eallkirja

Eallkirja is the term used for electronic signatures, a method of signing documents digitally so their integrity can be verified and the signer's identity can be established without a handwritten signature. Electronic signatures are based on cryptographic techniques and can be used for personal, business, and government transactions, enabling faster and paperless workflows while providing evidence of authorship and tamper resistance.

In the European Union, electronic signatures are governed by the eIDAS Regulation, which defines three levels: simple electronic signatures (SES), advanced electronic signatures (AES), and qualified electronic signatures (QES). A QES uses a qualified certificate issued by a trusted service provider and a secure signature creation device, and it has the same legal effect as a handwritten signature across EU member states. An AES is linked to the signer and capable of identifying them, offering stronger assurance than SES but not always carrying the same legal weight as a handwritten signature. SES has the lowest level of assurance and its legal effect varies by jurisdiction.

Technically, eallkirja relies on public key infrastructure (PKI). The signer uses a private key to generate a cryptographic signature on the document, and others use the corresponding public key and certificate to verify it. Certificates are issued by trusted certificate authorities and can be revoked if compromised. Signatures are typically tamper-evident and may be time-stamped to prove when they were created.

Applications include signing contracts, tax forms, official documents, and interactions with e-government portals. In Estonia, electronic signatures are tightly integrated with national digital ID systems (such as ID-card, Mobile ID, and Smart-ID) and services like X-Road, supporting secure and rapid public-sector and private-sector transactions. As with any cryptographic system, secure key management and trusted verification services are essential to maintain trust in eallkirja.