A method for protection of data includes maintaining a control parameter indicative of a current version of the data. The data is partitioned into multiple segments. Respective signatures of the segments are computed, responsively to the control parameter, the segments and respective signatures forming respective signed input segments, which are stored in a memory. After the signed input segments are stored, a signed output segment is fetched from the memory. The signature of the signed output segment is verified responsively to the control parameter, and the data in the signed output segment is processed responsively to verifying the signature.