cryography

Cryptography is the practice and study of techniques for secure communication in the presence of adversaries. It involves methods for transforming information to make it unintelligible to anyone who is not authorized to see it. This process is known as encryption, and the reverse process, which restores the original information, is called decryption.

The fundamental goal of cryptography is to ensure confidentiality, integrity, authentication, and non-repudiation. Confidentiality means that only authorized parties can understand the information. Integrity ensures that the information has not been altered during transmission. Authentication verifies the identity of the sender or receiver. Non-repudiation prevents a sender from denying that they sent a message.

Cryptography is broadly divided into two main categories: symmetric-key cryptography and asymmetric-key cryptography. Symmetric-key cryptography uses a single secret key for both encryption and decryption. This key must be shared securely between the sender and receiver. Asymmetric-key cryptography, also known as public-key cryptography, uses a pair of keys: a public key for encryption and a private key for decryption. The public key can be freely shared, while the private key must be kept secret by its owner.

Modern cryptography relies heavily on mathematical algorithms and computational complexity to achieve its security goals. It is a critical component in many modern technologies, including secure web browsing (HTTPS), email encryption, digital signatures, and cryptocurrencies, playing a vital role in protecting sensitive data and ensuring trust in digital communications.