Cryptography Explained

Cryptography Dark Osint

Cryptography Explained - Cryptography is science of securing digital information through mathematical algorithms. Learn about encryption, decryption, and essential role of cryptography in protecting online data.

Where data is constantly exchanged across internet, security has become more important than ever. From online banking and e-commerce to encrtypted messaging and digital signatures, protection of sensitive information is a top priority. This is where cryptography plays a vital role.

Cryptography is science and practice of securing information and communication using mathematical concepts and algorithms. It transforms readable data (plaintext) into an unreadable format (ciphertext) and ensures that only authorized parties can access it with correct key. By doing so, cryptography guarantees confidentiality, integrity, authentication, and non repudiation in digital world.

What is Cryptography?

At its core, cryptography ensures that digital communication and stored data remain secure from unauthorized access. It is widely used in applications such as:

• Internet security (SSL/TLS protocols)
• Online banking and financial transactions
• Secure communication apps (e.g., WhatsApp, Signal)
• Authentication systems (password hashing, digital certificates)
• Data storage protection (encrypted databases and files)

To fully understand how cryptography works, let’s break down fundamental concepts:

• Encryption: Process of converting plaintext into ciphertext using an algorithm and a key.
• Decryption: Reverse process of encryption, converting ciphertext back into readable plaintext using correct key.
• Plaintext: Original, human readable data or message.
• Ciphertext: Sscrambled, unreadable version of data after encryption.
• Algorithm: A mathematical method used for encryption and decryption.
• Key: A secret value used by algorithm to lock (encrypt) and unlock (decrypt) data.

Cryptography provides four main security functions:

Confidentiality

Ensures that data can only be accessed by authorized individuals.

Integrity

Protects data from being altered or tampered with by unauthorized parties.

Authentication

Confirms identity of sender and receiver, ensuring data comes from a legitimate source.

Non Repudiation

Prevents sender from denying that they sent a message or performed a transaction.

Types of Cryptography

There are two primary types of cryptography used in digital security:

1. Symmetric key cryptography

• Uses a single shared secret key for both encryption and decryption.

• Fast and used for bulk encryption (files, TLS bulk data).

• Block ciphers (e.g., AES) operate on fixed size blocks (128 bits). Stream ciphers (e.g., ChaCha20) produce a keystream XOR’ed with plaintext.

• Modes of operation for block ciphers matter: ECB (bad), CBC, CTR, GCM (authenticated). Authenticated encryption (AE/AEAD, e.g., AES GCM, ChaCha20 Poly1305) combines confidentiality + integrity in a single primitive prefer AEAD.

2. Asymmetric (public key) cryptography

• Uses a key pair: public key (shared) and private key (kept secret).

• Enables confidentiality (encrypt to a recipient’s public key), authentication (sign with a private key), and secure key exchange.

• Examples: RSA, Diffie Hellman (DH), Elliptic Curve Cryptography (ECC) (e.g., ECDH for key exchange, Ed25519/ECDSA for signatures).

• Asymmetric ops are computationally heavier; commonly used to establish symmetric keys, not for bulk data.

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