Kriptografia

Kriptografia is the practice and study of techniques for secure communication in the presence of adversarial behavior. The term is derived from the Greek words kryptos meaning "hidden" and graphein meaning "writing". At its core, cryptography involves transforming readable information, known as plaintext, into an unreadable format called ciphertext. This process is achieved using algorithms and keys.

The primary goal of cryptography is to ensure confidentiality, integrity, authentication, and non-repudiation. Confidentiality ensures that only authorized parties can access the information. Integrity guarantees that the data has not been altered during transmission or storage. Authentication verifies the identity of the sender or receiver. Non-repudiation prevents a party from denying their involvement in a transaction.

There are two main types of cryptography: symmetric-key cryptography and asymmetric-key cryptography, also known as public-key cryptography. In symmetric-key cryptography, the same key is used for both encryption and decryption. This method is fast but requires a secure way to share the key. Asymmetric-key cryptography uses a pair of keys: a public key for encryption and a private key for decryption. This overcomes the key distribution problem of symmetric-key cryptography and is fundamental to many modern security protocols.

Cryptography plays a vital role in various aspects of modern life, including secure online transactions, digital signatures, virtual private networks (VPNs), and protecting sensitive data. Its principles are constantly evolving to counter new threats and maintain the security of information in an increasingly digital world.