Section- D Cryptography
Cryptography refers to the science and art of transforming messages to make
them secure and immune to attacks. It is a method of storing and transmitting
data in a particular form so that only those for whom it is intended can read and
process it. Cryptography not only protects data from theft or alteration but can
also be used for user authentication.
Components
There are various components of cryptography which are as follows
Plaintext and Ciphertext
The original message, before being transformed, is called plaintext. After
the message is transformed, it is called ciphertext. An encryption
algorithm transforms the plaintext into ciphertext; a decryption algorithm
transforms the ciphertext back into plaintext. The sender uses an
encryption algorithm, and the receiver uses a decryption algorithm.
Cipher
We refer to encryption and decryption algorithms as ciphers. The term
cipher is also used to refer to different categories of algorithms in
cryptography. This is not to say that every sender-receiver pair needs
their very own unique cipher for secure communication. On the contrary,
one cipher can serve millions of communicating pairs.
Key
A key is a number (or a set of numbers) that the cipher, as an algorithm,
operates on. To encrypt a message, we need an encryption algorithm, an
encryption key, and plaintext. These create the ciphertext. To decrypt a
message, we need a decryption algorithm, a decryption key, and the
ciphertext. These reveal the original plaintext.
Types
There are two types of cryptography which are as follows
Symmetric Key Cryptography
In symmetric-key cryptography, the same key is used by both parties.
The sender uses this key and an encryption algorithm to encrypt data; the
receiver uses the same key and the corresponding decryption algorithm to
decrypt the data.
Asymmetric-Key Cryptography
In asymmetric or public-key cryptography, there are two keys: a private
key and a public key. The private key is kept by the receiver. The public
key is announced to the public.
In public-key encryption/decryption, the public key that is used for
encryption is different from the private key that is used for decryption.
The public key is available to the public, and the private key is available
only to an individual.
The Purpose of Cryptography?
Cryptography aims to keep data and messages private and inaccessible to possible
threats or bad actors. It frequently works invisibly to encrypt and decrypt the data you
send through email, social media, applications, and website interactions.
There are several uses for symmetric cryptography, including:
o Payment applications and card transactions
o Random number generation
o Verify the sender's signature to be sure they are who they claim they are
There are several uses for asymmetric cryptography, including:
o Email messages
o SIM card authentication
o Web security
o Exchange of private ke
Features of Cryptography
Cryptography has the following features:
o Confidentiality: The only person who can access information is the one it is
intended for, which is the primary feature of cryptography.
o Integrity: Information cannot be altered while it is being stored or sent from the
sender to the intended destination without the recipient spotting the addition of
new information in Cryptography.
o Non-repudiation: The creator/sender of a message cannot deny his intent to
send information at a future point.
o Authentication: The identities of the sender and the recipient have been
confirmed. Furthermore, the information's source and final destination are
confirmed.
o Availability: It also ensures that the required information is available to
authorized users at the appropriate time.
o Key Management: The creation, distribution, storage, and alteration of
cryptographic keys take place in this process.
o Algorithm: Mathematical formulae are used in cryptography to encrypt and
decrypt messages.
o Digital Signatures: A signature that can be applied to messages to protect the
message's authenticity and sender identification.
Cryptographic Algorithms
Cryptosystems encrypt and decrypt information using cryptographic algorithms, or
ciphers, to secure communications between computer systems, devices, and
applications.
A cipher suite uses three different algorithms: one for encryption, message
authentication, and key exchange. This process, integrated into protocols and
developed using software that runs on operating systems (OS) and networked
computer systems, involves:
o Data encryption and decryption using the production of public and private keys
o To authenticate messages, use digital signature and verification
o Key exchange
Advantages
Access Management: Access control can use cryptography to guarantee that only
individuals with the appropriate authorizations are granted access to a resource. The
resource is encrypted and can only be accessed by those with the proper decryption
key.
Secure Communication: Cryptography is essential for private communication over the
Internet. It provides safe methods for sending sensitive data like bank account
numbers, passwords, and other private information over the Internet.
Protection against attacks: Attacks like replay and man-in-the-middle attacks can be
defended against with the help of cryptography. It provides techniques for identifying
and preventing these assaults.
Compliance with legal requirements: Businesses can use cryptography to help them
deal with several legal obligations, such as data protection and privacy laws.
Applications of Cryptography
Computer passwords: Cryptography is frequently used in computer security, especially
when creating and managing passwords. When users log in, their password is hashed
and contrasted with the previously saved hash. To store them, passwords are first
hashed and encrypted. This method encrypts the passwords so that even if hackers
can access the password database, they can't comprehend the passwords.
Digital Currencies: Cryptography is also used by digital currencies like Bitcoin to secure
transactions and prevent fraud. Since advanced algorithms and cryptographic keys
safeguard transactions, tampering with or creating fake transactions is practically
impossible.
Secure web browsing: Cryptography protects users from eavesdropping in on their
conversations and man-in-the-middle attacks and provides online browsing security.
The Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols use public
key cryptography to encrypt data between the web server and the client, creating a
secure communication channel.
Digital signatures: Digital signatures are used to sign papers and act as the handwritten
signature's digital copy. Cryptography is used to create digital signatures, and public
key cryptography is used to verify them. Digital signatures are becoming more widely
used, and many countries have laws that make them legally binding.
Authentication: When logging into a computer, cryptography is employed as the
authentication method, for example, a bank account or a secure network. The
authentication protocols use cryptographic techniques to validate the user's identity
and possession of the necessary access privileges to the resource.
Cryptocurrencies: Cryptocurrencies like Bitcoin and Ethereum largely rely on
cryptography to protect transactions, prevent fraud, and uphold the integrity of the
network. Transactions are protected by complicated algorithms and cryptographic
keys, making it nearly impossible to tamper with or fake transactions.
