Cryptography:

1. An original message is known as plain text while the coded message is known as cipher text.

2. The process of converting plain text to cipher text is known as ciphering or encryption, restoring the main text from cipher text is known as deciphering or decryption.

3. The various schemes used for encryption are known as Cryptography and the system is used to known as Cryptographic system.

4. Techniques used for deciphering a message without any knowledge of ciphering details are known as crypto-analysis.

5. The area of cryptography and crypto-analysis together is called as cryptology.

Steganography:

1. The method of cryptogaphy renders the message unintelligible to outsiders by various transformations of the text.

2. The method of steganography conceals the existence of message.

3. The various techniques used are:

i. Character marking: Selected letters are overwritten in pencil. The marks are ordinarily not visible unless the paper is held at an angle to bright light.

ii. Invisible ink: A number of substances can be used for writing but leave no trace until heat or some chemical is applied to the paper.

iii. Pin punctures: Small pin punctures on the pictures are ordinarily not visible unless the paper is held up in front of light.

iv. Subset method: In this method subset of the words of the overall message is used to convey the hidden message.

1. **Disadvantages/ Drawbacks compared to Encryption:

i. It requires a lot of overhead to hide a relatively few bits of information.

ii. Once the system is discovered it becomes totally useless.

1. Alternatively a message can be encrypted and then hidden using steganography.