OAuth 1.0 library recommended by NetSuite for c#

OAuthBase.cs

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

// https://gist.github.com/ecounysis/7889b67704a26f26369399a636105233
// https://netsuite.custhelp.com/app/answers/detail/a_id/42169/kw/C%23%20>%20RESTlet%20Authentication%20Using%20Token%20(Token-Based%20Authentication)

namespace OAuth
{
  public class OAuthBase
  {
    /// <summary>
    /// Provides a predefined set of algorithms that are supported officially by the protocol
    /// </summary>
    public enum SignatureTypes
    {
      HMACSHA1,
      PLAINTEXT,
      RSASHA1
    }

    /// <summary>
    /// Provides an internal structure to sort the query parameter
    /// </summary>
    protected class QueryParameter
    {
      private string name = null;
      private string value = null;

      public QueryParameter(string name, string value)
      {
        this.name = name;
        this.value = value;
      }

      public string Name
      {
        get { return name; }
      }

      public string Value
      {
        get { return value; }
      }
    }

    /// <summary>
    /// Comparer class used to perform the sorting of the query parameters
    /// </summary>
    protected class QueryParameterComparer : IComparer<QueryParameter>

    {

      #region IComparer<QueryParameter> Members

      public int Compare(QueryParameter x, QueryParameter y)

      {
        if (x.Name == y.Name)
        {
          return string.Compare(x.Value, y.Value);
        }
        else
        {
          return string.Compare(x.Name, y.Name);
        }
      }

      #endregion
    }

    protected const string OAuthVersion = "1.0";
    protected const string OAuthParameterPrefix = "oauth_";

    //
    // List of know and used oauth parameters' names
    //        
    protected const string OAuthConsumerKeyKey = "oauth_consumer_key";
    protected const string OAuthCallbackKey = "oauth_callback";
    protected const string OAuthVersionKey = "oauth_version";
    protected const string OAuthSignatureMethodKey = "oauth_signature_method";
    protected const string OAuthSignatureKey = "oauth_signature";
    protected const string OAuthTimestampKey = "oauth_timestamp";
    protected const string OAuthNonceKey = "oauth_nonce";
    protected const string OAuthTokenKey = "oauth_token";
    protected const string OAuthTokenSecretKey = "oauth_token_secret";

    protected const string HMACSHA1SignatureType = "HMAC-SHA1";
    protected const string PlainTextSignatureType = "PLAINTEXT";
    protected const string RSASHA1SignatureType = "RSA-SHA1";

    protected Random random = new Random();

    protected string unreservedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.~";

    /// <summary>
    /// Helper function to compute a hash value
    /// </summary>
    /// <param name="hashAlgorithm">The hashing algoirhtm used. If that algorithm needs some initialization, like HMAC and its derivatives, they should be initialized prior to passing it to this function</param>
    /// <param name="data">The data to hash</param>
    /// <returns>a Base64 string of the hash value</returns>
    private string ComputeHash(HashAlgorithm hashAlgorithm, string data)

    {
      if (hashAlgorithm == null)

      {
        throw new ArgumentNullException("hashAlgorithm");
      }

      if (string.IsNullOrEmpty(data))

      {
        throw new ArgumentNullException("data");
      }

      byte[] dataBuffer = System.Text.Encoding.ASCII.GetBytes(data);
      byte[] hashBytes = hashAlgorithm.ComputeHash(dataBuffer);

      return Convert.ToBase64String(hashBytes);
    }

    /// <summary>
    /// Internal function to cut out all non oauth query string parameters (all parameters not begining with "oauth_")
    /// </summary>
    /// <param name="parameters">The query string part of the Url</param>
    /// <returns>A list of QueryParameter each containing the parameter name and value</returns>
    private List<QueryParameter> GetQueryParameters(string parameters)

    {
      if (parameters.StartsWith("?"))
      {
        parameters = parameters.Remove(0, 1);
      }

      List<QueryParameter> result = new List<QueryParameter>();

      if (!string.IsNullOrEmpty(parameters))

      {
        string[] p = parameters.Split('&');
        foreach (string s in p)
        {
          if (!string.IsNullOrEmpty(s) && !s.StartsWith(OAuthParameterPrefix))

          {
            if (s.IndexOf('=') > -1)

            {
              string[] temp = s.Split('=');
              result.Add(new QueryParameter(temp[0], temp[1]));
            }
            else

            {
              result.Add(new QueryParameter(s, string.Empty));
            }
          }
        }
      }

      return result;
    }

    /// <summary>
    /// This is a different Url Encode implementation since the default .NET one outputs the percent encoding in lower case.
    /// While this is not a problem with the percent encoding spec, it is used in upper case throughout OAuth
    /// </summary>
    /// <param name="value">The value to Url encode</param>
    /// <returns>Returns a Url encoded string</returns>
    protected string UrlEncode(string value)

    {
      StringBuilder result = new StringBuilder();

      foreach (char symbol in value)

      {
        if (unreservedChars.IndexOf(symbol) != -1)

        {
          result.Append(symbol);
        }
        else

        {
          result.Append('%' + String.Format("{0:X2}", (int)symbol));
        }
      }

      return result.ToString();
    }

    /// <summary>
    /// Normalizes the request parameters according to the spec
    /// </summary>
    /// <param name="parameters">The list of parameters already sorted</param>
    /// <returns>a string representing the normalized parameters</returns>
    protected string NormalizeRequestParameters(IList<QueryParameter> parameters)
    {
      StringBuilder sb = new StringBuilder();
      QueryParameter p = null;
      for (int i = 0; i < parameters.Count; i++)

      {
        p = parameters[i];
        sb.AppendFormat("{0}={1}", p.Name, p.Value);

        if (i < parameters.Count - 1)

        {
          sb.Append("&");
        }
      }

      return sb.ToString();
    }

    /// <summary>
    /// Generate the signature base that is used to produce the signature
    /// </summary>
    /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
    /// <param name="consumerKey">The consumer key</param>        
    /// <param name="token">The token, if available. If not available pass null or an empty string</param>
    /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
    /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
    /// <param name="signatureType">The signature type. To use the default values use <see cref="OAuthBase.SignatureTypes">OAuthBase.SignatureTypes</see>.</param>
    /// <returns>The signature base</returns>
    public string GenerateSignatureBase(Uri url, string consumerKey, string token, string tokenSecret, string httpMethod, string timeStamp, string nonce, string signatureType, out string normalizedUrl, out string normalizedRequestParameters)
    {
      if (token == null)
      {
        token = string.Empty;
      }

      if (tokenSecret == null)
      {
        tokenSecret = string.Empty;
      }

      if (string.IsNullOrEmpty(consumerKey))
      {
        throw new ArgumentNullException("consumerKey");
      }

      if (string.IsNullOrEmpty(httpMethod))
      {
        throw new ArgumentNullException("httpMethod");
      }

      if (string.IsNullOrEmpty(signatureType))
      {
        throw new ArgumentNullException("signatureType");
      }

      normalizedUrl = null;
      normalizedRequestParameters = null;

      List<QueryParameter> parameters = GetQueryParameters(url.Query);
      parameters.Add(new QueryParameter(OAuthVersionKey, OAuthVersion));
      parameters.Add(new QueryParameter(OAuthNonceKey, nonce));
      parameters.Add(new QueryParameter(OAuthTimestampKey, timeStamp));
      parameters.Add(new QueryParameter(OAuthSignatureMethodKey, signatureType));
      parameters.Add(new QueryParameter(OAuthConsumerKeyKey, consumerKey));

      if (!string.IsNullOrEmpty(token))
      {
        parameters.Add(new QueryParameter(OAuthTokenKey, token));
      }

      parameters.Sort(new QueryParameterComparer());

      normalizedUrl = string.Format("{0}://{1}", url.Scheme, url.Host);
      if (!((url.Scheme == "http" && url.Port == 80) || (url.Scheme == "https" && url.Port == 443)))

      {
        normalizedUrl += ":" + url.Port;
      }
      normalizedUrl += url.AbsolutePath;
      normalizedRequestParameters = NormalizeRequestParameters(parameters);

      StringBuilder signatureBase = new StringBuilder();
      signatureBase.AppendFormat("{0}&", httpMethod.ToUpper());
      signatureBase.AppendFormat("{0}&", UrlEncode(normalizedUrl));
      signatureBase.AppendFormat("{0}", UrlEncode(normalizedRequestParameters));

      return signatureBase.ToString();
    }

    /// <summary>
    /// Generate the signature value based on the given signature base and hash algorithm
    /// </summary>
    /// <param name="signatureBase">The signature based as produced by the GenerateSignatureBase method or by any other means</param>
    /// <param name="hash">The hash algorithm used to perform the hashing. If the hashing algorithm requires initialization or a key it should be set prior to calling this method</param>
    /// <returns>A base64 string of the hash value</returns>
    public string GenerateSignatureUsingHash(string signatureBase, HashAlgorithm hash)
    {
      return ComputeHash(hash, signatureBase);
    }

    /// <summary>
    /// Generates a signature using the HMAC-SHA1 algorithm
    /// </summary>      
    /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
    /// <param name="consumerKey">The consumer key</param>
    /// <param name="consumerSecret">The consumer seceret</param>
    /// <param name="token">The token, if available. If not available pass null or an empty string</param>
    /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
    /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
    /// <returns>A base64 string of the hash value</returns>
    public string GenerateSignature(Uri url, string consumerKey, string consumerSecret, string token, string tokenSecret, string httpMethod, string timeStamp, string nonce, out string normalizedUrl, out string normalizedRequestParameters)
    {
      return GenerateSignature(url, consumerKey, consumerSecret, token, tokenSecret, httpMethod, timeStamp, nonce, SignatureTypes.HMACSHA1, out normalizedUrl, out normalizedRequestParameters);
    }

    /// <summary>
    /// Generates a signature using the specified signatureType 
    /// </summary>      
    /// <param name="url">The full url that needs to be signed including its non OAuth url parameters</param>
    /// <param name="consumerKey">The consumer key</param>
    /// <param name="consumerSecret">The consumer seceret</param>
    /// <param name="token">The token, if available. If not available pass null or an empty string</param>
    /// <param name="tokenSecret">The token secret, if available. If not available pass null or an empty string</param>
    /// <param name="httpMethod">The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)</param>
    /// <param name="signatureType">The type of signature to use</param>
    /// <returns>A base64 string of the hash value</returns>
    public string GenerateSignature(Uri url, string consumerKey, string consumerSecret, string token, string tokenSecret, string httpMethod, string timeStamp, string nonce, SignatureTypes signatureType, out string normalizedUrl, out string normalizedRequestParameters)
    {
      normalizedUrl = null;
      normalizedRequestParameters = null;

      switch (signatureType)
      {
        case SignatureTypes.PLAINTEXT:
          return UrlEncode(string.Format("{0}&{1}", consumerSecret, tokenSecret));
        case SignatureTypes.HMACSHA1:
          string signatureBase = GenerateSignatureBase(url, consumerKey, token, tokenSecret, httpMethod, timeStamp, nonce, HMACSHA1SignatureType, out normalizedUrl, out normalizedRequestParameters);

          HMACSHA1 hmacsha1 = new HMACSHA1();
          hmacsha1.Key = Encoding.ASCII.GetBytes(string.Format("{0}&{1}", UrlEncode(consumerSecret), string.IsNullOrEmpty(tokenSecret) ? "" : UrlEncode(tokenSecret)));

          return GenerateSignatureUsingHash(signatureBase, hmacsha1);
        case SignatureTypes.RSASHA1:
          throw new NotImplementedException();
        default:
          throw new ArgumentException("Unknown signature type", "signatureType");
      }
    }

    /// <summary>
    /// Generate the timestamp for the signature        
    /// </summary>
    /// <returns></returns>
    public virtual string GenerateTimeStamp()
    {
      // Default implementation of UNIX time of the current UTC time
      TimeSpan ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
      return Convert.ToInt64(ts.TotalSeconds).ToString();
    }

    /// <summary>
    /// Generate a nonce
    /// </summary>
    /// <returns></returns>
    public virtual string GenerateNonce()
    {
      // Just a simple implementation of a random number between 123400 and 9999999
      return random.Next(123400, 9999999).ToString();
    }

  }
}

tried this code to call, getting Invalid "INVALID_LOGIN_ATTEMPT". In Postman it works. am I missing anything?

`

 //string netsuite_base_url = "https://test-sb1.restlets.api.netsuite.com/app/site/hosting/restlet.nl? 
     script=941&deploy=1&FC=SGD&TC=USD&ED=02/11/2022";

void option3()
{
var netsuiteHelper = new OAuthBase();

var normalizedurl = "";
var normallizedRequestParam = "";
var timeStamp = netsuiteHelper.GenerateTimeStamp();
var nounce = netsuiteHelper.GenerateNonce();
string signature = netsuiteHelper.GenerateSignature(new Uri(netsuite_base_url), consumerKey, ConsumerSecret, TokenId, TokenSecret, "GET", timeStamp, nounce,
    OAuthBase.SignatureTypes.HMACSHA1, out normalizedurl, out normallizedRequestParam);

var netSuiteAuthorization = "OAuth " +
     "realm=" + "\"" + realm + "\"" + "," +
     "oauth_consumer_key=" + "\"" + consumerKey + "\"" + "," +
     "oauth_token=" + "\"" + TokenId + "\"" + "," +
     "oauth_signature_method=" + "\"" + "HMAC-SHA256" + "\"" + "," +
     "oauth_timestamp=" + "\"" + timeStamp + "\"" + "," +
     "oauth_nonce=" + "\"" + nounce + "\"" + "," +
     "oauth_version=" + "\"" + "1.0" + "\"" + "," +
     "oauth_signature= " + "\"" + signature + "\"";

var client = new RestClient(netsuite_base_url);
var request = new RestRequest();

request.AddHeader("Authorization", netSuiteAuthorization);
request.AddHeader("Content-Type", "application/json");

var response = client.Execute(request);

Console.WriteLine(response.Content);
}

`

I have the same problem

tried this code to call, getting Invalid "INVALID_LOGIN_ATTEMPT". In Postman it works. am I missing anything?
`

 //string netsuite_base_url = "https://test-sb1.restlets.api.netsuite.com/app/site/hosting/restlet.nl? 
     script=941&deploy=1&FC=SGD&TC=USD&ED=02/11/2022";

void option3()
{
var netsuiteHelper = new OAuthBase();

var normalizedurl = "";
var normallizedRequestParam = "";
var timeStamp = netsuiteHelper.GenerateTimeStamp();
var nounce = netsuiteHelper.GenerateNonce();
string signature = netsuiteHelper.GenerateSignature(new Uri(netsuite_base_url), consumerKey, ConsumerSecret, TokenId, TokenSecret, "GET", timeStamp, nounce,
    OAuthBase.SignatureTypes.HMACSHA1, out normalizedurl, out normallizedRequestParam);

var netSuiteAuthorization = "OAuth " +
     "realm=" + "\"" + realm + "\"" + "," +
     "oauth_consumer_key=" + "\"" + consumerKey + "\"" + "," +
     "oauth_token=" + "\"" + TokenId + "\"" + "," +
     "oauth_signature_method=" + "\"" + "HMAC-SHA256" + "\"" + "," +
     "oauth_timestamp=" + "\"" + timeStamp + "\"" + "," +
     "oauth_nonce=" + "\"" + nounce + "\"" + "," +
     "oauth_version=" + "\"" + "1.0" + "\"" + "," +
     "oauth_signature= " + "\"" + signature + "\"";

var client = new RestClient(netsuite_base_url);
var request = new RestRequest();

request.AddHeader("Authorization", netSuiteAuthorization);
request.AddHeader("Content-Type", "application/json");

var response = client.Execute(request);

Console.WriteLine(response.Content);
}

`

I have the same problem

It looks like your issue was you were making your signature with HMACSHA1, but specifying HMAC-SHA256 in your oauth_signature_method. I modified the code slightly to add support for HMAC-SHA256 as a signature method, and it worked for me.

I added this as a valid signature method:
public enum SignatureTypes
{
HMACSHA1,
PLAINTEXT,
RSASHA1,
HMACSHA256
}

Then added this line with the other const definitions:
protected const string HMACSHA256SignatureType = "HMAC-SHA256";

finally, updated this procedure:
public string GenerateSignature(Uri url, string consumerKey, string consumerSecret, string token, string tokenSecret, string httpMethod, string timeStamp, string nonce, SignatureTypes signatureType, out string normalizedUrl, out string normalizedRequestParameters)
{
normalizedUrl = null;
normalizedRequestParameters = null;
string signatureBase = "";

        switch (signatureType)
        {
            case SignatureTypes.PLAINTEXT:
                return UrlEncode(string.Format("{0}&{1}", consumerSecret, tokenSecret));
            case SignatureTypes.HMACSHA1:
                signatureBase = GenerateSignatureBase(url, consumerKey, token, tokenSecret, httpMethod, timeStamp, nonce, HMACSHA1SignatureType, out normalizedUrl, out normalizedRequestParameters);

                HMACSHA1 hmacsha1 = new HMACSHA1();
                hmacsha1.Key = Encoding.ASCII.GetBytes(string.Format("{0}&{1}", UrlEncode(consumerSecret), string.IsNullOrEmpty(tokenSecret) ? "" : UrlEncode(tokenSecret)));

                return GenerateSignatureUsingHash(signatureBase, hmacsha1);
            case SignatureTypes.RSASHA1:
                throw new NotImplementedException();
            case SignatureTypes.HMACSHA256:
                signatureBase = GenerateSignatureBase(url, consumerKey, token, tokenSecret, httpMethod, timeStamp, nonce, HMACSHA256SignatureType, out normalizedUrl, out normalizedRequestParameters);

                HMACSHA256 hmacsha256 = new HMACSHA256();
                hmacsha256.Key = Encoding.ASCII.GetBytes(string.Format("{0}&{1}", UrlEncode(consumerSecret), string.IsNullOrEmpty(tokenSecret) ? "" : UrlEncode(tokenSecret)));

                return GenerateSignatureUsingHash(signatureBase, hmacsha256);
            default:
                throw new ArgumentException("Unknown signature type", "signatureType");
        }
    }

In the Signature Call code, I changed as follows:
string signature = netsuiteHelper.GenerateSignature(new Uri(URL), ConsumerKey, ConsumerSecret, AccessToken, TokenSecret, "POST", timeStamp, nounce, OAuthBase.SignatureTypes.HMACSHA256, out normalizedurl, out normallizedRequestParam);