Thales Dis France Sas

Thales Dis France Sa

Jan Vacek

Aline Gouget

Sylvain Leveque

Michael Adjedj

Michael Gardiner

Stéphane Grellier

Generation of stateful hash based signatures of messages to be signed in a key management system including a plurality of tamper-proof computing devices by a manager device of generating a master merkle tree, triggering generating a predetermined number of slave merkle trees, for each message to be signed selecting a tamper-proof computing device for signing, assigning one yet unassigned generated slave merkle tree to said selected tamper-proof computing device, generating and sending to said selected tamper-proof computing device a command comprising said message to be signed, data enabling to obtain an OTS private key of the assigned slave merkle tree to be used to generate an OTS signature of the message to be signed, and a state value associated to said assigned slave merkle tree and keeping track of the OTS private keys of said assigned slave merkle tree already used for generating a signature.

Method for generating stateful hash based signatures of messages to be signed

Provided is a method for generating a digital signature of an input message (M) based on a secret key (d) of a client device having access to a first set and a second set of precomputed data stored in a storage unit. The first set of precomputed data comprises private element parts (k) protected with an homomorphic encryption. The second set of precomputed data comprises public element parts (Q) paired with the private element parts of the first set. Each private element part is a discrete logarithm of the public element part paired therewith. The private element (k), can be homomorphically encrypted, by combining homomorphically encrypted private element parts selected in the first set (k). The selection of the public and private element parts depends on the input message. Other embodiments are disclosed.

Method for generating a digital signature of an input message

Protection of a data file to be used by a white-box cryptography software application installed in memory of a device to prevent the malevolent use of a digital copy of the data file by a white-box cryptography (WBC) software application installed in memory of another device. The mechanism includes extracting an unique identifier for the device from the environment of the device and modifying data in the data file according to the unique identifier, the available white-box cryptography software application includes a software security layer to retrieve the unique identifier from the environment of the device in which the software application is installed and to use this unique identifier in combination with the stored data file when executing, the result of the execution being correct only in case where the correct unique identifier has been extracted by the executed WBC software application.

Anti cloning for white box protected data

The present invention relates to a method for a secure execution of a whitebox cryptographic algorithm applied to a message (m) and protected by countermeasures based on pseudo-random values, comprising the steps of:

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Meudon, France

Jan Vacek