curl -X POST https://cvm.tencentcloudapi.com \\
-H "Authorization: TC3-HMAC-SHA256 Credential=AKIDz8krbsJ5**********mLPx3EXAMPLE/2019-02-25/cvm/tc3_request, SignedHeaders=content-type;host, Signature=72e494ea8******************************************a96525168" \\
-H "Content-Type: application/json; charset=utf-8" \\
-H "Host: cvm.tencentcloudapi.com" \\
-H "X-TC-Action: DescribeInstances" \\
-H "X-TC-Timestamp: 1551113065" \\
-H "X-TC-Version: 2017-03-12" \\
-H "X-TC-Region: ap-guangzhou" \\
-d '{"Limit": 1, "Filters": [{"Values": ["\\u672a\\u547d\\u540d"], "Name": "instance-name"}]}'

CanonicalRequest =
    HTTPRequestMethod + '\\n' +
    CanonicalURI + '\\n' +
    CanonicalQueryString + '\\n' +
    CanonicalHeaders + '\\n' +
    SignedHeaders + '\\n' +
    HashedRequestPayload

POST
/

content-type:application/json; charset=utf-8
host:cvm.tencentcloudapi.com

content-type;host
35e9c5b0e3ae67532d3c9f17ead6c90222632e5b1ff7f6e89887f1398934f064

StringToSign =
    Algorithm + \\n +
    RequestTimestamp + \\n +
    CredentialScope + \\n +
    HashedCanonicalRequest

TC3-HMAC-SHA256
1551113065
2019-02-25/cvm/tc3_request
5ffe6a04c0664d6b969fab9a13bdab201d63ee709638e2749d62a09ca18d7031

byte[] tc3SecretKey = Encoding.UTF8.GetBytes("TC3" + SECRET_KEY);
byte[] secretDate = HmacSHA256(tc3SecretKey, Encoding.UTF8.GetBytes(date));
byte[] secretService = HmacSHA256(secretDate, Encoding.UTF8.GetBytes(service));
byte[] secretSigning = HmacSHA256(secretService, Encoding.UTF8.GetBytes("tc3_request"));
byte[] signatureBytes = HmacSHA256(secretSigning, Encoding.UTF8.GetBytes(stringToSign));
string signature = BitConverter.ToString(signatureBytes).Replace("-", "").ToLower();

Authorization =
    Algorithm + ' ' +
    'Credential=' + SecretId + '/' + CredentialScope + ', ' +
    'SignedHeaders=' + SignedHeaders + ', ' +
    'Signature=' + Signature

TC3-HMAC-SHA256 Credential=AKIDz8krbsJ5**********mLPx3EXAMPLE/2019-02-25/cvm/tc3_request, SignedHeaders=content-type;host, Signature=72e494ea8******************************************a96525168

POST https://cvm.tencentcloudapi.com/
Authorization: TC3-HMAC-SHA256 Credential=AKIDz8krbsJ5**********mLPx3EXAMPLE/2019-02-25/cvm/tc3_request, SignedHeaders=content-type;host, Signature=72e494ea8******************************************a96525168
Content-Type: application/json; charset=utf-8
Host: cvm.tencentcloudapi.com
X-TC-Action: DescribeInstances
X-TC-Version: 2017-03-12
X-TC-Timestamp: 1551113065
X-TC-Region: ap-guangzhou

{"Limit": 1, "Filters": [{"Values": ["\\u672a\\u547d\\u540d"], "Name": "instance-name"}]}

using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Text;

public class Application {
    public static string SHA256Hex(string s)
    {
        using (SHA256 algo = SHA256.Create())
        {
            byte[] hashbytes = algo.ComputeHash(Encoding.UTF8.GetBytes(s));
            StringBuilder builder = new StringBuilder();
            for (int i = 0; i < hashbytes.Length; ++i)
            {
                builder.Append(hashbytes[i].ToString("x2"));
            }
            return builder.ToString();
        }
    }
    public static byte[] HmacSHA256(byte[] key, byte[] msg)
    {
        using (HMACSHA256 mac = new HMACSHA256(key))
        {
            return mac.ComputeHash(msg);
        }
    }
    public static void Main(string[] args)
    {

        // シークレットキーパラメータ
        string SECRET_ID = "AKIDz8krbsJ5**********mLPx3EXAMPLE";
        string SECRET_KEY = "Gu5t9xGAR***********EXAMPLE";


        string service = "cvm";
        string endpoint = "cvm.tencentcloudapi.com";
        string region = "ap-guangzhou";
        string action = "DescribeInstances";
        string version = "2017-03-12";
        string algorithm = "TC3-HMAC-SHA256";
        string contentType = "application/json";
        double RequestTimestamp = 1551113065;  // タイムスタンプ 2019-02-26 00:44:25、このパラメータはサンプルであり、実際の値に基づいてください
        // long timestamp = ToTimestamp() / 1000;
        // string requestTimestamp = timestamp.ToString();
        string date = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc).AddSeconds(RequestTimestamp).ToString("yyyy-MM-dd");
        // タイムゾーンに注意してください。さもないとエラーが発生しやすくなります

        // ************* ステップ 1：正規リクエスト文字列の連結 *************
        string httpRequestMethod = "POST";
        string canonicalUri = "/";
        string canonicalQueryString = "";
        string canonicalHeaders = "content-type:" + contentType +"; charset=utf-8\\n" + "host:" + endpoint + "\\n";
        string signedHeaders = "content-type;host";
        string requestPayload = "{\\"Limit\\": 1, \\"Filters\\": [{\\"Values\\": [\\"\\\\u672a\\\\u547d\\\\u540d\\"], \\"Name\\": \\"instance-name\\"}]}";
        string hashedRequestPayload = SHA256Hex(requestPayload);
        string canonicalRequest = httpRequestMethod + "\\n"
            + canonicalUri + "\\n"
            + canonicalQueryString + "\\n"
            + canonicalHeaders + "\\n"
            + signedHeaders + "\\n"
            + hashedRequestPayload;
        Console.WriteLine(canonicalRequest);
        Console.WriteLine("----------------------------------");

        // ************* ステップ 2：署名対象文字列を連結する *************
        string credentialScope = date + "/" + service + "/" + "tc3_request";
        string hashedCanonicalRequest = SHA256Hex(canonicalRequest);
        string stringToSign = algorithm + "\\n" + RequestTimestamp + "\\n" + credentialScope + "\\n" + hashedCanonicalRequest;
        Console.WriteLine(stringToSign);
        Console.WriteLine("----------------------------------");

        // ************* ステップ 3：署名を計算する *************
        byte[] tc3SecretKey = Encoding.UTF8.GetBytes("TC3" + SECRET_KEY);
        byte[] secretDate = HmacSHA256(tc3SecretKey, Encoding.UTF8.GetBytes(date));
        byte[] secretService = HmacSHA256(secretDate, Encoding.UTF8.GetBytes(service));
        byte[] secretSigning = HmacSHA256(secretService, Encoding.UTF8.GetBytes("tc3_request"));
        byte[] signatureBytes = HmacSHA256(secretSigning, Encoding.UTF8.GetBytes(stringToSign));
        string signature = BitConverter.ToString(signatureBytes).Replace("-", "").ToLower();
        Console.WriteLine(signature);
        Console.WriteLine("----------------------------------");

        // ************* ステップ 4：Authorizationを連結する *************
        string authorization = algorithm + " "
            + "Credential=" + SECRET_ID + "/" + credentialScope + ", "
            + "SignedHeaders=" + signedHeaders + ", "
            + "Signature=" + signature;
        Console.WriteLine(authorization);
        Console.WriteLine("----------------------------------");

        Dictionary<string, string> headers = new Dictionary<string, string>();
        headers.Add("Authorization", authorization);
        headers.Add("Host", endpoint);
        headers.Add("Content-Type", contentType + "; charset=utf-8");
        headers.Add("X-TC-Timestamp", RequestTimestamp.ToString());
        headers.Add("X-TC-Version", version);
        headers.Add("X-TC-Action", action);
        headers.Add("X-TC-Region", region);
        Console.WriteLine("POST https://cvm.tencentcloudapi.com");
        foreach (KeyValuePair<string, string> kv in headers)
        {
            Console.WriteLine(kv.Key + ": " + kv.Value);
        }
        Console.WriteLine();
        Console.WriteLine(requestPayload);
    }
}

{
    'Action' : 'DescribeInstances',
    'InstanceIds.0' : 'ins-09dx96dg',
    'Limit' : 20,
    'Nonce' : 11886,  
    'Offset' : 0,
    'Region' : 'ap-guangzhou',
    'SecretId' : 'AKIDz8krbsJ5**********mLPx3EXAMPLE',
    'Timestamp' : 1465185768,
    'Version': '2017-03-12',
}

Action=DescribeInstances&InstanceIds.0=ins-09dx96dg&Limit=20&Nonce=11886&Offset=0&Region=ap-guangzhou&SecretId=AKIDz8krbsJ5**********mLPx3EXAMPLE&Timestamp=1465185768&Version=2017-03-12

GETcvm.tencentcloudapi.com/?Action=DescribeInstances&InstanceIds.0=ins-09dx96dg&Limit=20&Nonce=11886&Offset=0&Region=ap-guangzhou&SecretId=AKIDz8krbsJ5**********mLPx3EXAMPLE&Timestamp=1465185768&Version=2017-03-12

public static string Sign(string signKey, string secret, string SignatureMethod)
    {
        string signRet = string.Empty;
        using (HMACSHA1 mac = new HMACSHA1(Encoding.UTF8.GetBytes(signKey)))
        {
            byte[] hash = mac.ComputeHash(Encoding.UTF8.GetBytes(secret));
            signRet = Convert.ToBase64String(hash);
        }
        return signRet;
    }

# 実際の呼び出し、成功した場合、消費型APIであれば課金が発生する可能性があります（ここではPython言語を例としてgetリクエストを送信します）
resp = requests.get("https://" + endpoint, params=data)
print(resp.url)

最終的に得られるリクエスト文字列は
https://cvm.tencentcloudapi.com/?Action=DescribeInstances&InstanceIds.0=ins-09dx96dg&Limit=20&Nonce=11886&Offset=0&Region=ap-guangzhou&SecretId=AKIDz8krbsJ5**********mLPx3EXAMPLE&Signature=EliP9YW3pW28FpsEdkXt%2F%2BWcGeI%3D&Timestamp=1465185768&Version=2017-03-12

using System;
using System.Collections.Generic;
using System.Net;
using System.Security.Cryptography;
using System.Text;

public class Application {
    public static string Sign(string signKey, string secret)
    {
        string signRet = string.Empty;
            using (HMACSHA1 mac = new HMACSHA1(Encoding.UTF8.GetBytes(signKey)))
            {
                byte[] hash = mac.ComputeHash(Encoding.UTF8.GetBytes(secret));
                signRet = Convert.ToBase64String(hash);
            }
        return signRet;
    }
    public static string MakeSignPlainText(SortedDictionary<string, string> requestParams, string requestMethod, string requestHost, string requestPath)
    {
        string retStr = "";
        retStr += requestMethod;
        retStr += requestHost;
        retStr += requestPath;
        retStr += "?";
        string v = "";
        foreach (string key in requestParams.Keys)
        {
            v += string.Format("{0}={1}&", key, requestParams[key]);
        }
        retStr += v.TrimEnd('&');
        return retStr;
    }

    public static void Main(string[] args)
    {
        // シークレットキーパラメータ
        string SECRET_ID = "AKIDz8krbsJ5**********mLPx3EXAMPLE";
        string SECRET_KEY = "Gu5t9xGAR***********EXAMPLE";

        string endpoint = "cvm.tencentcloudapi.com";
        string region = "ap-guangzhou";
        string action = "DescribeInstances";
        string version = "2017-03-12";
        double RequestTimestamp = 1465185768;  // タイムスタンプ 2019-02-26 00:44:25、このパラメータはサンプルであり、実際の値に基づいてください
        // long timestamp = ToTimestamp() / 1000;
        // string requestTimestamp = timestamp.ToString();
        Dictionary<string, string> param = new Dictionary<string, string>();
        param.Add("Limit", "20");
        param.Add("Offset", "0");
        param.Add("InstanceIds.0", "ins-09dx96dg");
        param.Add("Action", action);
        param.Add("Nonce", "11886");
        // param.Add("Nonce", Math.Abs(new Random().Next()).ToString());

        param.Add("Timestamp", RequestTimestamp.ToString());
        param.Add("Version", version);

        param.Add("SecretId", SECRET_ID);
        param.Add("Region", region);
        SortedDictionary<string, string> headers = new SortedDictionary<string, string>(param, StringComparer.Ordinal);
        string sigInParam = MakeSignPlainText(headers, "GET", endpoint, "/");
        Console.WriteLine(sigInParam);
        string sigOutParam = Sign(SECRET_KEY, sigInParam);


        Console.WriteLine("GET https://cvm.tencentcloudapi.com");
        foreach (KeyValuePair<string, string> kv in headers)
        {
            Console.WriteLine(kv.Key + ": " + kv.Value);
        }
        Console.WriteLine("Signature" + ": " + WebUtility.UrlEncode(sigOutParam));
        Console.WriteLine();

        string result = "https://cvm.tencentcloudapi.com/?";
        foreach (KeyValuePair<string, string> kv in headers)
        {
            result += WebUtility.UrlEncode(kv.Key) + "=" + WebUtility.UrlEncode(kv.Value) + "&";
        }
        result += WebUtility.UrlEncode("Signature") + "=" + WebUtility.UrlEncode(sigOutParam);
        Console.WriteLine("GET " + result);
    }
}

{
    "Response": {
        "TotalCount": 0,
        "InstanceStatusSet": [],
        "RequestId": "b5b41468-520d-4192-b42f-595cc34b6c1c"
    }
}

{
    "Response": {
        "Error": {
            "Code": "AuthFailure.SignatureFailure",
            "Message": "The provided credentials could not be validated. Please check your signature is correct."
        },
        "RequestId": "ed93f3cb-f35e-473f-b9f3-0d451b8b79c6"
    }
}