I've been looking for a fast, powerful and robust algorithm for encrypting large files with authentication . I would like to implement the algorithm on my own without using third party software. I've used different modes of AES but the software implementation is prone to side channel attacks. Besides the most commonly used AES 256 GCM has an encryption with authentication size limit of 64 GB. I've tried other famous ciphers like Xchacha20/ XSalsa20 with poly1305, but I cant get around their respective size limits (I can only encrypt upto 256 GB with XChaCha20 - Poly1305 - IETF version ) !
Is there a powerful enough cipher other than the above that I can use for large scale encryption with authentication ?
What modifications should I apply to existing algorithms like Xchacha20 / XSalsa20 with Poly1305 for unlimited encryption with authentication?