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package cz.crcs.ectester.common.ec;
import cz.crcs.ectester.applet.EC_Consts;
import cz.crcs.ectester.common.util.ByteUtil;
import java.io.ByteArrayOutputStream;
import java.util.ArrayList;
import java.util.List;
/**
* A list of EC parameters, can contain a subset of the Fp/F2M, A, B, G, R, K, W, S parameters.
*
* The set of parameters is uniquely identified by a short bit string.
* The parameters can be exported to a byte array via <code>flatten()</code> or to a comma delimited
* string via <code>expand()</code>.
* @author Jan Jancar johny@neuromancer.sk
*/
public class EC_Params extends EC_Data {
private short params;
public EC_Params(short params) {
this.params = params;
this.count = numParams();
this.data = new byte[this.count][];
}
public EC_Params(short params, byte[][] data) {
this.params = params;
this.count = data.length;
this.data = data;
}
public EC_Params(String id, short params) {
this(params);
this.id = id;
}
public EC_Params(String id, short params, byte[][] data) {
this(params, data);
this.id = id;
}
public short getParams() {
return params;
}
public byte[][] getParam(short param) {
if (!hasParam(param)) {
return null;
}
if (Integer.bitCount(param) != 1) {
return null;
}
short paramMask = EC_Consts.PARAMETER_FP;
byte[][] result = null;
int i = 0;
while (paramMask <= EC_Consts.PARAMETER_S) {
short masked = (short) (this.params & param & paramMask);
short shallow = (short) (this.params & paramMask);
if (masked != 0) {
if (masked == EC_Consts.PARAMETER_F2M) {
result = new byte[4][];
result[0] = data[i].clone();
result[1] = data[i+1].clone();
result[2] = data[i+2].clone();
result[3] = data[i+3].clone();
break;
}
if (masked == EC_Consts.PARAMETER_G || masked == EC_Consts.PARAMETER_W) {
result = new byte[2][];
result[0] = data[i].clone();
result[1] = data[i+1].clone();
break;
}
result = new byte[1][];
result[0] = data[i].clone();
}
if (shallow == EC_Consts.PARAMETER_F2M) {
i += 4;
} else if (shallow == EC_Consts.PARAMETER_G || shallow == EC_Consts.PARAMETER_W) {
i += 2;
} else if (shallow != 0) {
i++;
}
paramMask = (short) (paramMask << 1);
}
return result;
}
public boolean hasParam(short param) {
return (params & param) != 0;
}
public int numParams() {
short paramMask = EC_Consts.PARAMETER_FP;
int num = 0;
while (paramMask <= EC_Consts.PARAMETER_S) {
if ((paramMask & params) != 0) {
if (paramMask == EC_Consts.PARAMETER_F2M) {
num += 3;
}
if (paramMask == EC_Consts.PARAMETER_W || paramMask == EC_Consts.PARAMETER_G) {
num += 1;
}
++num;
}
paramMask = (short) (paramMask << 1);
}
return num;
}
@Override
public byte[] flatten() {
return flatten(params);
}
public byte[] flatten(short params) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
short paramMask = EC_Consts.PARAMETER_FP;
int i = 0;
while (paramMask <= EC_Consts.PARAMETER_S) {
short masked = (short) (this.params & params & paramMask);
short shallow = (short) (this.params & paramMask);
if (masked != 0) {
byte[] param = data[i];
if (masked == EC_Consts.PARAMETER_F2M) {
//add m, e_1, e_2, e_3
param = ByteUtil.concatenate(param, data[i + 1]);
if (!ByteUtil.allValue(data[i + 2], (byte) 0)) {
param = ByteUtil.concatenate(param, data[i + 2]);
}
if (!ByteUtil.allValue(data[i + 3], (byte) 0)) {
param = ByteUtil.concatenate(param, data[i + 3]);
}
if (!(param.length == 4 || param.length == 8))
throw new RuntimeException("PARAMETER_F2M length is not 8.(should be)");
}
if (masked == EC_Consts.PARAMETER_G || masked == EC_Consts.PARAMETER_W) {
//read another param (the y coord) and put into X962 format.
byte[] y = data[i + 1];
param = ByteUtil.concatenate(new byte[]{4}, param, y); //<- ugly but works!
}
if (param.length == 0)
throw new RuntimeException("Empty parameter read?");
//write length
byte[] length = new byte[2];
ByteUtil.setShort(length, 0, (short) param.length);
out.write(length, 0, 2);
//write data
out.write(param, 0, param.length);
}
if (shallow == EC_Consts.PARAMETER_F2M) {
i += 4;
} else if (shallow == EC_Consts.PARAMETER_G || shallow == EC_Consts.PARAMETER_W) {
i += 2;
} else if (shallow != 0) {
i++;
}
paramMask = (short) (paramMask << 1);
}
return (out.size() == 0) ? null : out.toByteArray();
}
@Override
public String[] expand() {
List<String> out = new ArrayList<>();
short paramMask = EC_Consts.PARAMETER_FP;
int index = 0;
while (paramMask <= EC_Consts.PARAMETER_S) {
short masked = (short) (params & paramMask);
if (masked != 0) {
byte[] param = data[index];
if (masked == EC_Consts.PARAMETER_F2M) {
for (int i = 0; i < 4; ++i) {
out.add(ByteUtil.bytesToHex(data[index + i], false));
}
index += 4;
} else if (masked == EC_Consts.PARAMETER_G || masked == EC_Consts.PARAMETER_W) {
out.add(ByteUtil.bytesToHex(param, false));
out.add(ByteUtil.bytesToHex(data[index + 1], false));
index += 2;
} else {
out.add(ByteUtil.bytesToHex(param, false));
index++;
}
}
paramMask = (short) (paramMask << 1);
}
return out.toArray(new String[out.size()]);
}
}
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