Systems, methods and computer readable media for secure patch downloading from a host to a target, with improved security computation operations based on transport conditions. The method may include receiving a packet of the patch from the host; verifying that the packet is not a retransmission of a previously received packet; if the verification succeeds, performing a first type of security computation based on the packet; if the verification fails and the content of the packet differs from the content of the previously received packet, stopping further performance of the first type of security computation until a final packet of the patch is received; performing a second type of security computation based on one or more of the received packets; and determining a security status of the patch based on a comparison of the first type of security computation and the second type of security computation.