3

我正在努力从公钥的字符串表示中创建 ECDSA 公钥，即

string     devicePublicKey("86FB5EB3CA0507226BE7197058B9EC041D3A3758D9D9C91902ACA3391F4E58AEF13AFF63CC4EF68942B9B94904DC1B890EDBEABD16B992110624968E894E560E");

以前我发现我必须在这个键前面加上'04'所以不确定这次是否需要？

我正在尝试生成它以用于验证签名

string ecs04b2ExpSignature("0199E984CEC75DDCA7F1DDF6E53E2E67352A2BE38A4B66F8ED596606FAB983FF300CAA76DE88CED9D563A5C03E8F3A7C000780F3F2061C611E9AA0B18B460D77");

要签名的数据在哪里

string      ecs04b2SigningData("020000000000000001FFFFFFFFFFFFFFFE123456789ABCDEF000B3DA2000000100000300000003030003000300");

我现在的粗略代码看起来像这样

SecByteBlock message(convertHexStrToSecByteBlock(messageIn));
SecByteBlock signature(convertHexStrToSecByteBlock(signatureIn));

ECDSA<ECP, SHA256>::PublicKey publicKey;
string inPublicKey("04");
inPublicKey.append(pubKeyIn);
SecByteBlock pubKey = encryptBase::convertHexStrToSecByteBlock(inPublicKey);



ECP::Point p;
publicKey.AccessGroupParameters().Initialize(CryptoPP::ASN1::secp256r1());
publicKey.GetGroupParameters().GetCurve().DecodePoint(p, pubKey, publicKey.GetGroupParameters().GetCurve().EncodedPointSize(true));
publicKey.SetPublicElement(p);

//ByteQueue qt;
//qt.Put((byte*)exp.c_str(),(size_t)exp.size());
AutoSeededRandomPool prng;
bool result = publicKey.Validate(prng, 3);
if (result) 
{  
    // Load public key (in ByteQueue, X509 format)
    ECDSA<ECP, SHA256>::Verifier verifier(publicKey);

    bool result = verifier.VerifyMessage(message.data(), messageIn.size(), signature.data(), signature.size());
    if (result)
        cout << "Verified signature on message" << endl;
    else
        cerr << "Failed to verify signature on message" << endl;
}
else
{
    cout << "Failed to validate key" << endl;
}

这是一起切碎的，所以不会建造。任何帮助都会很棒

PS 我在这里问了一个与私钥相关的类似问题Creation of ECDSA private key given curve and private exponent?

4

2 回答 2

3

答案在ECDSA wiki 页面上有详细说明，但并不明显。您需要执行以下操作来初始化publicKey给定的曲线和公共点：

string pt = "2DB45A3F21889438B42C8F464C75292BACF5FDDB5DA0B492501B299CBFE92D8F"
            "DB90FC8FF4026129838B1BCAD1402CAE47FE7D8084E409A41AFCE16D63579C5F";

HexDecoder decoder;
decoder.Put((byte*)pt.data(), pt.size());
decoder.MessageEnd();

ECP::Point q;
size_t len = decoder.MaxRetrievable();
// len should be GetField().MaxElementByteLength()

q.identity = false;
q.x.Decode(decoder, len/2);
q.y.Decode(decoder, len/2);

ECDSA<ECP, SHA256>::PublicKey publicKey;
publicKey.Initialize(ASN1::secp256r1(), q);

bool result = publicKey.Validate( prng, 3 );
if( result )
{
    cout << "Validated public key" << endl;
}
else
{
    cerr << "Failed to validate public key" << endl;
    exit(1);
}

const ECP::Point& qq = publicKey.GetPublicElement();
cout << "Q.x: " << std::hex << qq.x << endl;
cout << "Q.y: " << std::hex << qq.y << endl;

上面的程序产生以下结果。

$ ./cryptopp-test.exe
Validated public key
Q.x: 2db45a3f21889438b42c8f464c75292bacf5fddb5da0b492501b299cbfe92d8fh
Q.y: db90fc8ff4026129838b1bcad1402cae47fe7d8084e409a41afce16d63579c5fh

您不能使用GetField().MaxElementByteLength()，因为唯一可用的是x和y坐标。DL_GroupParameters_EC< EC >在您初始化公钥中的底层之前，诸如字段大小之类的东西将不可用。

例如，以下导致分段错误：

ECDSA<ECP, SHA256>::PublicKey publicKey;
unsigned int u = publicKey.GetGroupParameters().GetCurve().GetField().MaxElementByteLength();
cout << "Field element length: " << u << endl;

您可以篡改公钥以确保验证失败：

q.y.Decode(decoder, len/2);
q.y++;
于 2014-12-07T03:23:07.713 回答
0

这是您关于如何使用的第二个问题的答案VerifyMessage：

...
publicKey.Initialize(ASN1::secp256r1(), q);

string msg = "020000000000000001FFFFFFFFFFFFFFFE123456789ABCDEF000B3DA2000000100000300000003030003000300";
string sig = "0199E984CEC75DDCA7F1DDF6E53E2E67352A2BE38A4B66F8ED596606FAB983FF300CAA76DE88CED9D563A5C03E8F3A7C000780F3F2061C611E9AA0B18B460D77";

string mm, ss;

decoder.Detach(new StringSink(mm));
decoder.Put((byte*)msg.data(), msg.size());
decoder.MessageEnd();

decoder.Detach(new StringSink(ss));
decoder.Put((byte*)sig.data(), sig.size());
decoder.MessageEnd();

ECDSA<ECP, SHA256>::Verifier verifier(publicKey);
result = verifier.VerifyMessage((byte*)mm.data(), mm.size(), (byte*)ss.data(), ss.size());

if( result )
{
    cout << "Verified message" << endl;
}
else
{ 
    cerr << "Failed to verify message" << endl;
    exit(1);
}

调用删除当前过滤器，并用新过滤器替换它Detach。HexDecoder在上面的代码中，它的StringSink. 您必须这样做以确保不会泄漏内存。

您的消息未在公钥下验证：

$ ./cryptopp-test.exe
Validated public key
Failed to verify message

您也可以尝试验证 ASCII 消息而不是二进制消息，但它也无法验证：

decoder.Attach(new StringSink(mm));
decoder.Put((byte*)msg.data(), msg.size());
decoder.MessageEnd();

// Swap in the ASCII message for the binary message
mm = msg;

所以有人给了你错误的信息、错误的签名或错误的公钥（或某种组合）。

于 2014-12-07T05:37:01.837 回答