Data acquired, for example by a mobile platform, such as a sequence of images observed by a mobile platform, is grouped. A signature is computed for each group and is transmitted along with frame data to a reception system, which verifies correct transmission based on the group signature. The signature may be a root value of a hash tree that has at least selected ones of each group as inputs. Transmission events may also be separately signed as a whole using an event validation system. Although the signature maybe computed for all frames in a group, it may also be computed based on only a subset, selected pseudo-randomly.