将一个字节编码的Key转回到它在Bouncy Castle中的原始ECPublicKey

Question

在Java中,我有一个ECDH公钥,我将其作为字节数组发送.

收到字节数组后,如何将其重新转换为公钥？

我正在使用Bouncy Castle,但Java解决方案同样有用.

谢谢

Answer 1

当你得到编码密钥时,假设你使用了默认的"[your keyPair] .getPublic().getEncoded()"方法,这将有效.

    X509EncodedKeySpec ks = new X509EncodedKeySpec(pubKeyByteString.toByteArray());
    KeyFactory kf;
    try {
         kf = java.security.KeyFactory.getInstance("ECDH");
    } catch (NoSuchAlgorithmException e) {
        log.error("Cryptography error: could not initialize ECDH keyfactory!", e);
        return;
    }

    ECPublicKey remotePublicKey;

    try {
        remotePublicKey = (ECPublicKey)kf.generatePublic(ks);
    } catch (InvalidKeySpecException e) {
        log.warn("Received invalid key specification from client",e);
        return;
    } catch (ClassCastException e) {
        log.warn("Received valid X.509 key from client but it was not EC Public Key material",e);
        return;
    }

Answer 2

我发现@LaceCard 的上述解决方案对我不起作用。一般来说，这并不明显，但密码学中没有什么是;)

String key = "MihU9ztW9sEvkBL6BxyaOMgkSbodNS8yoHaHcio+WE...blahblah"
byte[] keyBytes = Base64.decode(key);

//If using Android and Spongycastle provider should be "SC"
KeyFactory kf = KeyFactory.getInstance("ECDH", "BC");
//CURVE_NAME e.g prime192v1
ECParameterSpec ecSpec = ECNamedCurveTable.getParameterSpec(CURVE_NAME);
ECPoint point = ecSpec.getCurve().decodePoint(keyBytes);
ECPublicKeySpec pubSpec = new ECPublicKeySpec(point, ecSpec);

ECPublicKey myECPublicKey = (ECPublicKey) kf.generatePublic(pubSpec);

注意：您需要适当地处理潜在的异常

Answer 3

ECDH 密钥的原始字节如何格式化？你从哪里获得原始字节？

通常，使用适当的 *Spec 类将原始密钥材料转换为 Key，但 ECPublicKeySpec和DHPublicKeySpec类不接受原始字节数组。