diff options
Diffstat (limited to 'src/cz/crcs/ectester/common/ec/EC_Params.java')
| -rw-r--r-- | src/cz/crcs/ectester/common/ec/EC_Params.java | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/src/cz/crcs/ectester/common/ec/EC_Params.java b/src/cz/crcs/ectester/common/ec/EC_Params.java new file mode 100644 index 0000000..1c066e7 --- /dev/null +++ b/src/cz/crcs/ectester/common/ec/EC_Params.java @@ -0,0 +1,194 @@ +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()]); + } +} |