Signaturwert

Signaturwert is the cryptographic value produced when a message is digitally signed. It is the result of applying the signer's private key to a message digest, creating a value that can be used to verify the authenticity and integrity of the message. The signaturwert, together with the chosen signing algorithm and the signer's public key (often contained in a certificate), enables a recipient to confirm that the message originated from the claimed signer and has not been altered.

In a typical signing process, a hash of the message is created and then encrypted with the signer's private key to produce the signaturwert. During verification, the recipient uses the corresponding public key to decrypt the signaturwert, obtaining the digest, and compares it with a newly computed digest of the received message. A match indicates that the signature is valid and the data intact.

Signaturwerte are usually encoded for transport or storage, for example as base64 or hexadecimal strings, and appear in formats such as XML Signature (SignatureValue), CMS/PKCS#7, or PGP signatures. The signaturwert is not an identifier on its own; it is linked to a specific signing operation and message, and its validity depends on the security of the signer's private key and the trust in the certificate chain.

Legal and practical use requires proper key management, secure storage of private keys, and recognition under electronic-signature regulations in relevant jurisdictions (for example, qualified electronic signatures under EU law). The term is commonly used in cryptographic contexts to denote the signature value itself.