Add XKCP (#156)

README.md

@@ -175,6 +175,7 @@ A curated list of cryptography resources and links.
 - [themis](https://github.com/cossacklabs/themis) - High level crypto library for storing data (AES), secure messaging (ECC + ECDSA / RSA + PSS + PKCS#7) and session-oriented, forward secrecy data exchange (ECDH key agreement, ECC & AES encryption). Ported on many languages and platforms, suitable for client-server infastructures.
 - [tiny-AES128-C](https://github.com/kokke/tiny-AES128-C) - Small portable AES128 in C.
 - [wolfSSL](https://github.com/wolfSSL/wolfssl) - Small, fast, portable implementation of TLS/SSL for embedded devices to the cloud.
+- [XKCP](https://github.com/XKCP/XKCP) — is a repository that gathers different free and open-source implementations of the cryptographic schemes defined by the Keccak team.
 - [xxHash](https://github.com/Cyan4973/xxHash) - Extremely fast hash algorithm.
 
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