IT430 Fall2010 Assignment NO 2 Solution

What are the steps involved in symmetric cryptography? Also explain key management in conventional cryptography using some example.

A:
Answer
1) Symmetric Cryptography
When one party wishes to communicate secured data with another and they both share
the same key for encrypting and decrypting the data, the process is known as symmetric
Cryptography.
The shared key is referred to as a symmetric key.
Because the same key is used to encrypt and decrypt the data with symmetric
cryptography, the decryption process is essentially a reversal of the encryption process.
STEPS INVOLVED IN SYMMETRIC CRYPTOGRAPHY:
Symmetric encryption involves the following steps:
1. The sender creates an encoded text message by encrypting the plaintext message
with a symmetric encryption algorithm and a shared key.
2. The sender sends the encoded text message to the recipient.
3. The recipient decrypts the encoded text message back into plaintext with a shared
key.
2) Conventional cryptography
In conventional cryptography, (also called secret-key or symmetric-key encryption),
one key is used both for encryption and decryption.

Key management in conventional cryptography:

Conventional encryption is very fast. It is especially useful for encrypting data that is not going anywhere. However, conventional encryption alone as a means for transmitting secure data can be quite expensive simply due to the difficulty of secure key distribution.
The expense of secure channels and key distribution relegated its use only to those who could afford it, such as governments and large banks.
EXAMPLES:
Following are the examples of key management in conventional cryptography
1-The Data Encryption Standard (DES): is an example of a conventional crypto system that is widely employed by the Federal Government.

2-Captain Midnight's Secret Decoder Ring: (which is an "encoder" ring as well) is also an example of conventional cryptography which allows you to do a simple substitution encryption. It usually has two concentric wheels of letters, A through Z.

3-Julius Caesar's cipher : The Caesar cipher is named for Julius Caesar who used an alphabet with a left shift of three is also an example of conventional cryptography.