Authenticated requests can be sent without requiring the requests to include or potentially expose secret information used for the authentication process. A client device use a security credential such as a key to sign a request to be sent to a recipient. When the request is received, the recipient determines whether the request was signed using the correct key for the sender. In some embodiments a client token is included with the request that statelessly encodes the key, enabling a recipient capable of decoding the client token to determine the key and compare that key to the signature of the request. The sender can store the secret information in a secure location, such as a browser security module, such that the secret information is not exposed to the browser or script executing on the client device.