如何在JavaCard中使用现有密钥对初始化EC密钥对？

Question

如何在JavaCard中使用现有密钥对初始化EC密钥对？

3

我已经拥有一个EC密钥对(secp256r1)，以二进制格式存储在字节数组中，就像这样:

// private key, 32 bytes
byte[] privKey = {0x4c, (byte)0xc7, (byte)0xcf, 0x68, (byte)0x91, 0x18, (byte)0x96, (byte)0xc8, (byte)0xe2, (byte)0xf9, (byte)0xc8, (byte)0xcc, 0x2f, 0x7f, 0x0a, (byte)0xa2, 0x1c, 0x6a, (byte)0xcb, (byte)0xba, 0x38, 0x1c, 0x10, (byte)0x9a, (byte)0xfe, (byte)0x91, 0x18, (byte)0xf6, (byte)0xca, (byte)0xd9, 0x0f, 0x0b};
//public key, 65 bytes, which is contained in a X.509 certificate
byte[] pubKey = {0x04, 0x72, (byte)0x9a, 0x71, (byte)0xd0, (byte)0x81, 0x62, 0x42, (byte)0x84, (byte)0x92, (byte)0xf2, (byte)0xd9, 0x61, (byte)0x92, 0x4d, 0x37, 0x44, 0x3a, 0x4f, 0x1b, (byte)0xda, 0x58, 0x0f, (byte)0x8a, (byte)0xea, 0x29, 0x20, (byte)0xd2, (byte)0x99, 0x7c, (byte)0xbe, (byte)0xa4, 0x39, 0x60, (byte)0xce, 0x72, (byte)0x9e, 0x35, (byte)0xc1, (byte)0xf7, 0x40, (byte)0x92, (byte)0xf2, 0x25, 0x0e, 0x60, 0x74, (byte)0x82, 0x3f, (byte)0xc5, 0x7f, 0x33, 0x60, (byte)0xb7, (byte)0xcd, 0x39, 0x69, (byte)0xc3, (byte)0xc3, 0x12, 0x5e, (byte)0xce, 0x26, 0x5c, 0x29};

这个 EC 密钥对是由 OpenSSL 生成的。我想将该 EC 密钥对存储在我的 javacard 应用程序中，这样每次使用此 EC 私钥签名消息时，都可以使用它。

但我在 javacard 3 中没有找到任何适当的 API 来设置 EC 密钥对。

我使用了这个项目 https://github.com/Yubico/ykneo-curves/blob/master/applet/src/com/yubico/ykneo/curves/SecP256r1.java 来设置 secp256r1 中的参数。

更新：我已经在 ECPublicKey 的 setW 和 ECPrivateKey 的 setS 中设置了参数，并根据 https://github.com/Yubico/ykneo-curves/blob/master/applet/src/com/yubico/ykneo/curves/SecP256r1.java 设置了其他参数。就像这样：

    privKey.setFieldFP(p, (short) 0, (short) p.length);
    privKey.setA(a, (short) 0, (short) a.length);
    privKey.setB(b, (short) 0, (short) b.length);
    privKey.setG(G, (short) 0, (short) G.length);
    privKey.setR(r, (short) 0, (short) r.length);

    byte[] privData = {(byte)0x25, (byte)0xc9, (byte)0xec, (byte)0xdc, (byte)0x4c, (byte)0x59, (byte)0xa3, (byte)0xe0, (byte)0x4f, (byte)0x01, (byte)0x56, (byte)0x97, (byte)0xf3, (byte)0xcb, (byte)0x60, (byte)0x5b, (byte)0x84, (byte)0x49, (byte)0x45, (byte)0x3a, (byte)0xe2, (byte)0x0e, (byte)0xd1, (byte)0xbd, (byte)0xc0, (byte)0xa7, (byte)0xe1, (byte)0xfa, (byte)0x82, (byte)0xee, (byte)0x3c, (byte)0x73};
    privKey.setS(privData, (short) 0, (short) privData.length);

    pubKey.setFieldFP(p, (short) 0, (short) p.length);
    pubKey.setA(a, (short) 0, (short) a.length);
    pubKey.setB(b, (short) 0, (short) b.length);
    pubKey.setG(G, (short) 0, (short) G.length);
    pubKey.setR(r, (short) 0, (short) r.length);

    byte[] pubData = {0x04, 0x00, (byte)0xb9, (byte)0x8f, (byte)0xcf, (byte)0xc3, (byte)0xc0, (byte)0xae, (byte)0x95, 0x6a, 0x5b, 0x12, 0x6d, (byte)0xbe, 0x43, (byte)0xe4, 0x7f, 0x09, 0x0d, (byte)0xde, 0x02, (byte)0xd2, 0x6b, 0x28, (byte)0x86, (byte)0xed, 0x2b, (byte)0xd7, (byte)0xe2, (byte)0xc2, 0x69, (byte)0xc1, (byte)0x89, (byte)0xb2, 0x53, (byte)0x96, (byte)0xc1, 0x2d, (byte)0xbf, 0x4c, 0x30, (byte)0xae, (byte)0xd5, (byte)0xd5, 0x3c, (byte)0xb5, (byte)0xf9, 0x3b, 0x20, 0x37, (byte)0x83, (byte)0x88, (byte)0x9f, 0x34, 0x74, (byte)0xf5, 0x6c, (byte)0x97, 0x1e, 0x0a, (byte)0xa9, (byte)0xe7, (byte)0xfa, (byte)0xa6, 0x69};
    pubKey.setW(pubData, (short) 0, (short)pubData.length);

现在我要签名这条消息：

    // the class Secp256r1 can be found in above link
    pair = SecP256r1.newKeyPair();

    ECPublicKey pubKey = (ECPublicKey) pair.getPublic();
    ECPrivateKey privKey = (ECPrivateKey) pair.getPrivate();


    byte[] data = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f};


    signature = Signature.getInstance(Signature.ALG_ECDSA_SHA, false);
    signature.init(pair.getPrivate(), Signature.MODE_SIGN);

    byte[] signData = new byte[127];
    short sendLen = signature.sign(data, (short) 0, (short) data.length, buffer, (short) 0);
    apdu.setOutgoingAndSend((short) 0, sendLen);

我发送了几个APDU来调用这段代码片段，但每次都收到不同的签名消息。为什么会出现这种情况？

- Yang Zhou

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- vojta · Accepted Answer

在ECPublicKey上有方法setW(...)，在ECPrivateKey上有方法setS(...)。

棘手的部分是你的keyPair.getPublic()和keyPair.getPrivate()返回通用接口，你需要对它们进行转换:

KeyPair keyPair = new KeyPair(KeyPair.ALG_EC_FP, KeyBuilder.LENGTH_EC_FP_256);
ECPublicKey pub = (ECPublicKey) keyPair.getPublic();
ECPrivateKey priv = (ECPrivateKey) keyPair.getPrivate();
pub.setW(pubBytes, (short) 0, (short) pubBytes.length);
priv.setS(privBytes, (short) 0, (short) privBytes.length);
//do not forget to set parameters of your curve to both private and public key HERE!!!

https://docs.oracle.com/javacard/3.0.5/api/javacard/security/ECPublicKey.html

void setW(byte[] buffer, short offset, short length) throws CryptoException

设置公钥所包含的曲线的点。该点应按照ANSI X9.62规范指定为八进制字符串。具体实现不必支持压缩格式，但必须支持未压缩的点形式。纯文本数据格式是大端对齐且右对齐（最低有效位是最后一个字节的最低有效位）。输入参数数据将被复制到内部表示中。

https://docs.oracle.com/javacard/3.0.5/api/javacard/security/ECPrivateKey.html

void setS(byte[] buffer, short offset, short length) throws CryptoException

设置密钥的值。纯文本数据格式是大端对齐且右对齐（最低有效位是最后一个字节的最低有效位）。输入参数数据将被复制到内部表示中。

答案更新：

基于椭圆曲线的签名包含一个随机数，这就是为什么每次计算签名时都会得到不同的结果。这是一种特点而非错误。