A method and mechanism for generating object signatures within a file system. A file system is configured to generate signatures for objects such as files. The file system periodically scans objects to identify those which require computation of a new signature. Upon identifying such an object, the file system divides the object into partitions. A transient signature value is then generated for each partition of the object and stored. Upon a subsequent access to the object, a determination may be made as to whether or not a valid signature exists for the object. If a valid signature does not exist for the object, a new signature may be generated for the object by using one or more previously stored valid transient signature values which correspond to particular partitions of the object. The transient signature values which are used may serve as a seed for computation of those transient signature values for object partitions which follow the particular partition. Both object signatures and transient signature values may be cached by the file system and returned in response to requests from user space processes.