Cryptography Fundamentals

What is Crypto?

• Crypto, short for cryptography, refers to the practice and study of techniques for secure communication in the presence of third-party adversaries.
• It involves the use of algorithms and protocols to protect the confidentiality, integrity, and authenticity of messages.

Types of Cryptography

• Symmetric-key cryptography: uses the same secret key for both encryption and decryption.
• Asymmetric-key cryptography: uses a pair of keys, one public and one private, for encryption and decryption.

Cryptographic Techniques

• Encryption: the process of converting plaintext into ciphertext.
• Decryption: the process of converting ciphertext back into plaintext.
• Hashing: a one-way function that takes input data of any size and returns a fixed-size string of characters.
• Digital signatures: used to authenticate the sender of a message and ensure the integrity of the message.

Cryptographic Algorithms

• AES (Advanced Encryption Standard): a symmetric-key block cipher used for encryption.
• RSA (Rivest-Shamir-Adleman): an asymmetric-key algorithm used for encryption and digital signatures.
• SHA (Secure Hash Algorithm): a family of hash functions used for data integrity and authenticity.

Cryptocurrencies

• Blockchain: a decentralized, distributed ledger that records transactions across a network of computers.
• Bitcoin: the first decentralized cryptocurrency, launched in 2009.
• Altcoins: alternative cryptocurrencies that are not Bitcoin, such as Ethereum, Litecoin, and others.

Cryptographic Applications

• Secure online transactions: crypto is used to secure online transactions, such as online banking and e-commerce.
• Secure communication: crypto is used to secure communication, such as HTTPS and VPNs.
• Digital identity: crypto is used to secure digital identities, such as passports and identity cards.