using System;
using System.Security.Cryptography;
using System.Collections.Generic;
using System.Text;
namespace OAuth {
public class OAuthBase {
///
/// Provides a predefined set of algorithms that are supported officially by the protocol
///
public enum SignatureTypes {
HMACSHA1,
PLAINTEXT,
RSASHA1
}
///
/// Provides an internal structure to sort the query parameter
///
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; }
}
}
///
/// Comparer class used to perform the sorting of the query parameters
///
protected class QueryParameterComparer : IComparer {
#region IComparer 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 OAuthVerifier = "oauth_verifier";
protected const string HMACSHA1SignatureType = "HMAC-SHA1";
protected const string PlainTextSignatureType = "PLAINTEXT";
protected const string RSASHA1SignatureType = "RSA-SHA1";
protected static string unreservedChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.~";
///
/// Helper function to compute a hash value
///
/// 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
/// The data to hash
/// a Base64 string of the hash value
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);
}
///
/// Internal function to cut out all non oauth query string parameters (all parameters not begining with "oauth_")
///
/// The query string part of the Url
/// A list of QueryParameter each containing the parameter name and value
private List GetQueryParameters(string parameters) {
if (parameters.StartsWith("?")) {
parameters = parameters.Remove(0, 1);
}
List result = new List();
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;
}
///
/// 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
///
/// The value to Url encode
/// Returns a Url encoded string
public static 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();
}
///
/// Normalizes the request parameters according to the spec
///
/// The list of parameters already sorted
/// a string representing the normalized parameters
protected string NormalizeRequestParameters(IList 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();
}
///
/// Generate the signature base that is used to produce the signature
///
/// The full url that needs to be signed including its non OAuth url parameters
/// The callback URL, if available.
/// The consumer key
/// The token, if available. If not available pass null or an empty string
/// The token secret, if available. If not available pass null or an empty string
/// The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)
/// The signature type. To use the default values use OAuthBase.SignatureTypes.
/// The signature base
public string GenerateSignatureBase(Uri url, string callback, string consumerKey, string token, string tokenSecret, string httpMethod, string timeStamp, string verifier, string nonce, string signatureType, out string normalizedUrl, out string normalizedRequestParameters) {
if (callback == null) {
callback = string.Empty;
}
if (token == null) {
token = string.Empty;
}
if (tokenSecret == null) {
tokenSecret = string.Empty;
}
if (verifier == null) {
verifier = 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 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));
}
if (!string.IsNullOrEmpty(callback)) {
parameters.Add(new QueryParameter(OAuthCallbackKey, UrlEncode(callback)));
}
if (!string.IsNullOrEmpty(verifier))
{
parameters.Add(new QueryParameter(OAuthVerifier, verifier));
}
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();
}
///
/// Generate the signature value based on the given signature base and hash algorithm
///
/// The signature based as produced by the GenerateSignatureBase method or by any other means
/// 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
/// A base64 string of the hash value
public string GenerateSignatureUsingHash(string signatureBase, HashAlgorithm hash) {
return ComputeHash(hash, signatureBase);
}
///
/// Generates a signature using the HMAC-SHA1 algorithm
///
/// The full url that needs to be signed including its non OAuth url parameters
/// The consumer key
/// The consumer seceret
/// The token, if available. If not available pass null or an empty string
/// The token secret, if available. If not available pass null or an empty string
/// The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)
/// A base64 string of the hash value
public string GenerateSignature(Uri url, string callback, string consumerKey, string consumerSecret, string token, string tokenSecret, string httpMethod, string timeStamp, string verifier, string nonce, out string normalizedUrl, out string normalizedRequestParameters) {
return GenerateSignature(url, callback, consumerKey, consumerSecret, token, tokenSecret, httpMethod, timeStamp, verifier, nonce, SignatureTypes.HMACSHA1, out normalizedUrl, out normalizedRequestParameters);
}
///
/// Generates a signature using the specified signatureType
///
/// The full url that needs to be signed including its non OAuth url parameters
/// The consumer key
/// The consumer seceret
/// The token, if available. If not available pass null or an empty string
/// The token secret, if available. If not available pass null or an empty string
/// The http method used. Must be a valid HTTP method verb (POST,GET,PUT, etc)
/// The type of signature to use
/// A base64 string of the hash value
public string GenerateSignature(Uri url, string callback, string consumerKey, string consumerSecret, string token, string tokenSecret, string httpMethod, string timeStamp, string verifier, 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, callback, consumerKey, token, tokenSecret, httpMethod, timeStamp, verifier, 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");
}
}
///
/// Generate the timestamp for the signature
///
///
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();
}
///
/// Generate a nonce
///
///
public virtual string GenerateNonce() {
return Guid.NewGuid().ToString().Replace("-", "");
}
}
}