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package orig;
import java.math.BigInteger;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.ECFieldFp;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.ECPrivateKeySpec;
import java.security.spec.EllipticCurve;
import java.security.spec.InvalidKeySpecException;
import javax.crypto.KeyAgreement;
import java.security.spec.ECPublicKeySpec;
public class EccJava521 {
public static void main(String[] args) throws Exception {
//g the generator which is also known as the base point.
ECPoint point = new ECPoint(
// gx
new BigInteger("26617408020502170632287687167233609607298591687569" +
"73147706671368418802944996427808491545080627771902" +
"35209424122506555866215711354557091681416163731589" +
"5999846"),
// gy
new BigInteger("37571800257700204635455072244911836035944551347697" +
"62486694567779615544477440556316691234405012945539" +
"56214444453728942852258566672919658081012434427757" +
"8376784"));
final ECParameterSpec P521 = new ECParameterSpec(
new EllipticCurve(
// field the finite field that this elliptic curve is over.
new ECFieldFp(new BigInteger("68647976601306097149819007990813932172694353001433" +
"05409394463459185543183397656052122559640661454554" +
"97729631139148085803712198799971664381257402829111" +
"5057151")),
// a the first coefficient of this elliptic curve.
new BigInteger("68647976601306097149819007990813932172694353001433" +
"05409394463459185543183397656052122559640661454554" +
"97729631139148085803712198799971664381257402829111" +
"5057148"),
// b the second coefficient of this elliptic curve.
new BigInteger("10938490380737342745111123907668055699362075989516" +
"83748994586394495953116150735016013708737573759623" +
"24859213229670631330943845253159101291214232748847" +
"8985984")
),
point,
// Order n
new BigInteger("68647976601306097149819007990813932172694353001433" +
"05409394463459185543183397655394245057746333217197" +
"53296399637136332111386476861244038034037280889270" +
"7005449"),
1);
ECParameterSpec ecParameterSpec = P521;
KeyFactory keyFactory = KeyFactory.getInstance("EC");
ECPublicKeySpec pubKeySpec = new ECPublicKeySpec(point, ecParameterSpec);
PublicKey publicKey = keyFactory.generatePublic(pubKeySpec);
getAgreedKey(new BigInteger("6864797660130609714981900799081393217269435300143305409394463459185543183397655394245057746333217197532963996371363321113864768612440380340372808892707005431"),keyFactory, publicKey, ecParameterSpec);
}
private static byte[] getAgreedKey(BigInteger counter, KeyFactory keyFactory, PublicKey publicKey, ECParameterSpec ecParameterSpec) throws NoSuchAlgorithmException, InvalidKeyException, InvalidKeySpecException {
ECPrivateKeySpec privateKeySpec = new ECPrivateKeySpec(counter, ecParameterSpec);
PrivateKey recoveredPrivateKey = keyFactory.generatePrivate(privateKeySpec);
KeyAgreement keyAgreement = KeyAgreement.getInstance("ECDH");
keyAgreement.init(recoveredPrivateKey);
keyAgreement.doPhase(publicKey, true);
return keyAgreement.generateSecret();
}
}
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