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    DATA DETERMINATION METHODS, APPARATUSES, STORAGE MEDIA, AND TERMINAL DEVICES
    24.
    发明公开
    DATA DETERMINATION METHODS, APPARATUSES, STORAGE MEDIA, AND TERMINAL DEVICES 审中-公开

    公开(公告)号：EP4262140A1

    公开(公告)日：2023-10-18

    申请号：EP23168142.0

    申请日：2023-04-15

    申请人： Alipay (Hangzhou) Information Technology Co., Ltd.

    发明人： CUI, Jinming ,  ZHOU, Jingren ,  WANG, Li

    IPC分类号： H04L9/08 ,  G06F21/60 ,  G06F21/62 ,  H04L9/40 ,  H04L9/30

    摘要： This specification discloses data determination methods, apparatuses, storage media, and terminal devices. The method includes: A first terminal device sends first encrypted data to a second terminal device; the second terminal device encrypts the first encrypted data by using a second public key to obtain second encrypted data, and sends the second encrypted data and third encrypted data to the first terminal device; the first terminal device encrypts the third encrypted data by using a first public key to obtain fourth encrypted data, acquires first intersection data of the second encrypted data and the fourth encrypted data, and sends the first intersection data to a third terminal device; the third terminal device acquires fifth encrypted data sent by the first terminal device; the third terminal device determines second intersection data based on the fifth encrypted data and the first intersection data, and sends the second intersection data to the first terminal device and the second terminal device.

    METHOD SECURED AGAINST SIDE-CHANNEL ATTACKS PERFORMING A CRYPTOGRAPHIC ALGORITHM COMPRISING A POLYNOMIAL OPERATION
    28.
    发明公开
    METHOD SECURED AGAINST SIDE-CHANNEL ATTACKS PERFORMING A CRYPTOGRAPHIC ALGORITHM COMPRISING A POLYNOMIAL OPERATION 审中-公开

    公开(公告)号：EP4199410A1

    公开(公告)日：2023-06-21

    申请号：EP21306829.9

    申请日：2021-12-17

    申请人： Thales Dis France SAS

    发明人： VIGILANT, David ,  ROUSSELLET, Mylène ,  PERION, Fabrice

    IPC分类号： H04L9/00 ,  H04L9/30

    摘要： The present invention relates to a method secured against side channel attacks performing a cryptographic operation of a cryptographic algorithm, said cryptographic operation comprising at least one polynomial operation on at least one input polynomial A[X] in a first polynomial ring R q = F q [X]/(X n +1), with n an integer and q a first integer being a prime number, wherein said method is performed by a cryptographic device and comprises :
    - selecting a multiplier integer t and determining a second integer q' by multiplying said first integer q by said selected multiplier integer t (S1),
    - for each input polynomial A[X] with coefficients Ai in F q with i in [0,...,n-1],
    ∘ determining (S2) an invertible random polynomial R[X] in said first polynomial ring R q ,
    ∘ randomizing (S3) the coefficients Ai of said input polynomial A[X] based on said determined second integer q' and said determined random polynomial R[X] by:
    ✔ transforming the input polynomial A[X] into a lifted input polynomial A'[X] with coefficients Ai' such that Ai' = Ai + q mod q', with i in [0,...,n-1], the lifted input polynomial A'[X] being a polynomial in a second polynomial ring R q' = F q' [X]/(X n +1),
    ✔ randomizing the lifted input polynomial A'[X] by multiplying it by the random polynomial R[X] modulo said second integer q' to obtain a randomized input polynomial A"[X] in said second polynomial ring R q' ,

    - performing (S4) the at least one polynomial operation of the cryptographic operation on said randomized input polynomials A"[X] instead of said input polynomials A[X] to obtain a result polynomial Res"[X] with coefficients Resi in F q' ,
    - unmasking (S5) the result polynomial Res"(X) by applying to its coefficients a modulo said first integer q operation and/or by multiplying it by inverses of said random polynomials R[X] determined for the input polynomials to provide a result of the cryptographic operation.