Methods and systems for encoding and protecting data using digital signature and watermarking techniques

Abstract

Systems and methods are provided for determining a presence of a watermark in electronic data. In certain embodiments, a plurality of keys is generated, and a plurality of payloads are retrieved from electronic data using the keys. A statistical indicia of randomness is generated based on the payloads, and the presence of a watermark is determined when the indicia is below a threshold.

1 - 17 . (canceled) 
     
     
         18 . A computer-implemented method for encoding an electronic file for protection against unauthorized modification, the method comprising:
 identifying a set of mark-holder candidates in the electronic file;   identifying a subset of mark-holder candidates of the set of mark-holder candidates; and   inserting a mark in the subset of mark-holder candidates using a first key.   
     
     
         19 . The method of  claim 18 , wherein the method further comprises discarding the first key. 
     
     
         20 . The method of  claim 18 , wherein the method further comprises storing the first key in a secure storage location. 
     
     
         21 . The method of  claim 18 , wherein inserting the mark in the subset of mark-holder candidates comprises inserting the mark in the subset of mark-holder candidates such that a statistically significant mark hit rate can be obtained regardless of whether an incorrect key is used to retrieve the mark. 
     
     
         22 . The method of  claim 21 , wherein the mark hit rate comprises a number of mark-holder candidates in the subset of mark-holder candidates divided by a total number of mark-holder candidates of the set of mark-holder candidates. 
     
     
         23 . The method of  claim 18 , wherein identifying the subset of mark-holder candidates comprises:
 determining an amount of degradation resulting from insertion of the mark in each mark-holder candidate of the set mark-holder candidates; and   identifying the subset of mark-holder candidates based on the amount of degradation of each mark-holder candidate of the subset of mark-holder candidates being lower than a threshold amount of signal degradation.   
     
     
         24 . The method of  claim 18 , wherein identifying the subset of mark-holder candidates comprises:
 determining a probability of the mark being altered by an attacker after insertion in each mark-holder candidate of the set of mark-holder candidates; and   identifying the subset of mark-holder candidates based on the probability of each mark holder-candidate of the subset of mark-holder candidates being lower than a threshold probability.   
     
     
         25 . The method of  claim 18 , wherein each mark-holder candidate of the subset of mark-holder candidates comprises at least a part of a payload. 
     
     
         26 . The method of  claim 25 , wherein a plurality of mark-holder candidates of the subset of mark-holder candidates comprise a same part of a payload. 
     
     
         27 . The method of  claim 18 , wherein the mark comprises a strong watermark. 
     
     
         28 . A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, are configured to cause the processor to:
 identify a set of mark-holder candidates in the electronic file;   identify a subset of mark-holder candidates of the set of mark-holder candidates; and   insert a mark in the subset of mark-holder candidates using a first key.   
     
     
         29 . The non-transitory computer-readable storage medium of  claim 28 , wherein the instructions are further configured to cause the processor to discard the first key. 
     
     
         30 . The non-transitory computer-readable storage medium of  claim 28 , wherein the instructions are further configured to cause the processor to store the first key in a secure storage location. 
     
     
         31 . The non-transitory computer-readable storage medium of  claim 28 , wherein inserting the mark in the subset of mark-holder candidates comprises inserting the mark in the subset of mark-holder candidates such that a statistically significant mark hit rate can be obtained regardless of whether an incorrect key is used to retrieve the mark. 
     
     
         32 . The non-transitory computer-readable storage medium of  claim 31 , wherein the mark hit rate comprises a number of mark-holder candidates in the subset of mark-holder candidates divided by a total number of mark-holder candidates of the set of mark-holder candidates. 
     
     
         33 . The non-transitory computer-readable storage medium of  claim 28 , wherein identifying the subset of mark-holder candidates comprises:
 determining an amount of degradation resulting from insertion of the mark in each mark-holder candidate of the set mark-holder candidates; and   identifying the subset of mark-holder candidates based on the amount of degradation of each mark-holder candidate of the subset of mark-holder candidates being lower than a threshold amount of signal degradation.   
     
     
         34 . The non-transitory computer-readable storage medium of  claim 28 , wherein identifying the subset of mark-holder candidates comprises:
 determining a probability of the mark being altered by an attacker after insertion in each mark-holder candidate of the set of mark-holder candidates; and   identifying the subset of mark-holder candidates based on the probability of each mark-holder candidate of the subset of mark-holder candidates being lower than a threshold probability.   
     
     
         35 . The non-transitory computer-readable storage medium of  claim 28 , wherein each mark-holder candidate of the subset of mark-holder candidates comprises at least a part of a payload. 
     
     
         36 . The non-transitory computer-readable storage medium of  claim 35 , wherein a plurality of mark-holder candidates of the subset of mark-holder candidates comprise a same part of a payload. 
     
     
         37 . The non-transitory computer-readable storage medium of  claim 28 , wherein the mark comprises a strong watermark.