Question

我想将我的applet中生成的私钥 - 公钥对（ECDSA）的公钥发送到主机应用程序/终端。

在RSA中，我会发送模数和指数，并在主机端生成公钥。

在ECDSA中，我从链接中读取了如果你在卡片Click here: Stackoverflow Answer: encode public key on Java外面取W参数字节我们可以做同样的事情

我现在有来自卡片的W字节。有人可以建议如何从这个创建公钥吗？

Answer 1

我写了这个方法将EC公钥转换为java.security.interfaces.ECPublicKey密钥对象。为此，我使用了Bouncy Castle提供程序（bcprov-ext-jdk16-1.46.jar）。您可以从here下载最新版本。

/**
 * This method converts the EC public key (ECPublicKey#getW()) into ECPublicKey
 * @param cardPublicKey as W
 * @param curveName (for example "P-224")
 * @return java.security.interfaces.ECPublicKey
 */
public ECPublicKey ucPublicKeyToPublicKey(byte[] cardPublicKey, String curveName) {
    //for example curveName = "P-224";
    java.security.interfaces.ECPublicKey ecPublicKey = null; // java.security.interfaces.ECPublicKey
    java.security.KeyFactory kf = null;

    org.bouncycastle.jce.spec.ECNamedCurveParameterSpec ecNamedCurveParameterSpec = ECNamedCurveTable.getParameterSpec(curveName);
    org.bouncycastle.math.ec.ECCurve curve = ecNamedCurveParameterSpec.getCurve();
    java.security.spec.EllipticCurve ellipticCurve = EC5Util.convertCurve(curve, ecNamedCurveParameterSpec.getSeed());
    java.security.spec.ECPoint ecPoint = ECPointUtil.decodePoint(ellipticCurve, cardPublicKey);
    java.security.spec.ECParameterSpec ecParameterSpec = EC5Util.convertSpec(ellipticCurve, ecNamedCurveParameterSpec);
    java.security.spec.ECPublicKeySpec publicKeySpec = new java.security.spec.ECPublicKeySpec(ecPoint, ecParameterSpec);

    try {
        kf = java.security.KeyFactory.getInstance("EC", "BC");
    } catch (Exception e) {
        System.out.println("Caught Exception kf : " + e.toString());
    }

    try {
        ecPublicKey = (ECPublicKey) kf.generatePublic(publicKeySpec);
    } catch (Exception e) {
        System.out.println("Caught Exception public key: " + e.toString());
    }

    return ecPublicKey;
}

从W参数在主机端生成ECDSA公钥

1 个答案: