Steganography and Cipher: Key Terms You Need To Know

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What is Steganography?

Steganography is concealing or hiding information within other seemingly innocuous data or media, such as images, audio files, text documents, or video files. The term “steganography” is derived from the Greek words “steganos,” meaning “covered,” and “graphia,” meaning “writing.”

Unlike cryptography, which focuses on encrypting data to make it unreadable, steganography aims to make the existence of the hidden information undetectable to an observer. The goal is to ensure that any interception or analysis of the carrier data does not raise suspicion that hidden content is present.

Various techniques can be used to achieve steganography. One common method is to embed the secret information within the least significant bits of the pixels in an image or the samples in an audio file, as these changes are often imperceptible to the human eye or ear. Other techniques involve modifying whitespace in text documents or altering the timing of video frames.

Steganography has both legitimate and malicious applications. It can be used in legitimate contexts for secure communication, copyright protection, or digital watermarking. However, it can also be misused for illicit purposes, such as hiding malicious code or secret messages in media files for covert operations or cyberattacks.

To extract the hidden information from a steganographic file, the recipient must possess the appropriate knowledge or software to reverse the embedding process and reveal the concealed content.

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What is a Cipher?

A cipher, or “cypher,” refers to a method or technique used to encrypt or encode information. It transforms plain, readable text (plaintext) into unintelligible or unreadable form (ciphertext) using various algorithms or mathematical operations. Ciphers are typically employed to ensure the confidentiality and security of sensitive data during transmission or storage.

Ciphers have a long history and have been used for centuries to protect secrets and transmit messages securely. They play a crucial role in cryptography, the study of secure communication and encryption. Ciphers can be classified into several types, including substitution ciphers, transposition ciphers, symmetric-key ciphers, and asymmetric-key ciphers.

Substitution cipher

A substitution cipher replaces each letter or character in the plaintext with another letter or character according to a predetermined rule or mapping. Examples of substitution ciphers include the Caesar cipher, where each letter is shifted to a certain number of positions in the alphabet, and the Atbash cipher, where each letter is replaced with its mirror image.

Transposition ciphers

On the other hand, Transposition ciphers rearrange the order of the letters in plaintext without changing the actual letters themselves. The Rail Fence cipher and the Columnar Transposition cipher are examples of transposition ciphers.

Symmetric-key ciphers,

Symmetric-key ciphers, also known as secret-key ciphers, use the same key for encryption and decryption. The key is kept secret and known only to the sender and receiver. Examples of symmetric-key ciphers include the Data Encryption Standard (DES) and the Advanced Encryption Standard (AES).

Asymmetric-key ciphers

Asymmetric-key ciphers, or public-key ciphers, use a pair of mathematically related keys: a public key for encryption and a private key for decryption. The public key can be freely shared with others, while the private key is kept secret. The RSA algorithm is a well-known example of an asymmetric-key cipher.

Modern ciphers often combine various techniques to provide stronger security and resist attacks. They are essential to secure communication, ensuring that sensitive information remains confidential and protected from unauthorized access.