从JavaCard恢复ECPublicKey到Java [英] Recovering an ECPublicKey from JavaCard to Java

问题描述

我正在尝试在终端（由计算机模拟）和智能卡（Java卡）之间实现ECDH。

I am trying to implement ECDH between a terminal (simulated by my computer) and a smart card (Java Card).

我固定了想要的椭圆曲线使用，在卡侧，我有以下代码可以运行协议的第一部分：

I fixed the elliptic curve that I want to use, and on the card side I have the following code to run the first part of the protocol :

        ECPublicKey pubKey = (ECPublicKey) KeyBuilder.buildKey(
            KeyBuilder.TYPE_EC_FP_PUBLIC, (short) 0x0100, false);
        pubKey.setFieldFP(p, (short) 0x0001, (short) 0x0020);
        pubKey.setA(a, (short) 0x0001, (short) 0x0020);
        pubKey.setB(b, (short) 0x0000, (short) 0x0020);
        pubKey.setR(r, (short) 0x0001, (short) 0x0020);
        pubKey.setG(g, (short) 0x0000, (short) g.length);

        ECPrivateKey privKey = (ECPrivateKey) KeyBuilder.buildKey(
            KeyBuilder.TYPE_EC_FP_PRIVATE, (short) 0x0100, false);

        KeyPair keypair = new KeyPair(pubKey, privKey);
        keypair.genKeyPair();

        pubKey.getW(apduBuffer, (short) 0x0000);
        setOutgoingAndSend((short) 0x0000, (short) 0x0041);

所以我为ECDH创建了一个密钥对，然后将公共密钥对发送到我的终端。

So I create a KeyPair for ECDH and I send the public one to my terminal.

我的问题如下：考虑到我得到的响应APDU，我无法重构ECPublicKey ...

My problem is the following : I am not able to reconstruct an ECPublicKey given the response APDU I get...

I没有找到任何用Java进行此操作的方法（甚至使用外部库作为Bouncy Castle）。

I did not find any way to do this in Java (even using external library as Bouncy Castle).

有人可以帮我吗？

推荐答案

JavaCard返回的公共密钥的格式如下： 04 xy 。在终端端，首先必须提取x和y坐标。然后，

The public key returned in JavaCard is formatted as follows: 04 x y. In the terminal side, first you must extract x and y coordinates. Then,

KeyFactory kf = KeyFactory.getInstance（ ECDSA， BC）;

KeyFactory kf = KeyFactory.getInstance("ECDSA", "BC");

ECPoint point = new ECPoint（x，y）;

ECPoint point = new ECPoint(x, y);

ECParameterSpec域参数= new ECParameterSpec（...）; //初始化域参数

ECParameterSpec domainparameters = new ECParameterSpec(...); // initialize your domain parameters

ECPublicKeySpec spec = new ECPublicKeySpec（point，domainparameters）;

ECPublicKeySpec spec = new ECPublicKeySpec(point, domainparameters);

ECPublicKey publickey =（ECPublicKey）kf.generatePublic（spec ）;

ECPublicKey publickey = (ECPublicKey)kf.generatePublic(spec);

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