Exemplo n.º 1
0
        /// <summary>
        /// Returns the string representation of the bewit, which is a base64 URL encoded string of format
        /// id\exp\mac\ext, where id is the user identifier, exp is the UNIX time until which bewit is
        /// valid, mac is the HMAC of the bewit to protect integrity, and ext is the application specific data.
        /// </summary>
        public string ToBewitString()
        {
            if (request.Method != HttpMethod.Get) // Not supporting HEAD
                throw new InvalidOperationException("Bewit not allowed for methods other than GET");

            ulong now = utcNow.ToUnixTime() + Convert.ToUInt64(this.localOffset);

            var artifacts = new ArtifactsContainer()
            {
                Id = credential.Id,
                Timestamp = now + (ulong)lifeSeconds,
                Nonce = String.Empty,
                ApplicationSpecificData = this.applicationSpecificData ?? String.Empty
            };

            var normalizedRequest = new NormalizedRequest(request, artifacts) { IsBewit = true };
            var crypto = new Cryptographer(normalizedRequest, artifacts, credential);

            // Sign the request
            crypto.Sign(); // Bewit is for GET and GET must have no request body

            // bewit: id\exp\mac\ext
            string bewit = String.Format(@"{0}\{1}\{2}\{3}",
                                credential.Id,
                                artifacts.Timestamp,
                                artifacts.Mac.ToBase64String(),
                                artifacts.ApplicationSpecificData);

            return bewit.ToBytesFromUtf8().ToBase64UrlString();
        }
        /// <summary>
        /// Returns an AuthenticationResult object corresponding to the result of authentication done
        /// using the client supplied artifacts in the HTTP authorization header in hawk scheme.
        /// </summary>
        /// <param name="now">Current UNIX time in milliseconds.</param>
        /// <param name="request">Request object.</param>
        /// <param name="options">Hawk authentication options</param>
        /// <returns></returns>
        internal static async Task<AuthenticationResult> AuthenticateAsync(ulong now, IRequestMessage request, Options options)
        {
            ArtifactsContainer artifacts = null;
            Credential credential = null;

            if (request.HasValidHawkScheme())
            {
                if (ArtifactsContainer.TryParse(request.Authorization.Parameter, out artifacts))
                {
                    if (artifacts != null && artifacts.AreClientArtifactsValid)
                    {
                        credential = options.CredentialsCallback(artifacts.Id);
                        if (credential != null && credential.IsValid)
                        {
                            var normalizedRequest = new NormalizedRequest(request, artifacts);
                            var crypto = new Cryptographer(normalizedRequest, artifacts, credential);

                            // Request body is needed only when payload hash is present in the request
                            string body = null;
                            if (artifacts.PayloadHash != null && artifacts.PayloadHash.Length > 0)
                            {
                                body = await request.ReadBodyAsStringAsync();
                            }

                            if (crypto.IsSignatureValid(body, request.ContentType)) // MAC and hash checks
                            {
                                if (IsTimestampFresh(now, artifacts, options))
                                {
                                    // If you get this far, you are authentic. Welcome and thanks for flying Hawk!
                                    return new AuthenticationResult()
                                    {
                                        IsAuthentic = true,
                                        Artifacts = artifacts,
                                        Credential = credential,
                                        ApplicationSpecificData = artifacts.ApplicationSpecificData
                                    };
                                }
                                else
                                {
                                    // Authentic but for the timestamp freshness.
                                    // Give a chance to the client to correct the clocks skew.
                                    var timestamp = new NormalizedTimestamp(DateTime.UtcNow, credential, options.LocalTimeOffsetMillis);
                                    request.ChallengeParameter = timestamp.ToWwwAuthenticateHeaderParameter();
                                }
                            }
                        }
                    }
                }
            }

            return new AuthenticationResult() { IsAuthentic = false };
        }
        /// <summary>
        /// Returns the name of the response header (WWW-Authenticate or Server-Authorization) and the corresponding
        /// value, respectively for an unauthorized and a successful request.
        /// </summary>
        public async Task<Tuple<string, string>> CreateServerAuthorizationAsync(IResponseMessage response)
        {
            if (response.StatusCode == HttpStatusCode.Unauthorized)
            {
                string challenge = String.Format(" {0}", request.ChallengeParameter ?? String.Empty);
                string headerValue = HawkConstants.Scheme + challenge.TrimEnd(' ');

                return new Tuple<string, string>(HawkConstants.WwwAuthenticateHeaderName, headerValue);
            }
            else
            {
                // No Server-Authorization header for the following:
                // (1) There is no result or failed authentication.
                // (2) The credential is a bewit.
                // (3) The server is configured to not send the header.
                bool createHeader = this.result != null
                                        && this.result.IsAuthentic
                                            && (!this.isBewitRequest)
                                                && options.EnableServerAuthorization;

                if (createHeader)
                {
                    if (options.NormalizationCallback != null)
                        this.result.Artifacts.ApplicationSpecificData = options.NormalizationCallback(response);

                    // Sign the response
                    var normalizedRequest = new NormalizedRequest(request, this.result.Artifacts, options.HostNameSource)
                    {
                        IsServerAuthorization = true
                    };
                    var crypto = new Cryptographer(normalizedRequest, this.result.Artifacts, this.result.Credential);

                    // Response body is needed only if payload hash must be included in the response MAC.
                    string body = null;
                    if (options.ResponsePayloadHashabilityCallback != null &&
                            options.ResponsePayloadHashabilityCallback(this.request))
                    {
                        body = await response.ReadBodyAsStringAsync();
                    }

                    crypto.Sign(body, response.ContentType);

                    string authorization = this.result.Artifacts.ToServerAuthorizationHeaderParameter();

                    if (!String.IsNullOrWhiteSpace(authorization))
                    {
                        return new Tuple<string, string>(HawkConstants.ServerAuthorizationHeaderName,
                            String.Format("{0} {1}", HawkConstants.Scheme, authorization));
                    }
                }
            }

            return null;
        }
        /// <summary>
        /// Returns true if the server response HMAC cannot be validated, indicating possible tampering.
        /// </summary>
        private async Task<bool> IsResponseTamperedAsync(ArtifactsContainer artifacts, Cryptographer crypto,
                                                        IResponseMessage response)
        {
            if (response.Headers.ContainsKey(HawkConstants.ServerAuthorizationHeaderName))
            {
                string header = response.Headers[HawkConstants.ServerAuthorizationHeaderName].FirstOrDefault();

                if (!String.IsNullOrWhiteSpace(header) &&
                                    header.Substring(0, HawkConstants.Scheme.Length).ToLower() == HawkConstants.Scheme)
                {
                    ArtifactsContainer serverAuthorizationArtifacts;
                    if (ArtifactsContainer.TryParse(header.Substring(HawkConstants.Scheme.Length + " ".Length),
                                                                                    out serverAuthorizationArtifacts))
                    {
                        // To validate response, ext, hash, and mac in the request artifacts must be
                        // replaced with the ones from the server.
                        artifacts.ApplicationSpecificData = serverAuthorizationArtifacts.ApplicationSpecificData;
                        artifacts.PayloadHash = serverAuthorizationArtifacts.PayloadHash;
                        artifacts.Mac = serverAuthorizationArtifacts.Mac;

                        // Response body is needed only if payload hash is present in the server response.
                        string body = null;
                        if (artifacts.PayloadHash != null && artifacts.PayloadHash.Length > 0)
                        {
                            body = await response.ReadBodyAsStringAsync();
                        }

                        bool isValid = crypto.IsSignatureValid(body, response.ContentType);

                        if (isValid)
                        {
                            string appSpecificData = serverAuthorizationArtifacts.ApplicationSpecificData;

                            isValid = options.VerificationCallback == null ||
                                                    options.VerificationCallback(response, appSpecificData);
                        }

                        return !isValid;
                    }
                }
            }

            return true; // Missing header means possible tampered response (to err on the side of caution).
        }
        /// <summary>
        /// Creates the HTTP Authorization header in hawk scheme.
        /// </summary>
        internal async Task CreateClientAuthorizationInternalAsync(IRequestMessage request, DateTime utcNow)
        {
            var credential = options.CredentialsCallback();
            this.artifacts = new ArtifactsContainer()
            {
                Id = credential.Id,
                Timestamp = utcNow.AddSeconds(HawkClient.CompensatorySeconds).ToUnixTime(),
                Nonce = NonceGenerator.Generate()
            };

            if (options.NormalizationCallback != null)
                this.artifacts.ApplicationSpecificData = options.NormalizationCallback(request);

            var normalizedRequest = new NormalizedRequest(request, this.artifacts);
            this.crypto = new Cryptographer(normalizedRequest, this.artifacts, credential);

            // Sign the request
            bool includePayloadHash = options.RequestPayloadHashabilityCallback != null &&
                                            options.RequestPayloadHashabilityCallback(request);

            string payload = includePayloadHash ? await request.ReadBodyAsStringAsync() : null;
            crypto.Sign(payload, request.ContentType);

            request.Authorization = new AuthenticationHeaderValue(HawkConstants.Scheme,
                                                this.artifacts.ToAuthorizationHeaderParameter());
        }
        /// <summary>
        /// Returns an AuthenticationResult object corresponding to the result of authentication done
        /// using the client supplied artifacts in the HTTP authorization header in hawk scheme.
        /// </summary>
        /// <param name="now">Current UNIX time in milliseconds.</param>
        /// <param name="request">Request object.</param>
        /// <param name="options">Hawk authentication options</param>
        /// <returns></returns>
        internal static async Task<AuthenticationResult> AuthenticateAsync(ulong now, IRequestMessage request, Options options)
        {
            ArtifactsContainer artifacts = null;
            Credential credential = null;

            if (request.HasValidHawkScheme())
            {
                if (ArtifactsContainer.TryParse(request.Authorization.Parameter, out artifacts))
                {
                    if (artifacts != null && artifacts.AreClientArtifactsValid)
                    {
                        string lastUsedBy = options.DetermineNonceReplayCallback(artifacts.Nonce);

                        if (String.IsNullOrEmpty(lastUsedBy)) // Not an old nonce, and hence not a replay.
                        {
                            credential = options.CredentialsCallback(artifacts.Id);
                            if (credential != null && credential.IsValid)
                            {
                                HawkEventSource.Log.Debug(
                                    String.Format("Algorithm={0} Key={1} ID={2}",
                                                        credential.Algorithm.ToString(),
                                                        Convert.ToBase64String(credential.Key),
                                                        credential.Id));

                                Tuple<string, string> hostAndPort = options.DetermineHostDetailsCallback(request);
                                var normalizedRequest = new NormalizedRequest(request, artifacts, hostAndPort.Item1, hostAndPort.Item2);
                                var crypto = new Cryptographer(normalizedRequest, artifacts, credential);

                                // Request body is needed only when payload hash is present in the request
                                string body = null;
                                if (artifacts.PayloadHash != null && artifacts.PayloadHash.Length > 0)
                                {
                                    body = await request.ReadBodyAsStringAsync();
                                }

                                if (crypto.IsSignatureValid(body, request.ContentType)) // MAC and hash checks
                                {
                                    if (IsTimestampFresh(now, artifacts, options))
                                    {
                                        // If you get this far, you are authentic. Welcome and thanks for flying Hawk!

                                        // Before returning the result, store nonce to detect replays.
                                        options.StoreNonceCallback(artifacts.Nonce, credential.Id, options.ClockSkewSeconds);

                                        return new AuthenticationResult()
                                        {
                                            IsAuthentic = true,
                                            Artifacts = artifacts,
                                            Credential = credential,
                                            ApplicationSpecificData = artifacts.ApplicationSpecificData
                                        };
                                    }
                                    else
                                    {
                                        // Authentic but for the timestamp freshness.
                                        // Give a chance to the client to correct the clocks skew.
                                        var timestamp = new NormalizedTimestamp(DateTime.UtcNow, credential, options.LocalTimeOffsetMillis);
                                        request.ChallengeParameter = timestamp.ToWwwAuthenticateHeaderParameter();
                                    }
                                }
                            }
                        }
                        else
                        {
                            HawkEventSource.Log.NonceReplay(artifacts.Nonce, lastUsedBy);
                        }
                    }
                }
            }

            return new AuthenticationResult() { IsAuthentic = false };
        }
Exemplo n.º 7
0
        /// <summary>
        /// Returns an AuthenticationResult object corresponding to the result of authentication done
        /// using the client supplied artifacts in the bewit query string parameter.
        /// </summary>
        /// <param name="bewit">Value of the query string parameter with the name of 'bewit'.</param>
        /// <param name="now">Date and time in UTC to be used as the base for computing bewit life.</param>
        /// <param name="request">Request object.</param>
        /// <param name="options">Hawk authentication options</param>
        internal static AuthenticationResult Authenticate(string bewit, ulong now, IRequestMessage request, Options options)
        {
            if (!String.IsNullOrWhiteSpace(bewit))
            {
                if (request.Method == HttpMethod.Get)
                {
                    if (options != null && options.CredentialsCallback != null)
                    {
                        var parts = bewit.ToUtf8StringFromBase64Url().Split('\\');

                        if (parts.Length == 4)
                        {
                            ulong timestamp = 0;
                            if (UInt64.TryParse(parts[1], out timestamp) && timestamp * 1000 > now)
                            {
                                string id = parts[0];
                                string mac = parts[2];
                                string ext = parts[3];

                                if (!String.IsNullOrWhiteSpace(id) && !String.IsNullOrWhiteSpace(mac))
                                {
                                    RemoveBewitFromUri(request);

                                    Credential credential = options.CredentialsCallback(id);
                                    if (credential != null && credential.IsValid)
                                    {
                                        var artifacts = new ArtifactsContainer()
                                        {
                                            Id = id,
                                            Nonce = String.Empty,
                                            Timestamp = timestamp,
                                            Mac = mac.ToBytesFromBase64(),
                                            ApplicationSpecificData = ext ?? String.Empty
                                        };

                                        var normalizedRequest = new NormalizedRequest(request, artifacts) { IsBewit = true };
                                        var crypto = new Cryptographer(normalizedRequest, artifacts, credential);

                                        if (crypto.IsSignatureValid()) // Bewit is for GET and GET must have no request body
                                        {
                                            return new AuthenticationResult()
                                            {
                                                IsAuthentic = true,
                                                Credential = credential,
                                                Artifacts = artifacts,
                                                ApplicationSpecificData = ext
                                            };
                                        }   
                                    }
                                }
                            }
                        }
                    }
                }
            }

            return new AuthenticationResult() { IsAuthentic = false };
        }