For electronic commerce and other applications it is required to encrypt data that is transmitted over an unsecured channel. The data is encrypted/randomized using a key. Algorithms such as DES and ECC randomize the data such that un-authorized user cannot decrypt it .This thesis presents a practical implementation of a quasi group based multilevel, indexed scrambling transformation for use in signal encryption. Results of experiments with text and speech scrambling are presented. It is shown

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... at the quasi group transformation maximizes the entropy at the output, which is desirable for a good system. This system provides extremely large group of keys that ensures enhanced security. It can work in either the chain mode or the block mode. Block mode is more tolerant to errors compared to the chain mode.