Cryptography

1. Cryptography is the science of using mathematics to encrypt and decrypt data.

2. Cryptography enables you to store sensitive information or transmit it across insecure networks (like the Internet) so that it cannot be read by anyone except the intended recipient.

3. While cryptography is the science of securing data, cryptanalysis is the science of analyzing and breaking secure communication (stealing the data).

4. Classical cryptanalysis involves an interesting combination of analytical reasoning, application of mathematical tools, pattern finding, patience, determination, and luck. Cryptanalysts are also called attackers. Cryptology embraces both cryptography and cryptanalysis.

              Plain text         encryption               cipher text              decryption          plaintext(text sent)

                       A related discipline is steganography, which is the science of hiding messages

rather than making them unreadable. (Hiding behind images).

“There are two kinds of cryptography in this world:

cryptography that will stop your kid sister from reading your files

Cryptography that will stop major governments from reading your files”.(you can create your own encryption format).

 Cryptography can be strong or weak.

No one has proven that the strongest encryption obtainable today will hold up under tomorrow’s computing power. However, the strong cryptography employed by PGP is the best available today.( A cryptographic algorithm, plus all possible keys and all the protocols that make it work, comprise a cryptosystem. PGP is a cryptosystem.)

Cryptography can be classified into two types,

Conventional cryptography

Public- key cryptography

Conventional cryptography:

                                          In conventional cryptography, also called secret-key or symmetric-key encryption, one key is used both for encryption and decryption .This can be explained by the diagram as follows, 

Public-key cryptography:

                                                  Public-key cryptography uses a pair of keys: a public key for encrypting data, and a corresponding private key for decryption. Because it uses two keys, it is sometimes called asymmetric cryptography. 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. Only the person who has the corresponding private key can decrypt the information.

Public key                Private key

Hope this tutorial help you to understand the concept of cryptography. In the next tutorial we will give a detailed view about the process of encryption and decryption. Feel free to comment…..