Two Terms, Often Used as if Interchangeable
"Electronic signature" and "digital signature" get used casually as synonyms, but they refer to genuinely different things — one is a broad legal category, the other a specific cryptographic technique. Every digital signature is an electronic signature, but not every electronic signature is a digital signature.
Electronic Signature: The Legal Category
Under the U.S. ESIGN Act, an electronic signature is defined broadly as "an electronic sound, symbol, or process, attached to or logically associated with a contract or record and executed or adopted by a person with the intent to sign the record." That definition covers a typed name, a mouse-drawn signature image, or even clicking an "I agree" button — all of it counts as a legally valid electronic signature under U.S. and most international law.
Digital Signature: The Cryptographic Method
A digital signature is a specific technical implementation using Public Key Infrastructure (PKI). A Certificate Authority verifies the signer's identity and issues a digital certificate containing a public/private key pair. When signing, a cryptographic hash of the document's exact contents is generated and encrypted with the signer's private key. If the document changes afterward by even a single character, the hash no longer matches — making tampering immediately detectable.
What a Drawn Signature Doesn't Provide
A drawn or uploaded signature image placed on a PDF page — the kind produced by most simple online signing tools — is a genuine, legally valid electronic signature. It is not, however, cryptographically tied to the document's contents, and doesn't independently verify who actually drew it. That verification typically relies on other evidence instead — an audit trail showing who accessed the document, when, and from where.
Why the Distinction Has Real Stakes
For routine, low-risk documents — internal approvals, simple agreements, most everyday paperwork — a standard electronic signature is entirely sufficient and just as legally binding. For regulated industries, high-value contracts, or situations where tamper-evidence and verified identity genuinely matter for legal or compliance reasons, a true PKI-based digital signature provides meaningfully stronger assurance that a drawn signature image alone cannot.
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