Crypto++ (also known as CryptoPP, libcrypto++, and libcryptopp) is a free and open-source C++ class library of cryptographic algorithms and schemes written by Wei Dai.

Furthermore, the library retains a collection of insecure or obsolescent algorithms for backward compatibility and historical value: MD2, MD4, MD5, Panama Hash, DES, ARC4, SEAL 3.0, WAKE, WAKE-OFB, DESX (DES-XEX3), RC2, SAFER, 3-WAY, GOST, SHARK, CAST-128, and Square.

[15] Lawrence Teo's compilation of previous Crypto++ releases dating back to 1995 can be found in the users group archives.

A distinction is made between the library as a compilation (i.e., collection), which is copyrighted by Wei Dai, and the individual files in it, which are public domain.

The library is copyrighted as a compilation in order to place certain disclaimers (regarding warranty, export, and patents) in the license and to keep the attributions and public domain declarations intact when Crypto++ is distributed in source code form.