What sources or data are used to generate an electronic signature?

An electronic signature is formed based on the data that needs to be signed and the signer's private key. The main data sources for the signature are:

• The original document or message (e.g., a file, text, transaction).
• A hash (checksum) of this document, which is calculated for a compact representation of the data.
• The signer's private (secret) key, used to create the signature.

Process: first, the hash of the document is calculated, then this hash is encrypted with the private key, resulting in the electronic signature. The recipient can verify the signature using the signer's public key.