Patent ID: 11880832
Assignee: THALES DIS FRANCE SAS
Field: Digital communication (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 8:
9. A non-transitory memory storing a transaction application for enhancing security of a communication device having at least one processor and one or more memories storing instructions that executable by the at least one processor, when conducting a transaction, defined by transaction data, using the communication device,
the transaction application comprising instructions for causing the processor of the communication device to perform the transaction, the transaction application having a processing unit, the processing unit comprising:
a provisioning service configured to establish a communication with a remote system during a provisioning or replenishment phase of a bound session cryptographic key received from a remote system, wherein the bound session cryptographic key being bound, using a reversible function, to a specific context defined with a binding preventing data related to a transaction wherein said binding of said session cryptographic key to said binding preventing data prevents unauthorized use and/or access of an unbound session cryptographic key so that any change in the specific context corrupts the unbound session cryptographic key during a subsequent unbinding phase, the bound session cryptographic key being encrypted with a transport key, and the transport key being encrypted with a static key;

the transaction application further comprising a controlling unit, the controlling unit comprising a security module;
the processing unit to transmit, to the security module of the controlling unit, the encrypted bound session cryptographic key bound to the specific context;
during computation of a transaction cryptogram, the security module of the transaction application comprising instructions to:
retrieve the static key;
recover the transport key by decrypting the encrypted transport key;
recover the bound session cryptographic key using the recovered transport key;
retrieve a unbinding preventing data and to unbind the bound session cryptographic key from the specific context with the retrieved unbinding preventing data using an inverse function of the reversible function;
compute a cryptogram using a one-way cryptographic hash function to the transaction data from the unbound session cryptographic key, wherein the transaction is authorized based on whether the computed transaction cryptogram is the expected one and the unbinding session cryptographic key is not corrupted.