Telefonaktiebolaget Lm Ericsson (publ)

Patrik Lantz

Bernard Smeets

Michael Liljenstam

Björn Johansson

An efficient obfuscation of program control flow, comprising obscuring a control execution flow through a plurality of code blocks of a computer program. It involves obtaining a secret key, initializing a state variable based on the secret key, generating a switching value by processing the state variable through an encoding function, and selecting a code block from among a set of code blocks using the switching value. It further involves executing the block code, which comprises updating the state variable based on a present value of the state variable, and repeating the steps of generating a switching value, selecting a code block, and executing the code block to control execution flow through the set of code blocks.

Efficient obfuscation of program control flow

A method to obscure a control execution flow in a computer program includes initializing a state variable, q, and a switching variable, selecting a code block for execution using a present value of the switching variable, executing the code block, updating the state variable based on a present value of the state variable and a block-dependent constant that is associated with the code block to generate an updated state variable, and by applying a state update function to the updated state variable, and updating the switching variable by processing the state variable through a non-injective output function that generates a new value of the switching variable based on the state variable. The operations of selecting the code block, executing the code block, updating the state variable and updating the switching variable are repeated to control execution flow.

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Dalby, Sweden

Patrik Lantz