In this paper we report a more secure and efficient encryption algorithm based on the NTRU cryptographic scheme. NTRU is lattice based scheme resistant to quantum computing, hence it falls under the class of post quantum cryptosystems. It is based on shortest vector problem (svp)[9].The main characteristics of the system are low memory and low computational requirements but it provides high level of security. We present modifications in the NTRU scheme for making it more secure and efficient particularly for applications in wireless and constrained devices. In the original scheme, repetitions in the plaintext message lead to repetitions in the cipher text, which is a source of weakness in the system. To overcome this problem each byte of the input has been digested with different operations that produce different encrypted text even for repeated content of the Plain text message. The second modification is enhancing the public key scheme that makes this system more robust. These two modifications in the NTRU scheme makes it secure even for use in the Quantum Computing environment.