Cryptography Vs Steganography

Padding byte stuffing: A technique to hide data in MP3

Abstract: In today’s world, secrecy is of utmost importance in almost all fields. When one needs to share some sensitive information in public networks, it becomes important that information does not go into wrong hands. Here, information security plays a major role. Sensitive information communication can be secured by using either cryptography or steganography. Steganography is a secret communication method for hiding data in some digital media such as images, audio etc. Hiding secret data using audio files as carrier is known as “Audio Steganography”. Moreover, MP3 files being more popular can be good message carriers. With the advancement in digital audio media, many audio steganography

It is the technique to hide secret message inside a carrier file and is later extracted by its intended receiver. Steganography takes cryptography a step further by hiding an encrypted message so that no one suspects it exists. So any intruder scanning the files in ideal condition can never know about existence of the message. As nobody except the sender and the receiver knows the existence of the message, it does not attract unwanted attention. Information security has two techniques: cryptography and steganography. Difference between these two comes from the fact that cryptography is the study of hiding information, while steganography deals with composing hidden messages. Cryptographic methods try to protect the content of a message, while Steganography uses methods that would hide both the message as well as the

These frames consist of a frame header and data block. Frame header contains information about various properties of particular frame such as bitrate, padding bits, CRC etc. Frame header consists of a sync word which indicated the beginning of a frame. Data block of frame contains audio information in terms of frequency and amplitude. MP3 file structure can be better describe with below figure.

MP3 also consist of tags, which contains metadata about the file such as artist name, genre, track length etc. These tags are of two types; ID3V1 and ID3V2. There is no such standardized format defined for tags. ID3V1 tags are appended at the end of file, whereas ID3V2 tags are appended at the start, so navigation is easy. Header of each MP3 frame contains information about frame. So, to know about a frame, we need to locate the frame, an read its header. A frame header is of 4 bytes or 32 bits in length. If we need to represent header in form of characters with each character representing different characterstic of frame, a header can be represented as :

AAAAAAAA AAABBCCD EEEEFFGH IIJJKLMN

Details of these representations are as follows:

Sign Length Description

A 11 Frame