Chapter 4. Building the base scenario: Stage 1 97
4.6.4 Adding Signature buttons
Digital signatures have two purposes:
Identifying signers:
Digital signatures affix the signer’s name and e-mail address to the document.
Secure documents:
Digital signatures use encryption algorithms and digital certificates to guarantee form
security.
When users sign a document, a “snapshot” of the document is taken and hashed to produce
a unique number representing your document. If the document changes, hashing produces a
different number. As a result, you can think of a hash as a document’s digital fingerprint,
unique and unmistakable.
In other words, once users have signed a form, any alterations to the signed portion of the
form breaks the signature. F