Signaturordninger

Signaturordninger, often translated as signature schemes or signing systems, are cryptographic protocols that allow a party to digitally sign a message or document. This signature provides authenticity, integrity, and non-repudiation for the signed data. Authenticity ensures that the message originates from the claimed sender, integrity confirms that the message has not been altered since it was signed, and non-repudiation prevents the sender from later denying that they sent the message.

The core principle behind signature schemes relies on asymmetric cryptography, also known as public-key cryptography. Each user has a pair of keys: a private key, which is kept secret, and a public key, which can be shared with anyone. To create a signature, the sender uses their private key to encrypt a hash of the message. This encrypted hash is the digital signature.

To verify the signature, the recipient uses the sender's public key to decrypt the signature. If the decrypted value matches the hash of the received message, the signature is considered valid. This process confirms that the message was indeed signed by the holder of the corresponding private key and that the message has not been tampered with. Common signature schemes include RSA, DSA (Digital Signature Algorithm), and ECDSA (Elliptic Curve Digital Signature Algorithm), each offering different trade-offs in terms of security, performance, and key size. These schemes are fundamental to secure communication and transactions in various digital applications.