Cryptography is the science of using mathematical techniques to secure communication and protect data from unauthorized access or manipulation. Derived from the Greek words kryptos (secret) and graphein (writing), it underpins nearly all modern digital security, from secure web browsing to online banking. The Core Vocabulary
To understand cryptography, you must first know its foundational terms:
Plaintext: The original, readable message or data before it is hidden.
Ciphertext: The scrambled, unreadable version of the message after processing.
Cipher: The specific mathematical algorithm used to convert plaintext to ciphertext.
Key: A secret piece of data (like a password or string of random numbers) required by the cipher to encrypt or decrypt information. The Four Pillars of Cryptography
Modern cryptosystems are designed to achieve four core security objectives:
Confidentiality: Ensuring that only authorized recipients can read the data.
Integrity: Verifying that the data was not modified or tampered with during transit.
Authentication: Proving the identity of the sender and the receiver.
Non-repudiation: Preventing a sender from denying they sent a message. The Three Main Cryptographic Types
Cryptography is categorized into three primary mechanisms based on how keys are managed:
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