US 12,219,067 B2
Digital file anti-forgery protection
Eric Decoux, Vevey (CH); Philippe Gillet, Pully (CH); Philippe Thevoz, Penthalaz (CH); and Elisabeth Wallace, Pully (CH)
Assigned to SICPA HOLDING SA, Prilly (CH)
Appl. No. 17/253,490
Filed by SICPA HOLDING SA, Prilly (CH)
PCT Filed Jun. 3, 2019, PCT No. PCT/EP2019/064376
§ 371(c)(1), (2) Date Dec. 17, 2020,
PCT Pub. No. WO2019/243034, PCT Pub. Date Dec. 26, 2019.
Claims priority of application No. 18178628 (EP), filed on Jun. 19, 2018.
Prior Publication US 2021/0203508 A1, Jul. 1, 2021
Int. Cl. H04L 9/00 (2022.01); G06F 16/9035 (2019.01); G06F 16/9038 (2019.01); H04L 9/06 (2006.01); H04L 9/32 (2006.01)
CPC H04L 9/3236 (2013.01) [G06F 16/9035 (2019.01); G06F 16/9038 (2019.01); H04L 9/0643 (2013.01); H04L 9/3247 (2013.01); H04L 9/50 (2022.05)] 14 Claims
OG exemplary drawing
 
1. A method of securing a given original digital file of a batch of a plurality of original digital files against forgery or tampering, each original digital file of the batch containing its own digital data, comprising the steps of:
for each original digital file of the batch, calculating by means of a one-way function an associated digital file signature of its digital data;
calculating a reference aggregated digital signature corresponding to the batch of original digital files from all the digital file signatures of the original digital files of the batch by means of a one-way accumulator of said digital file signatures, and making available to a user the reference aggregated digital signature;
determining a digital file verification key corresponding to the digital file signature of said given original digital file by means of a one-way accumulator of all the other digital file signatures used for calculating the reference aggregated digital signature;
calculating a candidate digital file signature by means of the one-way function based on the digital file signature and the verification key;
determining that the candidate digital file signature matches the reference aggregated digital signature when a one-way accumulator of said candidate digital file signature and corresponding digital file verification key corresponds to the reference aggregated digital signature;
when it is determined that the candidate digital file signature matches the reference aggregated digital signature, verifying that the candidate digital file signature corresponds to that of an original digital file of the batch;
including in the given original digital file a digital representation of a machine readable security marking containing a representation of the digital data of the given original digital file and its corresponding digital file verification key; and
obtaining a marked original digital file of which digital data are secured against forgery or tampering, wherein
the one-way function is a hash function and a digital file signature of an original digital file is a sequence of a given plurality of bits of lower weights selected from the bits of a hash value of the corresponding digital data.