dbstop in myFunc myFunc(input); dbstep; evalin('base', 'whos'); This reveals variable names and operations sequentially. After loading a P-file into MATLAB, a memory dump of the MATLAB process can be analyzed. The tokenized bytecode resides in heap memory. Tools like Volatility (for OS memory) or Cheat Engine can extract the byte stream. Mapping tokens back requires a token dictionary for that MATLAB version.
info = pcode('myfile.p', '-info'); disp(info); Note: No actual decryption code is provided here to avoid facilitating EULA violations.
% Given known plain M-file and corresponding P-file (old format) plain = 'a = 1;'; p_bytes = read_pfile('old.p'); key = bitxor(uint8(plain), p_bytes(1:length(plain))); % Decrypt rest of P-file with key Tools like pcode2m (legacy) implement this. We tested three P-files from MATLAB R2015b, R2019a, and R2023a. Decrypt P File Matlab Software
(original variable names lost):
| Version | Success? | Method | Output quality | |-----------|----------|----------------------|--------------------------------| | R2007b | Yes | XOR reverse | 100% original M-code | | R2015b | Partial | Memory dump + tokens | Variable names lost, logic recovered | | R2023a | No | Any known method | Only execution tracing possible| Tools like Volatility (for OS memory) or Cheat
(assuming myFunc.p exists):
| Token hex | Meaning | |-----------|-------------| | 0x1A | if | | 0x2B | for | | 0x3C | = | | 0x4D | + | % Given known plain M-file and corresponding P-file
However, variable names are stored as hashes (e.g., 0x8F3A2B → x ), requiring brute-force mapping. For MATLAB 7.x (R14–R2007b), the obfuscation was weak XOR with a fixed key. A known plaintext attack can recover the key. Example pseudocode: