Introduction about Cryptography & Steganography
Cryptography
It is a method of protecting information and communications through the use of codes so that only those for whom the information is intended can read and process it. The prefix “crypt-” means “hidden” or “vault” — and the suffix “-graphy” stands for “writing.”
In computer science, cryptography refers to secure information and communication techniques derived from mathematical concepts and a set of rule-based calculations called algorithms, to transform messages in ways that are hard to decipher. These deterministic algorithms are used for cryptographic key generation, digital signing, verification to protect data privacy, web browsing on the internet, and confidential communications such as credit card transactions and email.
Hashing
It is generating a value or values from a string of text using a mathematical function.
Hashing is one way to enable security during the process of message transmission when the message is intended for a particular recipient only. A formula generates the hash, which helps to protect the security of the transmission against tampering.
Hashing is also a method of sorting key values in a database table in an efficient manner.
When a user sends a secure message, a hash of the intended message is generated and encrypted, and is sent along with the message. When the message is received, the receiver decrypts the hash as well as the message. Then, the receiver creates another hash from the message. If the two hashes are identical when compared, then a secure transmission has occurred. This hashing process ensures that the message is not altered by an unauthorized end user.
Hashing is used to index and retrieve items in a database because it is easier to find the item using the shortened hashed key than using the original value.
Steganography
Steganography is the practice of sending data in a concealed format so the very fact of sending the data is disguised. The word steganography is a combination of the Greek words στεγανός (steganos), meaning “covered, concealed, or protected”, and γράφειν (graphein) meaning “writing”.
Unlike cryptography, which conceals the contents of a secret message, steganography conceals the very fact that a message is communicated. The concept of steganography was first introduced in 1499, but the idea itself has existed since ancient times. There are stories of a method being used in the Roman Empire whereby a slave chosen to convey a secret message had his scalp shaved clean and a message was tattooed onto the skin. When the messenger’s hair grew back, he was dispatched on his mission. The receiver shaved the messenger’s scalp again and read the message.
Cryptography Benefits
Cryptography is an essential information security tool. It provides the four most basic services of information security −
- Confidentiality − Encryption technique can guard the information and communication from unauthorized revelation and access to information.
- Authentication − The cryptographic techniques such as MAC and digital signatures can protect information against spoofing and forgeries.
- Data Integrity − The cryptographic hash functions are playing a vital role in assuring users about data integrity.
- Non-repudiation − The digital signature provides the non-repudiation service to guard against the dispute that may arise due to denial of passing message by the sender.
All these fundamental services offered by cryptography have enabled the conduct of business over the networks using the computer systems in an extremely efficient and effective manner.
Hashing Benefits
One main use of hashing is to compare two files for equality. Without opening two document files to compare them word-for-word, the calculated hash values of these files will allow the owner to know immediately if they are different.
Hashing is also used to verify the integrity of a file after it has been transferred from one place to another, typically in a file backup program like SyncBack. To ensure the transferred file is not corrupted, a user can compare the hash value of both files. If they are the same, then the transferred file is an identical copy.
In some situations, an encrypted file may be designed to never change the file size nor the last modification date and time (for example, virtual drive container files). In such cases, it would be impossible to tell at a glance if two similar files are different or not, but the hash values would easily tell these files apart if they are different.
Steganography Benefits
It is beneficial for securely storing sensitive data, such as hiding system passwords or keys within other files.