Nyckelparkryptering

Nyckelparkryptering, also known as public-key cryptography, is a system of encryption that uses a pair of keys: a public key and a private key. These keys are mathematically related, but it is computationally infeasible to derive the private key from the public key.

The public key can be shared freely with anyone, while the private key must be kept secret by its owner. Data encrypted with a public key can only be decrypted with the corresponding private key. Conversely, data encrypted with a private key can be decrypted with the corresponding public key, which is the basis for digital signatures.

This dual-key system allows for secure communication and authentication without the need for a pre-shared secret key. It is widely used in various applications, including secure email (PGP), secure web browsing (SSL/TLS), and cryptocurrency transactions.

The underlying mathematical principles often involve number theory, such as prime factorization or discrete logarithms. For instance, the RSA algorithm, a common implementation of nyckelparkryptering, relies on the difficulty of factoring large numbers into their prime components. Other algorithms like Diffie-Hellman establish a shared secret key over an insecure channel, and Elliptic Curve Cryptography (ECC) offers similar security levels with smaller key sizes.