/// <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 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 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
Tuple <string, string> hostAndPort = options.DetermineHostDetailsCallback(request);
var normalizedRequest = new NormalizedRequest(request, this.result.Artifacts, hostAndPort.Item1, hostAndPort.Item2)
{
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 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, options.HostNameSource);
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 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 };
}
/// <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 };
}
/// <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
});
}
/// <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
});
}