• Script text is encrypted with RC4 (classic + native) or RC4 + AES-256-GCM (native with --aes)
• Encrypted data is embedded in random order with random padding (classic mode)
• Binary payload format does not expose plaintext (native mode)

• Integrity test strings are randomized per build (prevents known-plaintext attacks on RC4)
• Error messages in the runner are XOR-obfuscated (not visible via strings)
• AES-256-GCM provides authenticated encryption with tamper detection

• Anti-ptrace detection (PTRACE_TRACEME on Linux, PT_DENY_ATTACH on macOS)
• /proc/self/status TracerPid monitoring (Linux)
• Environment variable injection detection (LD_PRELOAD, LD_AUDIT, DYLD_INSERT_LIBRARIES, etc.)
• Timer-based anti-debug (detects single-stepping)
• Core dump prevention (RLIMIT_CORE=0, PR_SET_DUMPABLE=0)

• SHA-256 integrity hash of the runner binary, verified at startup
• AES-256-GCM provides ciphertext authentication (any modification detected)

• Password protection with Argon2id (memory-hard, GPU-resistant)
• Expiration dates
• Execution count limits with file locking

• Stdin mode (--stdin-mode) hides script from /proc/*/cmdline
• 4096-space prefix hides script in process listings (default mode)

• All sensitive data (keys, decrypted script, passwords) is zeroed with zeroize after use

A sufficiently motivated attacker with full access to the binary can recover the script. rshc is an obfuscation tool, not a DRM system. Specifically:

• Memory dumping: The decrypted script exists in RAM during execution. Tools like gdb, Frida, or /proc/*/mem can read it.
• Kernel-level tracing: eBPF, strace (with modifications), or kernel modules can intercept the execvp call and capture the script.
• Binary patching: Anti-debug checks can be NOPped out in the binary.
• Brute-force on RC4: RC4 alone is not cryptographically strong. The --aes flag adds proper authenticated encryption.

• The rshc-runner binary is verified not to be a symlink, but no cryptographic signature verification is performed.
• Crypto dependencies are pinned to exact versions. Non-crypto dependencies use semver ranges.

• No protection against timing attacks on the decryption itself.
• The .runs counter file is visible on the filesystem.

• --bind-host and -p (password) cannot be used together (enforced by clap). This is because both features use the same payload field. Use --bind-host OR -p, not both.
• --no-network requires Linux with unshare(CLONE_NEWNET) capability. Fails in some containers or restricted environments.
• -U (untraceable) may cause false positives in CI environments that set ASAN_OPTIONS, LSAN_OPTIONS, or similar sanitizer variables — these are treated as injection attempts.
• seccomp-BPF filtering is NOT implemented. The runner sets PR_SET_NO_NEW_PRIVS (prevents setuid escalation) but does not install a syscall filter. The C runtime's -H flag provides full seccomp-BPF in classic mode.
• mlock() may fail silently if the process has insufficient RLIMIT_MEMLOCK. Sensitive data may still be swapped to disk in constrained environments.

If you discover a security vulnerability, please open an issue at https://github.com/maxgfr/rshc/issues with the label security.