C# 在Dapper.NET中使用varbinary参数

我试图在Dapper.NET中使用

varbinary

参数，如下所示

string secret = "secret";

// from SELECT ENCRYPTBYPASSPHRASE('secret', N'xx') >>;
string ciphertext = "0x01000000393FE233AE939CA815AB744DDC39667860B3B630C82F36F7"; 
using (var conn = new SqlConnection(...))
{
    var result = conn.ExecuteScalar(@"SELECT CONVERT(NVARCHAR(4000), DECRYPTBYPASSPHRASE(@secret, @ciphertext)) as decrypted", 
        new
        {
            secret,
            ciphertext = Encoding.Unicode.GetBytes(ciphertext)
        });
}

但是结果是

null

。但是如果我直接运行SQL，它会返回一个有效的结果

SELECT CONVERT(NVARCHAR(40), DECRYPTBYPASSPHRASE('secret',  0x01000000393FE233AE939CA815AB744DDC39667860B3B630C82F36F7))

返回加密文本

xx

---

你知道我做错了什么吗？

为了让别人觉得有用，以下内容起了作用（感谢@Rob的评论）

而hexstring to bytes和bytes to hexstring函数是

public static byte[] StringToByteArray(string hex)
{
    int startIndex = 0;
    if (hex.StartsWith("0x", StringComparison.InvariantCultureIgnoreCase))
        startIndex = 2;

    return Enumerable.Range(startIndex, hex.Length - startIndex)
                     .Where(x => x % 2 == 0)
                     .Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
                     .ToArray();
}

public static string ByteArrayToString(byte[] arr)
{
    return "0x" + BitConverter.ToString(arr).Replace("-", String.Empty);
}

---

Encoding.Unicode.GetBytes

将获取十六进制值的字符串表示形式的字节数组，用于获取

密文的正确值
public static byte[] StringToByteArray(string hex)
{
    int startIndex = 0;
    if (hex.StartsWith("0x", StringComparison.InvariantCultureIgnoreCase))
        startIndex = 2;

    return Enumerable.Range(startIndex, hex.Length - startIndex)
                     .Where(x => x % 2 == 0)
                     .Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
                     .ToArray();
}

public static string ByteArrayToString(byte[] arr)
{
    return "0x" + BitConverter.ToString(arr).Replace("-", String.Empty);
}