Both iOS and Android applications can access the Approov SDK enabled API by using the static methods defined in the ApproovService class. This document provides a reference for all of the static methods defined in ApproovService. These are available if you import:
using Approov;Various methods may throw an ApproovException if there is a problem. The property Message provides a descriptive message.
If a method throws an NetworkingErrorException (a subclass of ApproovException) then this indicates the problem was caused by a networking issue, and a user initiated retry should be allowed.
If a method throws an RejectionException (a subclass of ApproovException) the this indicates the problem was that the app failed attestation. An additional property, ARC, provides the Attestation Response Code, which could be provided to the user for communication with your app support to determine the reason for failure, without this being revealed to the end user. The property RejectionReasons provides the Rejection Reasons if the feature is enabled, providing a comma separated list of reasons why the app attestation was rejected.
The ApproovService class implements platform specific code only usable in projects targetting either or both iOS and Android. It is possible to use a Xamarin Forms app to provide UI and application logic but ultimately, the ApproovService needs to access platform specific code which is only available in Android and iOS.
Initializes the Approov SDK and thus enables the Approov features. The config will have been provided in the initial onboarding or email or can be obtained using the approov CLI. This will generate an error if a second attempt is made at initialization with a different config.
void ApproovService.Initialize(string config)It is possible to pass an empty config string to indicate that no initialization is required. Only do this if you are also using a different Approov quickstart in your app (which will use the same underlying Approov SDK) and this will have been initialized first.
The preffered way to obtain an Approov enabled HttpClient, for both iOS and Android, is by using:
ApproovService ApproovService.CreateHttpClient()If you prefer providing your own message handler, you can invoke:
ApproovService ApproovService.CreateHttpClient(HttpMessageHandler handler)If the provided proceed value is true then this indicates that the network interceptor should proceed anyway if it is not possible to obtain an Approov token due to a networking failure. If this is called then the backend API can receive calls without the expected Approov token header being added, or without header/query parameter substitutions being made. This should only ever be used if there is some particular reason, perhaps due to local network conditions, that you believe that traffic to the Approov cloud service will be particularly problematic.
void ApproovService.SetProceedOnNetworkFailure(bool proceed)Note that this should be used with CAUTION because it may allow a connection to be established before any dynamic pins have been received via Approov, thus potentially opening the channel to a MitM.
Sets a development key in order to force an app to be passed. This can be used if the app has to be resigned in a test environment and would thus fail attestation otherwise.
void ApproovService.SetDevKey(string devKey)Sets the header that the Approov token is added on, as well as an optional prefix String (such as "Bearer "). Set prefix to the empty string if it is not required. By default the token is provided on Approov-Token with no prefix.
void ApproovService.SetTokenHeaderAndPrefix(string header, string prefix)Sets a binding header that may be present on requests being made. This is for the token binding feature. A header should be chosen whose value is unchanging for most requests (such as an Authorization header). If the header is present, then a hash of the header value is included in the issued Approov tokens to bind them to the value. This may then be verified by the backend API integration.
void ApproovService.SetBindingHeader(string header)Adds the name of a header which should be subject to secure strings substitution. This means that if the header is present then the value will be used as a key to look up a secure string value which will be substituted into the header value instead. This allows easy migration to the use of secure strings. A requiredPrefix may be specified to deal with cases such as the use of "Bearer " prefixed before values in an authorization header. Set requiredPrefix to null if it is not required.
void ApproovService.AddSubstitutionHeader(string header, string requiredPrefix)Removes a header previously added using addSubstitutionHeader.
void ApproovService.RemoveSubstitutionHeader(string header)Adds a key name for a query parameter that should be subject to secure strings substitution. This means that if the query parameter is present in a URL then the value will be used as a key to look up a secure string value which will be substituted as the query parameter value instead. This allows easy migration to the use of secure strings.
void ApproovService.AddSubstitutionQueryParam(string key)Removes a query parameter key name previously added using addSubstitutionQueryParam.
void ApproovService.RemoveSubstitutionQueryParam(string key)Adds an exclusion URL regular expression via the urlRegex parameter. If a URL for a request matches this regular expression then it will not be subject to any Approov protection.
void ApproovService.AddExclusionURLRegex(string urlRegex)Note that this facility must be used with EXTREME CAUTION due to the impact of dynamic pinning. Pinning may be applied to all domains added using Approov, and updates to the pins are received when an Approov fetch is performed. If you exclude some URLs on domains that are protected with Approov, then these will be protected with Approov pins but without a path to update the pins until a URL is used that is not excluded. Thus you are responsible for ensuring that there is always a possibility of calling a non-excluded URL, or you should make an explicit call to fetchToken if there are persistent pinning failures. Conversely, use of those option may allow a connection to be established before any dynamic pins have been received via Approov, thus potentially opening the channel to a MitM.
Removes an exclusion URL regular expression (urlRegex) previously added using addExclusionURLRegex.
void ApproovService.RemoveExclusionURLRegex(string urlRegex)Performs a fetch to lower the effective latency of a subsequent token fetch or secure string fetch by starting the operation earlier so the subsequent fetch may be able to use cached data. This initiates the prefetch in a background thread.
void ApproovService.Prefetch()Performs a precheck to determine if the app will pass attestation. This requires secure strings to be enabled for the account, although no strings need to be set up.
void ApproovService.Precheck() throws ApproovExceptionThis throws ApproovException if the precheck failed. This will likely require network access so may take some time to complete, and should not be called from the UI thread.
Gets the device ID used by Approov to identify the particular device that the SDK is running on. Note that different Approov apps on the same device will return a different ID. Moreover, the ID may be changed by an uninstall and reinstall of the app.
string ApproovService.GetDeviceID()Directly sets the token binding hash to be included in subsequently fetched Approov tokens. If the hash is different from any previously set value then this will cause the next token fetch operation to fetch a new token with the correct payload data hash. The hash appears in the pay claim of the Approov token as a base64 encoded string of the SHA256 hash of the data. Note that the data is hashed locally and never sent to the Approov cloud service. This is an alternative to using setBindingHeader and you should not use both methods at the same time.
void ApproovService.SetDataHashInToken(string data)Performs an Approov token fetch for the given url. This should be used in situations where it is not possible to use the networking interception to add the token. Note that the returned token should NEVER be cached by your app, you should call this function when it is needed.
string ApproovService.FetchToken(string url) throws ApproovExceptionThis throws ApproovException if there was a problem obtaining an Approov token. This may require network access so may take some time to complete, and should not be called from the UI thread.
Gets the message signature for the given message. This is returned as a base64 encoded signature. This feature uses an account specific message signing key that is transmitted to the SDK after a successful fetch if the facility is enabled for the account. Note that if the attestation failed then the signing key provided is actually random so that the signature will be incorrect. An Approov token should always be included in the message being signed and sent alongside this signature to prevent replay attacks.
string ApproovService.GetMessageSignature(string url) throws ApproovExceptionThis throws ApproovException if there was a problem obtaining a signature.
Fetches a secure string with the given key if newDef is null. Returns null if the key secure string is not defined. If newDef is not null then a secure string for the particular app instance may be defined. In this case the new value is returned as the secure string. Use of an empty string for newDef removes the string entry. Note that the returned string should NEVER be cached by your app, you should call this function when it is needed.
string ApproovService.FetchSecureString(string key, string newDef) throws ApproovExceptionThis throws ApproovException if there was a problem obtaining the secure string. This may require network access so may take some time to complete, and should not be called from the UI thread.
Fetches a custom JWT with the given marshaled JSON payload.
string ApproovService.FetchCustomJWT(string payload) throws ApproovExceptionThis throws ApproovException if there was a problem obtaining the custom JWT. This may require network access so may take some time to complete, and should not be called from the UI thread.