Digital signing of an agreement / contract.

The answer is almost certainly yes, but it may depend on which jurisdiction's law applies, which I can't tell from your question.  Many (probably nearly all) American jurisdictions now have statutes which make electronic signatures as binding as handwritten ones, although some impose certain conditions.  For example, the Electronic  Signatures in Global and National Commerce Act, 15 U.S.C. Section 7001 et seq (a federal statute), the Electronic Signatures and Records Act, Title 540 of the New York State Technology Law, and the Connecticut Uniform Electronic Transactions Act, Section 1-266 et seq of the Connecticut General Statutes.