Procedural code generation for challenge code

A computing device configured to obfuscate challenge code, the computing device comprising:

• one or more processors;
• and
• a non-transitory machine-readable storage medium having instructions stored therein, which when executed by the one or more processors, causes the computing device to:
• obtain challenge code for interrogating a client;
• insert, in the challenge code, code for obfuscating outputs that are to be generated by the client, wherein the code for obfuscating the outputs includes code for applying a first chain of reversible transformations on the outputs using client-generated random values;
• intern strings appearing in the challenge code with obfuscated strings;
• insert code for deobfuscating the obfuscated strings into the challenge code;
• inline function calls in the challenge code;
• remove function definitions that are unused in the challenge code due to the inlining;
• reorder the challenge code without changing the functionality of the challenge code;
• and
• provide the challenge code for execution by the client.

A non-transitory machine-readable storage medium that provides instructions that, if executed by a processor of a computing device, will cause said computing device to perform operations for obfuscating challenge code, the operations comprising:

• obtaining challenge code for interrogating a client;
• inserting, in the challenge code, code for obfuscating outputs that are to be generated by the client, wherein the code for obfuscating the outputs includes code for applying a first chain of reversible transformations on the outputs using client-generated random values;
• interning strings appearing in the challenge code with obfuscated strings;
• inserting code for deobfuscating the obfuscated strings into the challenge code;
• inlining function calls in the challenge code;
• removing function definitions that are unused in the challenge code due to the inlining;
• reordering the challenge code without changing the functionality of the challenge code;
• and
• providing the challenge code for execution by the client.