Abstract —Recently, a fast and secure hash function SFHA – 256 has been proposed and claimed as more secure and as having a better performance than the SHA – 256. In this paper an improved version of SFHA – 256 is proposed and analyzed using two parameters, namely the avalanche effect and uniform deviation. The experimental results and further analysis ensures the performance of the newly proposed and improved SFHA-256. From the analysis it can be concluded that the newly proposed algorithm is more secure, efficient, and practical. Keywords —SHA-256, SFHA-256, Improved SFHA-256 1. I NTRODUCTION The hash function H accepts the variable-sized message M as input and outputs a fixed-size representation H(M) of M, which is sometimes called a message digest [1]. I.B. Damgard et.el., discussed the construction of hash functions and presented an efficient and much more secure scheme with the combination of RSA system with the collision free hash function based on fac-toring [2]. Hash functions for message authentications are proposed in [3]. A universal one-way hash function family is discussed in [4]. SHA-1 is a cryptographic hash function published by the National Institute of Standards and Technology (NIST). The three SHA algorithms are SHA-0, SHA-1, and SHA-2. The SHA-0 algorithm was not used in many applications. On the other hand, SHA-2 differs from the SHA-1 hash function. SHA-1 is the most widely used hash function. Several widely-used security ap-plications and protocols are based on SHA-1. In 2005, security flaws were identified in SHA-1 [5]. A prime motivation for the publication of the Secure Hash Algorithm was the Digital Signa-ture Standard. The Digital Signature Algorithm (DSA) is a United States Federal Government standard or FIPS for digital signatures. It was proposed by the National Institute of Standards and Technology (NIST) in August 1991 for use in their Digital Signature Standard (DSS). The ElGamal signature scheme is a digital signature scheme that is based on the difficulty of com-puting discrete logarithms. It was described by Taher ElGamal in 1984 [6]. The Elliptic Curve Digital Signature Algorithm (ECDSA) is a variant of the Digital Signature Algorithm (DSA) that uses Elliptic curve cryptography [7, 8]. Recently, Hassan. M. Elkamchouchi et el., proposed a fast and secure hash function (SFHA -