Kryptograafias

Kryptograafias, also known as cryptography, is the practice and study of techniques for secure communication in the presence of third parties called adversaries. It involves methods for transforming information into a format that is unintelligible to unauthorized parties, while still allowing authorized parties to decrypt and access the original information. This field is fundamental to modern information security, protecting everything from online transactions and private messages to sensitive government communications.

The core components of cryptography are encryption, which is the process of converting readable data (plaintext) into an unreadable format (ciphertext), and decryption, the reverse process of converting ciphertext back into plaintext. These operations are performed using algorithms and keys. Keys are secret pieces of information that control the behavior of the encryption and decryption algorithms.

Historically, cryptography relied on symmetric-key algorithms, where the same key is used for both encryption and decryption. However, the challenge of securely exchanging these secret keys led to the development of asymmetric-key cryptography, also known as public-key cryptography. In this system, a pair of mathematically related keys is used: a public key, which can be shared widely, and a private key, which must be kept secret. Data encrypted with a public key can only be decrypted with its corresponding private key, and vice versa. This enables secure communication and digital signatures without the need for prior key exchange. Modern cryptography encompasses a wide range of techniques, including hashing, digital signatures, and advanced encryption standards, all contributing to the security and integrity of digital information.