Patent ID: 8090951

Claim:
A method for providing secure transmissions across a network comprising a client device and a server, the method comprising: at the client device, generating a stream of watermark bits; generating a plurality of watermarks, each of the plurality of watermarks comprising a respective index number and a respective portion of the stream of watermark bits; inserting the plurality of watermarks into respective headers of a plurality of outgoing packets; receiving, at the server, the plurality of outgoing packets; and determining if a received packet is valid based on the watermark in the header of the received packet; wherein determining if a received packet is valid comprises: comparing the watermark of the received packet to a first and a second window, each of the windows comprising a set of expected watermarks; and accepting the watermark as valid if the received watermark matches one of the expected watermarks in the first or second windows; and wherein comparing the watermark further comprises: maintaining at the server a record of a pivotal index number representing the index number of the highest-numbered valid watermark received from the client device; and comparing the watermark of the received packet to the first and the second window, wherein the first window represents expected watermarks whose index numbers precede the pivotal index number and the second window represents expected watermarks whose index numbers immediately supersede the pivotal index number.