publickeykryptering

Publickey encryption, also known as asymmetric encryption, is a cryptographic system that uses a pair of keys: a public key and a private key. The public key can be freely distributed and is used to encrypt messages. The private key, which must be kept secret by its owner, is used to decrypt messages that were encrypted with the corresponding public key. This system ensures that only the intended recipient, who possesses the private key, can read the encrypted message.

The fundamental principle behind publickey encryption is the existence of mathematical problems that are easy to solve in one direction but extremely difficult to reverse. For example, multiplying two large prime numbers is easy, but factoring a large number into its prime factors is computationally infeasible. Publickey algorithms leverage such problems to generate key pairs. When a user generates a key pair, their public key is shared, allowing anyone to encrypt a message for them. However, without the private key, decrypting that message becomes practically impossible.

This technology has revolutionized secure communication and digital security. It forms the backbone of many internet security protocols, including SSL/TLS, which secures web browsing. It is also used in digital signatures, where a message is "signed" with the sender's private key, and anyone can verify the signature using the sender's public key, confirming the message's authenticity and integrity. The ability to encrypt and verify without prior secure exchange of secret keys makes publickey encryption a cornerstone of modern cryptography.