This book presented here should be of interest to others studying secured communications over the network. Linear Feedback Shift Register (LFSR) counter is very effective when compared to other counters used in cryptographic applications especially in terms of Hardware, speed of operation and it is also less prone to Glitches.The topic - Data security using Linear Feedback Shift Register is based on hardware experiments in six broad sections. Main Highlights:: Section 1: Describes the brief history of secured communication. Section 2: Describes concept of cryptography, key, classification and Caesar's cipher. It also features a brief idea about security mechanism. Section 3: Describes detailed view of working principle, classification and application of Linear Feedback Shift Register. It also features the study of pseudo random number generation using LFSR. Section 4: Describes the data security and encryption technique using LFSR. Section 5: Portray the implementation of security measures using LFSR. Section 6: Describes the advantages, disadvantages and future scope of data security.