Encryption & Decryption

Encryption

Encryption  is a  process of coding information which could either be a file or  mail message  in into cipher text  a form unreadable without a decoding key in order to prevent anyone except the intended recipient from reading that data. Decryption is the reverse process of converting encoded data to its original un-encoded form, plaintext.

A key  in cryptography is a long sequence of bits used by encryption / decryption algorithms. For example, the following represents a hypothetical 40-bit key:

00001010 01101001 10011110 00011100 01010101

A given encryption algorithm takes the original message, and a key, and alters the original message mathematically based on the key's bits to create a new encrypted message. Likewise, a decryption algorithm takes an encrypted message and restores it to its original form using one or more keys.

There are two primary approaches to encryption: symmetric and public-key. Symmetric encryption is the most common type of encryption and uses the same key for encoding and decoding data. This key is known as a session key. Public-key encryption uses two different keys, a public key and a private key. One key encodes the message and the other decodes it. The public key is widely distributed while the private key is secret.

Aside from key length and encryption approach, other factors and variables impact the success of a cryptographic system. For example, different cipher modes, in coordination with initialization vectors and salt values, can be used to modify the encryption method. Cipher modes define the method in which data is encrypted. The stream cipher mode encodes data one bit at a time. The block cipher mode encodes data one block at a time.

Advantages of Encryption

-          Confidentiality of information is guaranteed.

-          Provide authentication and integrity protection in the checksum algorithm / hash.

-          Tackling the phone tapping and email

-          For digital signature

Disadvantages of Encryption

-          Encryption terrorist plot.

-          Concealment of crime by a criminal record.

-          Messages can not be read when the recipient forgot or lost the key.

Decryption

Decryption (decryption) is the reverse process, from chiphertext converted back to plaintext by using mathematical functions and key.

Decryption of data and display data retrieved from a database table after

Reversal process data from plaintext to ciphertext can be done by reversing the encryption process. This process is done when the data is retrieved from the database and before the data is displayed / processed, so the data is displayed / processed data that is already in-decrypted (plaintext).