Digital signature
A digital signature is a cryptographic signature, made with a private key tied to a certificate, that lets anyone check who signed a file and whether it has changed since.
Updated October 13, 2026 · 1 min read
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How it works
Software computes a fingerprint (a hash) of the file and signs it with the signer's private key. A reader uses the public key in the signer's certificate to verify it. If even one character of the file changes afterward, the check fails. NIST's Digital Signature Standard puts it simply: digital signatures detect unauthorized changes and authenticate the signatory.
Digital vs electronic
A digital signature is one technology for signing. An electronic signature is the broader legal idea. US law doesn't require certificates, while the EU's eIDAS Regulation gives automatic handwritten-equivalent status only to qualified signatures, which rely on qualified certificates.
SignMaster doesn't add certificate-based digital signatures. It records a SHA-256 fingerprint of each original file, checks the files against it before building the signed PDF, and prints the fingerprints on the certificate of completion. The full comparison is in electronic vs digital signatures.
Questions? Answers.
Does SignMaster use digital signatures?
No. SignMaster collects electronic signatures and backs them with an audit trail and SHA-256 fingerprints of each file, printed on the certificate of completion. It doesn't add a certificate-based digital signature to the PDF.
Sources
- NIST FIPS 186-5, Digital Signature Standard (2023) · csrc.nist.gov
- Regulation (EU) No 910/2014 (eIDAS), Articles 3, 25 and 26 (EUR-Lex) · eur-lex.europa.eu