Crypto++

Being a C++ class library of cryptographic schemes, Crypto++ packs a multitude of algorithms you could turn to in order to handle your tasks.
As such, it should be pointed out that among the functionality Crypto ++ provides you with are the following goodies: high-speed stream ciphers such as Panama, Sosemanuk, or ChaCha, as well as authenticated encryption schemes, with EAX, CCM, and GCM being on the list.
Aside from that, public-key cryptography is supported, with DSA and RSA being just two examples in this regard. And this we have touched upon the subject, we should also mention that padding schemes for public-key systems are also included on Crypto++’s list of features.
Moreover, it should be pointed out that key agreement schemes such as Diffie-Hellman (DH), Menezes-Qu-Vanstone (MQV), Fully Hashed MQV (FHMQV), and more can be used.
As for AES and AES candidates, your options include AES (Rijndael), MARS, Twofish, CAST-256, Serpent, and RC6. You might also be interested to know that as far as block ciphers are concerned, you can choose from the following: IDEA, Triple-DES, ARIA, SEED, and more.
In case you intend to focus on elliptic curve cryptography, Crypto++ should provide you with invaluable help, with support for ECNR, ECMQV, ECDSA, ECIES, and more being guaranteed.