从 W 参数在主机端生成 ECDSA public 密钥

Question

我想将在我的小程序中生成的私有-public 密钥对 (ECDSA) 的 public 密钥发送到主机 application/terminal。

在 RSA 中，通常我会发送模数和指数，并在主机端生成 public 密钥。

在 ECDSA 中，我从 link 中了解到，如果您将 W 参数字节取出卡外，我们也可以这样做

我现在从卡上得到了 W 个字节。有人可以建议如何从中创建 public 密钥吗？

Answer 1

我编写了这个方法来将 EC Public 密钥转换为 java.security.interfaces.ECPublicKey 密钥对象。为此，我使用了 Bouncy Castle 提供商 (bcprov-ext-jdk16-1.46.jar)。您可以从 here.

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/**
 * 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 public 密钥

Generating ECDSA public key at host side from W parameter

java

elliptic-curve

javacard

ecdsa