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Glossary Security

Digital signature

A digital signature is a value computed from a message and a private key that proves who created it and that it has not been changed.

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In more detail

The signer hashes the message and transforms the hash with their private key; anyone can check the result with the matching public key (Public-key cryptography). Changing even one bit of the message breaks the signature. Signatures protect software updates, certificates, signed PDFs and DKIM email.

See also

  • Glossary Public-key cryptography
    Public-key (asymmetric) cryptography uses a pair of linked keys: a public key anyone can have, and a private key kept secret.
  • Glossary Hash
    A hash is the fixed-length fingerprint a hash function computes from any input; the same input always gives the same hash.
  • Glossary Digital certificate
    A digital certificate is a signed file that links a public key to an identity, such as a domain name, so others can trust that key.
  • Glossary DKIM
    DKIM (DomainKeys Identified Mail) adds a digital signature to outgoing email that receivers verify with a public key published in DNS.
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