Crypto++ Library is a free C++ class library of
cryptographic schemes. Other features include:

* pseudo random number generators (PRNG): ANSI X9.17
appendix C, RandomPool
* password based key derivation functions: PBKDF1
and PBKDF2 from PKCS #5, PBKDF from PKCS #12 appendix B
* Shamir's secret sharing scheme and Rabin's information
dispersal algorithm (IDA)
* fast multi-precision integer (bignum) and polynomial operations
* finite field arithmetics, including GF(p) and GF(2^n)
* prime number generation and verification
* useful non-cryptographic algorithms
o DEFLATE (RFC 1951) compression/decompression with gzip
(RFC 1952) and zlib (RFC 1950) format support
o hex, base-32, and base-64 coding/decoding
o 32-bit CRC and Adler32 checksum
* class wrappers for these operating system features (optional):
o high resolution timers on Windows, Unix, and Mac OS
o Berkeley and Windows style sockets
o Windows named pipes
o /dev/random, /dev/urandom, /dev/srandom
o Microsoft's CryptGenRandom on Windows
* A high level interface for most of the above, using a
filter/pipeline metaphor
* benchmarks and validation testing
* x86, x86-64 (x64), MMX, and SSE2 assembly code for the
most commonly used algorithms, with run-time CPU feature
detection and code selection
o supports GCC-style and MSVC-style inline assembly, and MASM for x64
* certain versions are available in FIPS 140-2 validated form