What is cryptography?

February 25, 2006


  • Data that can be read and understood without any special measures is called plaintext
  • The method of disguising plaintext in such a way as to hide its substance is called encryption.
  • Encrypting plaintext results in unreadable gibberish called ciphertext.
  • The process of reverting ciphertext to its original plaintext is called decryption.
  • Cryptography is the science of using mathematics to encrypt and decrypt data.
  • cryptanalysis is the science of analyzing and breaking secure communication.
  • Cryptology embraces both cryptography and cryptanalysis.
  • A cryptographic algorithm, or cipher, is a mathematical function used in the encryption and decryption process. A cryptographic algorithm works in combination with a key—a word, number, or phrase—to encrypt the plaintext.
  • A cryptographic algorithm, plus all possible keys and all the protocols that make it work comprise a cryptosystem.
  • conventional cryptography, also called secret-key or symmetric-key encryption, one key is used both for encryption and decryption.
  • 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.
  • PGP is a hybrid cryptosystem. It combines some of the best features of both conventional and public key cryptography.

How PGP works?
When a user encrypts plaintext with PGP,

  1. PGP first compresses the plaintext.
  2. PGP then creates a session key. This key is a random number generated from the random movements of    your mouse and the keystrokes you type.
  3. This session key works with a conventional encryption algorithm to encrypt the plaintext; the result is ciphertext.
  4. Once the data is encrypted, the session key is then encrypted to the recipient’s public key. This public key-encrypted session key is transmitted along with the ciphertext to the recipient.


  5. Decryption works in the reverse. The recipient’s copy of PGP uses his or her private key to recover the temporary session key, which PGP then uses to decrypt the conventionally-encrypted ciphertext.



Keys are stored in encrypted form. PGP stores the keys in two files on your hard disk; one for public keys and one for private keys. These files are called keyrings. ……………..TO BE CONTINUE 😉 



One Response to “What is cryptography?”

  1. Kids And You Says:

    Thanks for sharing this information. Really is pack with new knowledge. Keep them coming.

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