Authenticated Encryption (AE) is a block cipher mode of operation which provides confidentiality and integrity simultaneously. In terms of the hardware implementation, it produces smaller area compared to two separated algorithms. Therefore, it has become popular and a number of modes have been proposed. This paper presents two efficient hardware implementations for AE schemes, AES-GCM and AEGIS. In terms of AES-GCM, the performance of the system is always determined by the Galois Hash (GHASH) architecture because of the inherent computation feedback. This paper introduces an efficient method for implementing the pipelined Karatsuba Ofman Algorithm (KOA)-based GHASH on FPGAs. In particular, the computation feedback is removed by analyzing the complexity of the computation process. In addition, an efficient AEGIS is also implemented using only five AES rounds. The proposed architectures are evaluated with three different implementations of AES SubBytes (BRAMs-based SubBytes, composite field-based SubBytes, and LUT-based SubBytes) to increase the flexibility of the presented work. The presented architectures are implemented using Xilinx Virtex-5 FPGAs. Our comparison to previous work reveals that our architectures are more performance-efficient (Throughput/Slices).