using System;
using System.Security.Cryptography;
using System.Collections.Generic;
using System.Text;
using System.Web; 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 HttpUtility.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();
} }
}