remove all external crypto libraries

README.md

@@ -25,10 +25,11 @@ Current version can be viewed with: `./otp --help` or by running the interactive
 ### Prerequisites
 
 - GCC compiler
-- OpenSSL development libraries (`libssl-dev` on Ubuntu/Debian)
 - Git (for version tracking)
 - Make
 
+**Note: OpenSSL is no longer required! This implementation is now completely self-contained.**
+
 ### Build Commands
 
 Use the included build script for automatic versioning:
@@ -125,10 +126,11 @@ These files are excluded from git (.gitignore) and regenerated on each build.
 ## Security Features
 
 - Uses `/dev/urandom` for cryptographically secure random number generation
-- Optional keyboard entropy mixing using HKDF (Hash-based Key Derivation Function)
-- SHA-256 pad integrity verification
+- Optional keyboard entropy mixing using simple XOR operations
+- Custom 256-bit XOR checksum for pad identification (encrypted with pad data)
 - Read-only pad files to prevent accidental modification
 - State tracking to prevent pad reuse
+- **Zero external crypto dependencies** - completely self-contained implementation
 
 ## File Structure