C# 基於大整數類的 RSA 算法實現 (2) — 公鑰加密與私鑰解密

公鑰加密（機密性）

/// 
透過公鑰加密
public byte[] EncryptByPublicKey(string dataStr)
{
    RSAParameters rsap = RSA.ExportParameters(false);
    BigInteger biN = new BigInteger(rsap.Modulus);
    BigInteger biE = new BigInteger(rsap.Exponent);
    return EncryptString(dataStr, biE, biN); // 以公鑰指數 e 加密
}

/// 
指定參數公鑰加密
public byte[] EncryptByPublicKey(string dataStr, string n, string e)
{
    BigInteger biN = new BigInteger(n, 16);
    BigInteger biE = new BigInteger(e, 16);
    return EncryptString(dataStr, biE, biN);
}

私鑰解密

/// 
透過私鑰解密
public string DecryptByPrivateKey(byte[] dataBytes)
{
    RSAParameters rsap = RSA.ExportParameters(true);
    BigInteger biN = new BigInteger(rsap.Modulus);
    BigInteger biD = new BigInteger(rsap.D);
    return DecryptBytes(dataBytes, biD, biN); // 以私鑰指數 d 解密
}

/// 
指定參數私鑰解密
public string DecryptByPrivateKey(byte[] dataBytes, string n, string d)
{
    BigInteger biN = new BigInteger(n, 16);
    BigInteger biD = new BigInteger(d, 16);
    return DecryptBytes(dataBytes, biD, biN);
}

雙重用途總結

核心邏輯皆委派給 EncryptString / DecryptBytes，差別在於傳入的指數參數。