Cryptography

Cryptography

Cryptography is a technique of securing information and communications using codes to ensure confidentiality, integrity and authentication. Thus, preventing unauthorized access to information. The prefix "crypt" means "hidden" and the suffix "graphy" means "writing". In Cryptography, the techniques that are used to protect information are obtained from mathematical concepts and a set of rule-based calculations known as algorithms to convert messages in ways that make it hard to decode them.

Features Of Cryptography

The features of cryptography that makes it a popular choice in various applications could be listed down as

1. Confidentiality: Information can only be accessed by the person for whom it is intended and no other person except him can access it.
2. Non-repudiation: The creator/sender of information cannot deny his intention to send information at a later stage.
3. Integrity: Information cannot be modified in storage or transition between sender and intended receiver without any addition to information being detected.
4. Adaptability: Cryptography continuously evolves to stay ahead of security threats and technological advancements.

Working of Cryptography

As we all know that cryptography technique is use to convert plain text into ciphertext. This technique is done by cryptographic key. Basically cryptographic key is a string of characters which is used to encrypts the data and decrypt the data.

Applications of Cryptography

Cryptography has wide area of applications in the modern world, where the technology is rapidly evolving. From authentication measures to cryptocurrencies, cryptography is here to stay, these are some of the most common applications of cryptography listed below:

Cryptography Attacks-

cryptography attack can be either passive or active.

Cryptographic attacks generally fall into two categories:

• Passive Attacks: These focus on interception and analysis. Attackers monitor communication channels to extract sensitive information without altering the data flow. Examples include traffic analysis and eavesdropping, where attackers capture ciphertext and use statistical methods to infer patterns.

• Active Attacks: These involve direct manipulation or injection. The attacker not only gains access to the data but also modifies, corrupts, or impersonates communication to alter outcomes. Active attacks are far more destructive, often forming the backbone of man-in-the-middle (MITM) exploits or ciphertext modification attempts.

• Types of Cryptography Attacks

  Depending on the type of cryptographic system in place and the information available to the attacker, these attacks can be broadly classified into six types:

  • Brute force attacks: Public and private keys play a significant role in encrypting and decrypting the data in a cryptographic system. In a brute force attack, the cybercriminal tries various private keys to decipher an encrypted message or data. If the key size is 8-bit, the possible keys will be 256 (i.e., 28). The cybercriminal must know the algorithm (usually found as open-source programs) to try all the 256 possible keys in this attack technique.

  • Ciphertext-only attacks: In this attack vector, the attacker gains access to a collection of ciphertext. Although the attacker cannot access the plaintext, they can successfully determine the ciphertext from the collection. Through this attack technique, the attacker can occasionally determine the key.

  • Chosen plaintext attacks: Here, the cybercriminal can choose arbitrary plaintext data to obtain the ciphertext. It simplifies the attacker's task of resolving the encryption key. One well-known example of this type of attack is the differential cryptanalysis performed on block ciphers.

  • Chosen ciphertext attack: In this attack model, the cybercriminal analyzes a chosen ciphertext corresponding to its plaintext. The attacker tries to obtain a secret key or the details about the system. By analyzing the chosen ciphertext and relating it to the plaintext, the attacker attempts to guess the key. Older versions of RSA encryption were prone to this attack.

  • Known plaintext attacks: Via this technique, the cybercriminal finds or knows the plaintext of some portions of the ciphertext using information gathering techniques. Linear cryptanalysis in block cipher is one such example.

  • Key and algorithm attacks: Here, the attacker tries to recover the key used to encrypt or decrypt the data by analyzing the cryptographic algorithm.

  • 
    

Types Of Cryptography

There are three types of cryptography, namely Symmetric Key Cryptography, Asymmetric Key Cryptography and Hash functions, here's a detailed explanation below

Difference Between Private Key and Public Key cryptography

Private Key	Public Key
The private key is faster than the public key.	It is slower than a private key.
In this, the same key (secret key) and algorithm are used to encrypt and decrypt the message.	In public-key cryptography, two keys are used, one key is used for encryption, and the other is used for decryption.
In private key cryptography, the key is kept a secret.	In public-key cryptography, one of the two keys is kept a secret.
The private key is Symmetrical because there is only one key that is called a secret key.	The public key is Asymmetrical because there are two types of keys: private and public keys.
In this cryptography, the sender and receiver need to share the same key.	In this cryptography, the sender and receiver do not need to share the same key.
It is used for large amounts of text.	It is used for only short messages.
The private key is to be shared between two parties.	The public key can be used by anyone.
The Performance testing checks the reliability, scalability, and speed of the system.	The Load testing checks the sustainability of the system.
The private key is used in algorithms such as AES 128, AES 192 and AES 256.	The public key is used in algorithms such as RSA, DSA, etc.
It is used to protect disk drives and other data storage devices.	It is used to secure web sessions and emails.
The recipient's private key decrypts the message.	The recipient's public key encrypts the message.
If the private key is the locking key, then the system can be used to verify documents sent by the holder of the private key.	If the public key is the locking key, then it can be used to send private communication.

Symmetric Key Cryptography

Symmetric Key Cryptography is an encryption system where the sender and receiver of a message use a single common key to encrypt and decrypt messages. Symmetric Key cryptography is faster and simpler but the problem is that the sender and receiver have to somehow exchange keys securely. The most popular symmetric key cryptography systems are Data Encryption Systems (DES) and Advanced Encryption Systems (AES) .

1.    Data Encryption Standard (DES)

DES (Data encryption standard) is an older encryption algorithm that is used to convert 64-bit plaintext data into 48-bit encrypted ciphertext. It uses symmetric keys (which means same key for encryption and decryption). It is kind of old by today’s standard but can be used as a basic building block for learning newer encryption algorithms.

2.    AES (Advanced Encryption Standard):

AES is a popular encryption algorithm which uses the same key for encryption and decryption It is a symmetric block cipher algorithm with block size of 128 bits, 192 bits or 256 bits. AES algorithm is widely regarded as the replacement of DES (Data encryption standard) algorithm.

Asymmetric Key Cryptography

In Asymmetric Key Cryptography a pair of keys is used to encrypt and decrypt information. A sender's public key is used for encryption and a receiver's private key is used for decryption. Public keys and Private keys are different. Even if the public key is known by everyone the intended receiver can only decode it because he holds his private key. The most popular asymmetric key cryptography algorithm is the RSA algorithm.

RSA (Rivest-Shamir-Adleman):

RSA is an basic asymmetric cryptographic algorithm which uses two different keys for encryption. The RSA algorithm works on a block cipher concept that converts plain text into cipher text and vice versa.