This is a work done on cryptography. Conventionally, data is protected from unauthorized interception or eavesdropping by analog techniques. In a digital data security system, when you press a button in the DTMF generator set keypad for data send a connection is made that generates a resultant signal of two tones at the same time. These two tones are taken from a row frequency and a column frequency. The resultant frequency signal is called "Dual Tone Multiple Frequency". These tones are identical and unique. The data signal is converted into binary code, binary form using a DTMF decoder. NOT gate converts into wrong binary form original binary code. In the receiver section, using AND gate and inverter IC for converts the wrong binary code into original binary form help of password circuit. The password circuit is built around dual 4-bit static shift registers and Ex-OR gate. The shift registers store the entered password in binary form. This section actives the converter into original binary form. This circuit shows original and wrong binary form.
It allows people to carryover the confidence found in the physical world to the electronic world, allowing people to do business electronically without worries of deceit and deception. This way data is send from the transmitter in a changed sequence and displays wrong at the receivers end but when a selected password is entered to it then it converts in right information there is no possibility of leakage of private data in medium or at receivers end. Here we share a secret quantity in such a way that a subset of the shares can reconstruct the secret. Govt. has taken an even bigger interest in cryptography due to its use in military. It is useful for secure communication during wartime because the enemy may have access to the communication medium, messages must be encrypted
It includes authentication which is a part of cryptography, it is as fundamentally a part of our lives as privacy, we use authentication in our everyday lives- when we sign our name to some document for instance and as we move to a world where our decisions and agreements are communicated electronically we need to have electronic techniques for providing authentication. After signing documents, agreeing to what is written in document someone can change that document and your signature is still attached?
[...] H Ellis: The Possibility of Secure Non-Secret Digital Encryption, CESG Report, January 1970]) Public key cryptography is an asymmetric scheme that uses a pair of keys for encryption: a public key, which encrypts data, and a corresponding private, or secret key for decryption. You publish your public key to the world while keeping your private key secret. Anyone with a copy of your public key can then encrypt information that only you can read. Even people you have never met. [...]
[...] The data across the outputs of IC-4015, along with the password set by DIP switches, should result into a low output across the output of IC-4072. Once all the four digits of the password are entered, the 4-bit static data is available at the outputs of the shift registers (IC-4015). PASSWORD SETTING EXAMPLE Keypad Decoder output Register output No. Seq. D C B A Password setting (refer table). Suppose you want to set up the password 9765. Press digits 9,7,6 and 5 sequentially and the password gets stored into shift registers IC -4015 in binary format. [...]
[...] You might think of an X.509 certificate as looking like a standard paper certificate (similar to one you might have received for completing a class in basic First Aid) with a public key taped to it. It has your name and some information about you on it, plus the signature of the person who issued it to you. Figure 1-10. An X.509 certificate Probably the most widely visible use of X.509 certificates today is in web browsers. Validity and trust Every user in a public key system is vulnerable to mistaking a phony key (certificate) for a real one. [...]
[...] DIODE The simplest semiconductor device is made up of a sandwich of and N type semi conducting material, with contacts provided to connect the P-and type layers to an external circuit, this is a junction Diode. If the positive terminal of the battery is connected to the p-type material (cathode) and the negative terminal to the N-type material (Anode), a large current will flow. This is called forward current or forward biased. If the connection is reversed, a very little current will flow. [...]
[...] way data is send from the transmitter in a changed sequence and displays wrong at the receivers end but when a selected password is entered to it then it converts in right information there is no possibility of leakage of private data in medium or at receivers end. Here we share a secret quantity in such a way that a subset of the shares can reconstruct the secret. Govt. has taken an even bigger interest in cryptography due to its use in military. [...]
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