What is Steganography?

Steganography is the science of hiding secret messages inside another larger and harmless-looking message. This technique goes a step beyond regular cryptography, which simply encrypts the message — steganography hides the existence of the message itself.

The hidden message may be embedded in an image, audio, video, or text file, resulting in a cover object that looks normal to the human eye or ear.

Some common terms related to steganography include:

• plaintext: The original secret message to be communicated.
• ciphertext: The encrypted version of the plaintext (optional).
• covertext: Innocent-looking data (image, audio, etc.) used to carry the secret.
• stegotext: The output after embedding the message inside the covertext.

The standard process is to first encrypt the plaintext to form ciphertext (optional but recommended), then embed that ciphertext into the covertext using a steganographic method. The result is the stegotext. On the receiver's end, the hidden data is extracted and decrypted to retrieve the original plaintext.

What is a Digital Signature?

Digital Signature is a cryptographic method used to verify the authenticity and integrity of a message, file, or data. It serves as a digital fingerprint created using a private key and verified with a public key.

In StegoShark, digital signatures are used to:

• Ensure that the hidden content has not been tampered with during transmission.
• Prove that the content was embedded by a legitimate sender.

A digital signature helps ensure non-repudiation: the sender cannot deny having signed the data, and the receiver can confidently verify both the source and the integrity of the information.