrambled = false;			dlCblk.scramblingType = ScramblingTypes.NO_SCRAMBLING;		    }		}	    }	}	// No secure termination found. Code-block is not protected	if(!found) {	    dlCblk.scrambled = false;	    dlCblk.scramblingType = ScramblingTypes.NO_SCRAMBLING;	}	// Unscramble layers if needed and authorized user	if(dlCblk.scrambled && (dlCblk.scramblingType ==				ScramblingTypes.COMP_DOMAIN_SCRAMBLING)) {	    Random rd = new Random(dlCblk.seed);	    // Bit reader from byte buffer	    ByteInputBuffer bib = 		new ByteInputBuffer(dlCblk.data,dlCblk.scrambOff,				    markOff-dlCblk.scrambOff);	    ByteToBitInput bbi = new ByteToBitInput(bib);	    // Copy input to output	    int tmpIn, tmpOut, tmp;	    byte[] out = new byte[markOff-dlCblk.scrambOff];// 	    System.out.println(" -> length="+out.length);	    for(int i=dlCblk.scrambOff; i<markOff; i++) {		tmpOut = 0;		for(int j=7; j>=0; j--) {		    tmpIn = bbi.readBit();		    if(rd.nextBoolean()) {			tmpOut |= (1-tmpIn)<<j;		    } else {			tmpOut |= tmpIn<<j;		    }		}		out[i-dlCblk.scrambOff] = (byte)(0xff&tmpOut);	    }	    	    // Recopy buffer	    for(int i=dlCblk.scrambOff; i<markOff; i++) {		dlCblk.data[i] = out[i-dlCblk.scrambOff];	    }	}		return dlCblk;    }    public SubbandSyn getSynSubbandTree(int t,int c) {	return src.getSynSubbandTree(t,c);    }    public int getCbULX() {	return src.getCbULX();    }    public int getCbULY() {	return src.getCbULY();    }}