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我第一次使用 Crypto++，遇到了一些麻烦。为什么这在 C# 中有效（使用相同的密钥），但在 Crypto++ 中无效？我将在下面展示我的 C# 和 C++ 代码。

C# 代码（这有效！）：

byte[] Modulus = new byte[] { 0xA3, 0x1D, 0x6C, 0xE5, 0xFA, 0x95, 0xFD, 0xE8, 0x90, 0x21, 0xFA, 0xD1, 0x0C, 0x64, 0x19, 0x2B, 0x86, 0x58, 0x9B, 0x17, 0x2B, 0x10, 0x05, 0xB8, 0xD1, 0xF8, 0x4C, 0xEF, 0x53, 0x4C, 0xD5, 0x4E, 0x5C, 0xAE, 0x86, 0xEF, 0x92, 0x7B, 0x90, 0xD1, 0xE0, 0x62, 0xFD, 0x7C, 0x54, 0x55, 0x9E, 0xE0, 0xE7, 0xBE, 0xFA, 0x3F, 0x9E, 0x15, 0x6F, 0x6C, 0x38, 0x4E, 0xAF, 0x07, 0x0C, 0x61, 0xAB, 0x51, 0x5E, 0x23, 0x53, 0x14, 0x18, 0x88, 0xCB, 0x6F, 0xCB, 0xC5, 0xD6, 0x30, 0xF4, 0x06, 0xED, 0x24, 0x23, 0xEF, 0x25, 0x6D, 0x00, 0x91, 0x77, 0x24, 0x9B, 0xE5, 0xA3, 0xC0, 0x27, 0x90, 0xC2, 0x97, 0xF7, 0x74, 0x9D, 0x6F, 0x17, 0x83, 0x7E, 0xB5, 0x37, 0xDE, 0x51, 0xE8, 0xD7, 0x1C, 0xE1, 0x56, 0xD9, 0x56, 0xC8, 0xC3, 0xC3, 0x20, 0x9D, 0x64, 0xC3, 0x2F, 0x8C, 0x91, 0x92, 0x30, 0x6F, 0xDB };
byte[] Exponent = new byte[] { 0x00, 0x01, 0x00, 0x01 };
byte[] P = new byte[] { 0xCC, 0xE7, 0x5D, 0xFE, 0x72, 0xB6, 0xFD, 0xE7, 0x1D, 0xE3, 0x1A, 0x0E, 0xAC, 0x33, 0x7A, 0xB9, 0x21, 0xE8, 0x8A, 0x84, 0x9B, 0xDA, 0x9F, 0x1E, 0x58, 0x34, 0x68, 0x7A, 0xB1, 0x1D, 0x7E, 0x1C, 0x18, 0x52, 0x65, 0x7B, 0x97, 0x8E, 0xA7, 0x6A, 0x9D, 0xEE, 0x5A, 0x77, 0x52, 0x3B, 0x71, 0x8F, 0x33, 0xD0, 0x49, 0x5E, 0xC3, 0x30, 0x39, 0x72, 0x36, 0xBF, 0x1D, 0xD9, 0xF2, 0x24, 0xE8, 0x71 };
byte[] Q = new byte[] { 0xCB, 0xCA, 0x58, 0x74, 0xD4, 0x03, 0x62, 0x93, 0x06, 0x50, 0x1F, 0x42, 0xF6, 0xAA, 0x59, 0x36, 0xA7, 0xA1, 0xF3, 0x97, 0x5C, 0x9A, 0xC8, 0x6A, 0x27, 0xCF, 0x85, 0x05, 0x2A, 0x66, 0x41, 0x6A, 0x7F, 0x2F, 0x84, 0xC8, 0x18, 0x13, 0xC6, 0x1D, 0x8D, 0xC7, 0x32, 0x2F, 0x72, 0x19, 0x3F, 0xA4, 0xED, 0x71, 0xE7, 0x61, 0xC0, 0xCF, 0x61, 0xAE, 0x8B, 0xA0, 0x68, 0xA7, 0x7D, 0x83, 0x23, 0x0B };
byte[] DP = new byte[] { 0x4C, 0xCA, 0x74, 0xE6, 0x74, 0x35, 0x72, 0x48, 0x58, 0x62, 0x11, 0x14, 0xE8, 0xA2, 0x4E, 0x5E, 0xED, 0x7F, 0x49, 0xD2, 0x52, 0xDA, 0x87, 0x01, 0x87, 0x4A, 0xF4, 0xD0, 0xEE, 0x69, 0xC0, 0x26, 0x65, 0x53, 0x13, 0xE7, 0x52, 0xB0, 0x4A, 0xBB, 0xE1, 0x3E, 0x3F, 0xB7, 0x32, 0x21, 0x46, 0xF8, 0xC5, 0x11, 0x4D, 0x3D, 0xEF, 0x66, 0xB6, 0x50, 0xC0, 0x85, 0xB5, 0x79, 0x45, 0x8F, 0x61, 0x71 };
byte[] InverseQ = new byte[] { 0x28, 0x6A, 0xBB, 0xD1, 0x93, 0x95, 0x94, 0x1A, 0x6E, 0xED, 0xD7, 0x0E, 0xC0, 0x61, 0x2B, 0xC2, 0xEF, 0xE1, 0x86, 0x3D, 0x34, 0x12, 0x88, 0x6F, 0x94, 0xA4, 0x48, 0x6E, 0xC9, 0x87, 0x1E, 0x46, 0x00, 0x46, 0x00, 0x52, 0x8E, 0x9F, 0x47, 0xC0, 0x8C, 0xAB, 0xBC, 0x49, 0xAC, 0x5B, 0x13, 0xF2, 0xEC, 0x27, 0x8D, 0x1B, 0x6E, 0x51, 0x06, 0xA6, 0xF1, 0x62, 0x1A, 0xEB, 0x78, 0x2E, 0x88, 0x48 };
byte[] D = new byte[] { 0x9B, 0xF9, 0xDE, 0xC2, 0x45, 0x93, 0x4C, 0x4C, 0xAC, 0x48, 0x2B, 0xA8, 0x4D, 0xFC, 0xD7, 0xED, 0xB2, 0xFB, 0x72, 0xE9, 0xEA, 0xC1, 0x88, 0x39, 0x07, 0x2A, 0x6F, 0x34, 0x07, 0x81, 0x97, 0x7E, 0xCD, 0xFA, 0x21, 0x02, 0xF5, 0xDD, 0x30, 0xDD, 0x22, 0x4A, 0xB3, 0x41, 0xE5, 0x89, 0x80, 0x73, 0xC4, 0xAF, 0x90, 0x9E, 0x2B, 0x50, 0x8A, 0x0A, 0xD4, 0x6E, 0xBD, 0x0F, 0x15, 0x79, 0x37, 0x95, 0xE8, 0x3D, 0xCF, 0x4C, 0x6D, 0xFF, 0x51, 0x65, 0xE7, 0x90, 0xC1, 0xAC, 0x2D, 0xC6, 0xEB, 0x47, 0x19, 0x2D, 0xD0, 0x58, 0x74, 0x79, 0xAC, 0x08, 0x1C, 0xA3, 0x1D, 0xD0, 0xCE, 0x39, 0x2E, 0xC3, 0xFA, 0x66, 0xEF, 0xC7, 0x8E, 0x10, 0x2F, 0xE4, 0xA1, 0xE7, 0x4E, 0xA8, 0x42, 0xF0, 0xF4, 0xFD, 0x10, 0xA6, 0x67, 0x64, 0xCB, 0x3A, 0x6D, 0x4D, 0x51, 0xEC, 0x1F, 0x9D, 0x56, 0x26, 0xC2, 0xFC };
byte[] DQ = new byte[] { 0xAF, 0xDC, 0x46, 0xE7, 0x52, 0x8A, 0x35, 0x47, 0xA1, 0x1C, 0x05, 0x4E, 0x39, 0x24, 0x99, 0xE6, 0x43, 0x54, 0xCB, 0xAB, 0xE3, 0xDB, 0x22, 0x76, 0x11, 0x32, 0xD0, 0x9C, 0xBB, 0x91, 0x10, 0x84, 0x81, 0x8B, 0x15, 0x2F, 0xC3, 0x2F, 0x55, 0x38, 0xED, 0xBF, 0x67, 0x3C, 0x70, 0x5E, 0xFF, 0x80, 0x28, 0xF3, 0xB1, 0x73, 0xB6, 0xFA, 0x7F, 0x56, 0x2B, 0xE1, 0xDA, 0x4E, 0x27, 0x4E, 0xC2, 0x2F }; 


RSAParameters rsaParams = new RSAParameters();
rsaParams.Modulus = Modulus;
rsaParams.Exponent = Exponent;
rsaParams.P = P;
rsaParams.Q = Q;
rsaParams.DP = DP;
rsaParams.InverseQ = InverseQ;
rsaParams.D = D;
rsaParams.DQ = DQ;

RSACryptoServiceProvider crypt = new RSACryptoServiceProvider();
crypt.ImportParameters(rsaParams);

RSAPKCS1SignatureFormatter formatter = new RSAPKCS1SignatureFormatter();
formatter.SetHashAlgorithm("SHA1");
formatter.SetKey(crypt);

byte[] dataFile = new byte[] { 0x6F, 0x9F, 0x07, 0x04, 0xE2, 0x1A, 0xF7, 0xB8, 0xB2, 0x4F, 0x8D, 0x66, 0x49, 0xA1, 0x09, 0xA7, 0xB2, 0x22, 0x3C, 0xF9};

byte[] signature = formatter.CreateSignature(dataFile);

现在，我的 C++ 代码不起作用：

const char ModulusCON[0x80] = { 0xA3, 0x1D, 0x6C, 0xE5, 0xFA, 0x95, 0xFD, 0xE8, 0x90, 0x21, 0xFA, 0xD1, 0x0C, 0x64, 0x19, 0x2B, 0x86, 0x58, 0x9B, 0x17, 0x2B, 0x10, 0x05, 0xB8, 0xD1, 0xF8, 0x4C, 0xEF, 0x53, 0x4C, 0xD5, 0x4E, 0x5C, 0xAE, 0x86, 0xEF, 0x92, 0x7B, 0x90, 0xD1, 0xE0, 0x62, 0xFD, 0x7C, 0x54, 0x55, 0x9E, 0xE0, 0xE7, 0xBE, 0xFA, 0x3F, 0x9E, 0x15, 0x6F, 0x6C, 0x38, 0x4E, 0xAF, 0x07, 0x0C, 0x61, 0xAB, 0x51, 0x5E, 0x23, 0x53, 0x14, 0x18, 0x88, 0xCB, 0x6F, 0xCB, 0xC5, 0xD6, 0x30, 0xF4, 0x06, 0xED, 0x24, 0x23, 0xEF, 0x25, 0x6D, 0x00, 0x91, 0x77, 0x24, 0x9B, 0xE5, 0xA3, 0xC0, 0x27, 0x90, 0xC2, 0x97, 0xF7, 0x74, 0x9D, 0x6F, 0x17, 0x83, 0x7E, 0xB5, 0x37, 0xDE, 0x51, 0xE8, 0xD7, 0x1C, 0xE1, 0x56, 0xD9, 0x56, 0xC8, 0xC3, 0xC3, 0x20, 0x9D, 0x64, 0xC3, 0x2F, 0x8C, 0x91, 0x92, 0x30, 0x6F, 0xDB }; 
const char ExponentCON[0x4] = { 0x00, 0x01, 0x00, 0x01 }; 
const char PCON[0x40] = { 0xCC, 0xE7, 0x5D, 0xFE, 0x72, 0xB6, 0xFD, 0xE7, 0x1D, 0xE3, 0x1A, 0x0E, 0xAC, 0x33, 0x7A, 0xB9, 0x21, 0xE8, 0x8A, 0x84, 0x9B, 0xDA, 0x9F, 0x1E, 0x58, 0x34, 0x68, 0x7A, 0xB1, 0x1D, 0x7E, 0x1C, 0x18, 0x52, 0x65, 0x7B, 0x97, 0x8E, 0xA7, 0x6A, 0x9D, 0xEE, 0x5A, 0x77, 0x52, 0x3B, 0x71, 0x8F, 0x33, 0xD0, 0x49, 0x5E, 0xC3, 0x30, 0x39, 0x72, 0x36, 0xBF, 0x1D, 0xD9, 0xF2, 0x24, 0xE8, 0x71 }; 
const char QCON[0x40] = { 0xCB, 0xCA, 0x58, 0x74, 0xD4, 0x03, 0x62, 0x93, 0x06, 0x50, 0x1F, 0x42, 0xF6, 0xAA, 0x59, 0x36, 0xA7, 0xA1, 0xF3, 0x97, 0x5C, 0x9A, 0xC8, 0x6A, 0x27, 0xCF, 0x85, 0x05, 0x2A, 0x66, 0x41, 0x6A, 0x7F, 0x2F, 0x84, 0xC8, 0x18, 0x13, 0xC6, 0x1D, 0x8D, 0xC7, 0x32, 0x2F, 0x72, 0x19, 0x3F, 0xA4, 0xED, 0x71, 0xE7, 0x61, 0xC0, 0xCF, 0x61, 0xAE, 0x8B, 0xA0, 0x68, 0xA7, 0x7D, 0x83, 0x23, 0x0B }; 
const char DPCON[0x40] = { 0x4C, 0xCA, 0x74, 0xE6, 0x74, 0x35, 0x72, 0x48, 0x58, 0x62, 0x11, 0x14, 0xE8, 0xA2, 0x4E, 0x5E, 0xED, 0x7F, 0x49, 0xD2, 0x52, 0xDA, 0x87, 0x01, 0x87, 0x4A, 0xF4, 0xD0, 0xEE, 0x69, 0xC0, 0x26, 0x65, 0x53, 0x13, 0xE7, 0x52, 0xB0, 0x4A, 0xBB, 0xE1, 0x3E, 0x3F, 0xB7, 0x32, 0x21, 0x46, 0xF8, 0xC5, 0x11, 0x4D, 0x3D, 0xEF, 0x66, 0xB6, 0x50, 0xC0, 0x85, 0xB5, 0x79, 0x45, 0x8F, 0x61, 0x71 }; 
const char InverseQCON[0x40] = { 0x28, 0x6A, 0xBB, 0xD1, 0x93, 0x95, 0x94, 0x1A, 0x6E, 0xED, 0xD7, 0x0E, 0xC0, 0x61, 0x2B, 0xC2, 0xEF, 0xE1, 0x86, 0x3D, 0x34, 0x12, 0x88, 0x6F, 0x94, 0xA4, 0x48, 0x6E, 0xC9, 0x87, 0x1E, 0x46, 0x00, 0x46, 0x00, 0x52, 0x8E, 0x9F, 0x47, 0xC0, 0x8C, 0xAB, 0xBC, 0x49, 0xAC, 0x5B, 0x13, 0xF2, 0xEC, 0x27, 0x8D, 0x1B, 0x6E, 0x51, 0x06, 0xA6, 0xF1, 0x62, 0x1A, 0xEB, 0x78, 0x2E, 0x88, 0x48 }; 
const char DCON[0x80] = { 0x9B, 0xF9, 0xDE, 0xC2, 0x45, 0x93, 0x4C, 0x4C, 0xAC, 0x48, 0x2B, 0xA8, 0x4D, 0xFC, 0xD7, 0xED, 0xB2, 0xFB, 0x72, 0xE9, 0xEA, 0xC1, 0x88, 0x39, 0x07, 0x2A, 0x6F, 0x34, 0x07, 0x81, 0x97, 0x7E, 0xCD, 0xFA, 0x21, 0x02, 0xF5, 0xDD, 0x30, 0xDD, 0x22, 0x4A, 0xB3, 0x41, 0xE5, 0x89, 0x80, 0x73, 0xC4, 0xAF, 0x90, 0x9E, 0x2B, 0x50, 0x8A, 0x0A, 0xD4, 0x6E, 0xBD, 0x0F, 0x15, 0x79, 0x37, 0x95, 0xE8, 0x3D, 0xCF, 0x4C, 0x6D, 0xFF, 0x51, 0x65, 0xE7, 0x90, 0xC1, 0xAC, 0x2D, 0xC6, 0xEB, 0x47, 0x19, 0x2D, 0xD0, 0x58, 0x74, 0x79, 0xAC, 0x08, 0x1C, 0xA3, 0x1D, 0xD0, 0xCE, 0x39, 0x2E, 0xC3, 0xFA, 0x66, 0xEF, 0xC7, 0x8E, 0x10, 0x2F, 0xE4, 0xA1, 0xE7, 0x4E, 0xA8, 0x42, 0xF0, 0xF4, 0xFD, 0x10, 0xA6, 0x67, 0x64, 0xCB, 0x3A, 0x6D, 0x4D, 0x51, 0xEC, 0x1F, 0x9D, 0x56, 0x26, 0xC2, 0xFC }; 
const char DQCON[0x40] = { 0xAF, 0xDC, 0x46, 0xE7, 0x52, 0x8A, 0x35, 0x47, 0xA1, 0x1C, 0x05, 0x4E, 0x39, 0x24, 0x99, 0xE6, 0x43, 0x54, 0xCB, 0xAB, 0xE3, 0xDB, 0x22, 0x76, 0x11, 0x32, 0xD0, 0x9C, 0xBB, 0x91, 0x10, 0x84, 0x81, 0x8B, 0x15, 0x2F, 0xC3, 0x2F, 0x55, 0x38, 0xED, 0xBF, 0x67, 0x3C, 0x70, 0x5E, 0xFF, 0x80, 0x28, 0xF3, 0xB1, 0x73, 0xB6, 0xFA, 0x7F, 0x56, 0x2B, 0xE1, 0xDA, 0x4E, 0x27, 0x4E, 0xC2, 0x2F }; 

// set the params
CryptoPP::AutoSeededRandomPool rng;
InvertibleRSAFunction params;

Integer integ(ModulusCON);
params.SetModulus(integ);

Integer integ1(ExponentCON);
params.SetPublicExponent(integ1);

Integer integ2(PCON);
params.SetPrime1(integ2);

Integer integ3(QCON);
params.SetPrime2(integ3);

Integer integ4(DPCON);
params.SetModPrime1PrivateExponent(integ4);

Integer integ5(InverseQCON);
params.SetMultiplicativeInverseOfPrime2ModPrime1(integ5);

Integer integ6(DCON);
params.SetPrivateExponent(integ6);

Integer integ7(DQCON);
params.SetModPrime2PrivateExponent(integ7);

// create the keys
RSA::PrivateKey privateKey(params);
RSA::PublicKey publicKey(params);

CryptoPP::RSASSA_PKCS1v15_SHA_Signer signer(privateKey);

unsigned char data[20] = { 0x6F, 0x9F, 0x07, 0x04, 0xE2, 0x1A, 0xF7, 0xB8, 0xB2, 0x4F, 0x8D, 0x66, 0x49, 0xA1, 0x09, 0xA7, 0xB2, 0x22, 0x3C, 0xF9 };
BYTE *signature = new BYTE[0x80];
signer.SignMessage(rng, data, 20, signature);

根据我所知道的，Crypto++ 的 'RSASSA_PKCS1v15_SHA_Signer' 是我想要的等同于 C# 的 'RSAPKCS1SignatureFormatter' 并将散列算法设置为 SHA1。

它抛出的错误是：

proj.exe 中 0x7646B9BC 处未处理的异常：Microsoft C++ 异常：> CryptoPP::PK_SignatureScheme::KeyTooShort 在内存位置 0x0040EF18。

感谢您的帮助，Hetelek。

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2 回答 2

4

我无法回答为什么这在 C# 中有效，但至于 Crypto++，有几个问题。


首先，您可能调用了错误的构造函数Integer。我猜你想要这个从大端字节数组转换的：

Integer (const byte *encodedInteger, size_t byteCount, Signedness s=UNSIGNED)

但正在使用这个从以 2、8、10 或 16 为基数的字符串（在您的情况下为 10）转换的字符串。

因此，ExponentCON以示例为例，您应该这样做：

const int ExponentSize(0x4);
const byte ExponentCON[ExponentSize] = { 0x00, 0x01, 0x00, 0x01 };
Integer integ1(ExponentCON, ExponentSize);

或者可能更好：

std::string ExponentCON("101h");  // <-- Note trailing 'h' indicating hex encoding
Integer integ1(ExponentCON.c_str());


接下来， 的成员InvertibleRSAFunction必须满足某些条件才能成为有效密钥。这些可以通过单步执行InvertibleRSAFunction::Validate函数来查看，我假设检查此处描述的条件。

params.Validate(rng, 3);  // Returns false for your input data


有一些辅助函数旨在避免在您执行操作时显式设置所有内容。我不知道这些是否适合你，但我指的是InvertibleRSAFunction::GenerateRandomWithKeySize和重载的InvertibleRSAFunction::Initialize.

Crypto++ Wiki通过示例代码描述了这些函数的使用。

于 2012-08-11T15:51:24.607 回答
1

TLDR：您的私人指数 ,d在您的示例程序中是错误的。你还有其他更明显的问题。但d正在引起数学问题。

它引出了一个问题，它在 C# 中是如何工作的？数学不会因计算机语言和运行时而改变。

第一个问题是使用声明chars：

...
const char ExponentCON[0x4] = { 0x00, 0x01, 0x00, 0x01 }; 
...

这会导致您使用 ASCII 字符串的构造函数，这是错误的Integer构造函数。这至少会导致两个问题：

// Added for testing
if (integ != integ2 * integ3)
{
    cerr << "error: n != p*q" << endl;
}

// Added for testing
params.ThrowIfInvalid(prng, 3);

运行程序时，ThrowIfInvalid验证参数及其来源CryptoMaterial: ...：

error: n != p*q
CryptoMaterial: this object contains invalid values

const char需要更改const byte为. 然后：

Integer integ(ModulusCON, sizeof(ModulusCON));
params.SetModulus(integ);

Integer integ1(ExponentCON, sizeof(ExponentCON));
params.SetPublicExponent(integ1);

Integer integ2(PCON, sizeof(PCON));
params.SetPrime1(integ2);

Integer integ3(QCON, sizeof(QCON));
params.SetPrime2(integ3);
...

进行该更改后，上面的此错误消息将消失：error: n != p*q. 但CryptoMaterial: this object contains invalid values遗体。

第二个问题似乎是您的某些私钥参数不正确。您可以通过查看第 250 行附近InvertibleRSAFunction::Validate的源代码来了解正在执行的测试。rsa.cpp

Initialize您可以通过使用that take{n,e,d}部分避开它，并让Initializefactor 和解决：

Integer n(ModulusCON, sizeof(ModulusCON));
Integer e(ExponentCON, sizeof(ExponentCON));
Integer d(DCON, sizeof(DCON));

params.Initialize(n,e,d);
params.ThrowIfInvalid(prng, 3);

但是，这会导致：

InvertibleRSAFunction: input is not a valid RSA private key

接下来，检查p和q。#include <nbtheory.h>， 接着：

Integer p(PCON, sizeof(PCON));
Integer q(QCON, sizeof(QCON));

cout << "P is prime: " << (VerifyPrime(prng, p, 10) ? "yes" : "no") << endl;
cout << "Q is prime: " << (VerifyPrime(prng, q, 10) ? "yes" : "no") << endl;

结果是：

$ ./test.exe
P is prime: yes
Q is prime: yes

此时，问题似乎出在其中一个指数上。

接下来，假设e与phi 互质，#include <modarith.h>然后：

Integer n(ModulusCON, sizeof(ModulusCON));
Integer p(PCON, sizeof(PCON));
Integer q(QCON, sizeof(QCON));

Integer e(ExponentCON, sizeof(ExponentCON));    
Integer phi = (p-1)*(q-1);

ModularArithmetic ma(phi);
Integer d = ma.MultiplicativeInverse(e);

params.Initialize(n,e,d);
params.ThrowIfInvalid(prng, 3);

cout << "Validated parameters" << endl;

结果是：

$ ./test.exe
Validated parameters

所以，问题出在你的d指数上。打印很容易cout << std::hex << d << endl：

$ ./test.exe
Validated parameters

174bcc91cc08400b470a9357e7fd23db2384e4219af4dedc56a0afdc3e796abd965f16c680954549
b4526f01a2c9d7b727620f3ba6c848f19bd9210650ae62593249d7a4e0522ad48aea559d4f6a1f3f
6ae9953bed7c947e273d455a4982523dd90640b0a25572ae8c5e064e39807ddf778af96afd492999
acc40919a4d4f601h

如您所见，计算的第一个八位字节d是 0x17，但d您提供的第一个八位字节是 0x9B。

此外，您可能想要执行以下操作：

unsigned char data[20] = { 0x6F, 0x9F, 0x07, 0x04, 0xE2, 0x1A, 0xF7, 0xB8, 0xB2, 0x4F,
                           0x8D, 0x66, 0x49, 0xA1, 0x09, 0xA7, 0xB2, 0x22, 0x3C, 0xF9 };

const size_t req = signer.MaxSignatureLength(sizeof(data));
byte signature[req];
const size_t used = signer.SignMessage(prng, data, 20, signature);
// Trim 'signature' to 'used'
于 2016-04-08T02:02:50.213 回答