# Server Side Response Validation TruecallerSDK provides two optional delegate methods to check the authenticity of the profile you receive. Note that TruecallerSDK readily offers a simplified way to request and receive a user profile via required delegate methods and verifies the content before forwarding it your app. **Server side Truecaller Profile authenticity check** The delegate method didReceiveTrueProfileResponse: will return a TCTrueProfileResponse instance. Inside TCTrueProfileResponse class there are 3 important fields, payload, signature and signatureAlgorithm. Payload is a Base64 encoding of the json object containing all profile info of the user. Signature contains the payload's signature. You can forward these fields along with the signing algorithm back to your backend and verify the authenticity of the information by doing the following: 1. Fetch Truecaller public keys using this api: (we recommend you cache these keys for future use and refresh the cache only if you cannot verify the signature); 2. Loop through the public keys and try to verify the signature and payload**.** **Request-Response correlation check** Every request created with TruecallerSDK has a unique identifier namely 'requestNonce'. This identifier is bundled into the response for assuring a correlation between a request and a response. If you want you can check this correlation yourself by: 1. Get the request nonce at willRequestProfileWithNonce: method 2. In didReceiveTrueProfileResponse: verify that the previously retrieved identifier matches the one in TCTrueProfileResponse.requestNonce. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.truecaller.com/truecaller-sdk/ios/server-side-response-validation.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.