weidai11/cryptopp — reverse-engineered prompt

Build me a free C++ cryptography library that developers can drop into their own apps. I want it to handle common security jobs like encrypting and decrypting data, hashing passwords or files, creating secure random keys, signing and verifying messages, and doing key exchange.

Please include well known options like AES, ChaCha20 Poly1305, RSA, DSA, elliptic curve signing and key exchange, SHA 2, SHA 3, HMAC, PBKDF2, HKDF, Scrypt, Base64, Hex, CRC, gzip and zlib support. Make the API feel practical, with simple examples for encrypting a file, hashing a string, making keys, and verifying a signature.

It should build on Windows, macOS, and Linux with normal C++ compilers, include validation tests, benchmarks, and clear build instructions. Add warnings in the docs about older unsafe algorithms that are only kept for compatibility. Look up current docs online if you need to.