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An absolute security system with a password for sending secret data files

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  1. Introduction
  2. Construction and working
  3. Circuit description
  4. Power supply
  5. Circuit and block diagram
  6. Components
  7. Applications
  8. Advantages and disadvantages
  9. Soldering techniques
  10. Precautions
  11. Bibliography

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. [...]

[...] (The certificate can still be safely used to reconfirm information that was encrypted or signed within the validity period it should not be trusted for cryptographic tasks moving forward, however.) There are also situations where it is necessary to invalidate a certificate prior to its expiration date, such as when an the certificate holder terminates employment with the company or suspects that the certificate's corresponding private key has been compromised. This is called revocation. A revoked certificate is much more suspect than an expired certificate. [...]

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