实验一

常用密码学原语的C++代码使用

1. Crypto++部署与测试

Crypto++部署

本文采用Windows子系统wsl2进行部署测试

  • 从官网下载Crypto++ (https://www.cryptopp.com/)
  • make -j4
  • make install PREFIX=./path 使用path指定安装路径
  • g++ hw1.cpp -I /usr/local/bin/include/cryptopp -o hw1.exe /usr/local/bin/lib/libcryptopp.a 使用g++进行编译

Crypto++测试

  • 使用SHA384进行测试
  • 这里利用StringSource的方法进行函数调用
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// 使用SHA384进行加密
void encryptSHA384(string& plain){
    std::string cipher, encoded;
    SHA384 hash;
    StringSource ss1(plain, true,
        new HashFilter(hash, 
            new HexEncoder( 
                new StringSink( cipher ) ) ) ); // HashFilter
    std::cout << "(SHA384) The cipher text is: " << cipher << std::endl;
}

int main(int argc, char* argv[]){
    // 测试代码
    string in_string = "Hello World";
    CryptoPP::byte key[AES::DEFAULT_KEYLENGTH] = "abcd1234";

    cout << "Original text is: " << in_string << endl;
    cout << "Key is: " << key << endl;
    // 使用SHA384进行加密
    encryptSHA384(in_string);
    ...
 }

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Crypto++使用

字符串、二进制、十六进制相互转换

  • 任务比较简单，两两转换共需要6个函数，这里我们采用环形转换的方式，即字符串转二进制、二进制转十六进制、十六进制转字符串，这样即可说明可以互相转化，我们实现3个函数即可。
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// 字符串转2进制
string string_to_bit(string& plain){
    std::string encoded = "";
    for(auto c: plain){
        bitset<8> bs(c);
        encoded += bs.to_string();
    }
    std::cout << "Binary Encoder text is: " << encoded << std::endl;
    return encoded;
}

// 2进制转16进制
string bit_to_hex(string& plain){
    std::string encoded;
    for(int i = 0; i < plain.length(); i += 8){
        stringstream ss;
        string ts;
        ss << std::hex << stoi(plain.substr(i, 8), nullptr, 2);
        ss >> ts;    
        transform(ts.begin(), ts.end(), ts.begin(), ::toupper);
        encoded += ts;
    }
    cout << "Hex Encoder text is: " << encoded << endl;
    return encoded;
}

// 16进制转字符串
string hex_to_string(string& plain){
    std::string encoded;
    StringSource ss2( plain, true,
        new HexDecoder(
            new StringSink( encoded )
        ) // HexDecoder
    ); // StringSource
    std::cout << "String text is: " << encoded << std::endl;
    return encoded;
}

int main(){
		...
    // 进制转换
    string bits,hexs,strs;
    bits = string_to_bit(in_string);
    hexs = bit_to_hex(bits);
    strs = hex_to_string(hexs);
}

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  • 通过转换我们可以发现，最后结果和初始输入相同

哈希：Sha1哈希、MD5哈希、Sha256哈希

  • 使用Crypto中的哈希类实现
  • 几类哈希方法使用方法类似，这里使用StringSource的方法，以十六进制输出
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// Sha1哈希加密
string encryptSHA1(string& plain){
    std::string cipher, encoded;
    SHA1 hash;
    StringSource ss1(plain, true,
        new HashFilter(hash, 
            new HexEncoder( 
                new StringSink( cipher ) ) ) ); // HashFilter
    std::cout << "(SHA1) The cipher text is: " << cipher << std::endl;
    return cipher;
}

// MD5哈希
string encryptMD5(string& plain){
    std::string cipher, encoded;
    MD5 hash;
    StringSource ss1(plain, true,
        new HashFilter(hash, 
            new HexEncoder( 
                new StringSink( cipher ) ) ) ); // HashFilter
    std::cout << "(MD5) The cipher text is: " << cipher << std::endl;
    return cipher;
}

// SHA256哈希
string encryptSHA256(string& plain){
    std::string cipher, encoded;
    SHA256 hash;
    StringSource ss1(plain, true,
        new HashFilter(hash, 
            new HexEncoder( 
                new StringSink( cipher ) ) ) ); // HashFilter
    std::cout << "(SHA256) The cipher text is: " << cipher << std::endl;
    return cipher;
}

int main(int argc, char* argv[]){
    ...
    // Sha1哈希
    encryptSHA1(in_string);
    // MD5哈希
    encryptMD5(in_string);
    // Sha256哈希
    encryptSHA256(in_string);
}

img

对称加密、解密：AES、DES

  • 采用ECB的模式构造AES、DES
  • 密钥为“abcd1234”，长度分别为16、8
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// AES加密
string encryptAES(string& plain, CryptoPP::byte* key){
    std::string cipher, encoded;
    ECB_Mode<AES>::Encryption e;
    e.SetKey(key, 16);
    // The StreamTransformationFilter removes
    //  padding as required.
    StringSource ss1(plain, true,
        new StreamTransformationFilter(e,
            new StringSink(cipher)) // StreamTransformationFilter
    );
    std::cout << "(AES) The cipher text is: " << cipher << std::endl;
    
    StringSource ss2( cipher, true,
        new HexEncoder(
            new StringSink( encoded )
        ) // HexDecoder
    );
    std::cout << "(AES) The hex text is: " << encoded << std::endl;
    return cipher;
}

string decryptAES(string& cipher, CryptoPP::byte* key){
    std::string recovered;
    ECB_Mode<AES>::Decryption d;
    d.SetKey(key, 16);
    // The StreamTransformationFilter removes
    //  padding as required.
    StringSource ss1(cipher, true,
        new StreamTransformationFilter(d,
            new StringSink(recovered)) // StreamTransformationFilter
    );
    std::cout << "(AES) The recovered text is: " << recovered << std::endl;
    return recovered;
}

// DES加密
string encryptDES(string& plain, CryptoPP::byte* key){
    string cipher, encoded;
    ECB_Mode<DES>::Encryption e;
    e.SetKey(key, 8);
    // The StreamTransformationFilter removes
    //  padding as required.
    StringSource ss1(plain, true,
        new StreamTransformationFilter(e,
            new StringSink(cipher)) // StreamTransformationFilter
    );
    std::cout << "(DES) The cipher text is: " << cipher << std::endl;
    
    StringSource ss2( cipher, true,
        new HexEncoder(
            new StringSink( encoded )
        ) // HexDecoder
    );
    std::cout << "(DES) The hex text is: " << encoded << std::endl;
    return cipher;
}

string decryptDES(string& cipher, CryptoPP::byte* key){
    std::string recovered;
    ECB_Mode<DES>::Decryption d;
    d.SetKey(key, 8);
    // The StreamTransformationFilter removes
    //  padding as required.
    StringSource ss1(cipher, true,
        new StreamTransformationFilter(d,
            new StringSink(recovered)) // StreamTransformationFilter
    );
    std::cout << "(DES) The recovered text is: " << recovered << std::endl;
    return recovered;
}

img

RSA非对称加密：秘钥对生成、加密、解密、签名

  • 秘钥对生成
  • key_size为2048位
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// 生成密钥
void generate_key(const unsigned int key_size, RSA::PrivateKey& private_key, RSA::PublicKey& public_key)	//钥匙的长度，通常是2048以上，越大相对越安全，但相对的运算越久
{
	AutoSeededRandomPool rng;	//伪随机数
	InvertibleRSAFunction params;
	params.GenerateRandomWithKeySize(rng, key_size);
	RSA::PrivateKey privateKey(params);
  RSA::PublicKey publicKey(params);
  private_key = privateKey;
  public_key = publicKey;
}
  • 加密
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// RSA加密
string encryptRSA(string& plain, RSA::PublicKey& public_key){
    string cipher,encoded;
    AutoSeededRandomPool rng;
    const  RSAES_OAEP_SHA_Encryptor encrypt(public_key);
    StringSource ss_1(plain, true, new 
        PK_EncryptorFilter(rng, encrypt, new  StringSink(cipher)));
    cout << "(RSA) The cipher text is: " << cipher << endl;

    StringSource ss_2(cipher, true, 
        new HexEncoder(new StringSink(encoded)));
    cout << "(RSA) The encoded text is: " << encoded << endl;
    return cipher;
}
  • 解密
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// RSA解密
string decryptRSA(string& cipher, RSA::PrivateKey& private_key){
    string recovered;
    AutoSeededRandomPool rng;
    RSAES_OAEP_SHA_Decryptor d(private_key);
    StringSource ss2(cipher, true, new 
        PK_DecryptorFilter(rng, d, new StringSink(recovered)));
    cout << "(RSA) The recovered text is: " << recovered << endl;
    return recovered;
}
  • 签名
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// RSA签名
string signatureRSA(string& plain, RSA::PrivateKey& private_key){
    string signature, encoded;
    AutoSeededRandomPool rng;
    const  RSASS<PSS, SHA256>::Signer signer(private_key);
    StringSource ss(plain, true, 
        new SignerFilter(rng, signer, new StringSink(signature)));
    cout << "(RSA) The signature is: " << signature << endl;

    StringSource ss2(signature, true,
        new HexEncoder(new StringSink(encoded)));
    cout << "(RSA) The encoded signature is: " << encoded << endl;
    return signature;
}
  • 验证
  • 验证同时需要明文和签名
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// RSA验证
string verifyRSA(string& signature, RSA::PublicKey& public_key){
    string recovered;
    const RSASS<PSS, SHA256>::Verifier verifier(public_key);
    StringSource ss(signature, true, 
        new SignatureVerificationFilter(verifier, new StringSink(recovered),
            SignatureVerificationFilter::THROW_EXCEPTION));
    cout << "(RSA) Verified signature on message" << endl;
    return recovered;
}
  • 测试代码
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int main(int argc, char* argv[]){
    ...
    // RSA
    RSA::PrivateKey private_key;
		RSA::PublicKey public_key;
    string cipher,sign,recovered,plain_cipher;
    generate_key(2048, private_key, public_key);
    cipher = encryptRSA(in_string, public_key);
    decryptRSA(cipher, private_key);
    sign = signatureRSA(in_string, private_key);
    plain_cipher = in_string + sign;
    verifyRSA(plain_cipher, public_key);
    return 0;
}

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总结

  • 利用Crypto++方法库，学习使用了主要的加解密算法
  • 代码和实验结果另附文件