Abstract: The present invention relates to a method for secure authentication and data exchange, in client server architecture, comprising: registering a user and creating a first tabular data using the user's password for authentication of the user, at a server machine, deleting the password in its original form from the server, said server processing said first tabular data and generating a second tabular data to be sent to the client machine when said user logs in for a transaction at the client machine, said server initialing a communication session with the user using said second tabular data and generating a first set of numbers to be used for decryption by the server, encrypting and transferring said second tabular data to said user at the client machine, said client machine generating a second set of numbers to be used for encryption, using said second tabular data, said client encrypting the plain text using said second set of numbers, in a loop for a predetermined number of iterations, said client transmittin