Electronic signatures have replaced wet ink for millions of contracts every day. But how do they actually work — and why does a court accept them as valid? This guide breaks down the technology and law behind e-signatures.
What Is an Electronic Signature?
An electronic signature is any electronic indication of intent to agree to a document. This can be as simple as typing your name, drawing your signature with a mouse, or clicking an “I agree” button. The legal validity comes not from the form of the signature, but from the intent and the audit trail that proves it.
Under eIDAS (EU), the ESIGN Act (US), and UETA, an e-signature is legally equivalent to a handwritten signature as long as it:
- Identifies the signer uniquely
- Is linked to the document being signed
- Is created with data under the signer’s sole control
- Can detect any subsequent changes to the document
The Technology Inside
1. Document Fingerprinting (Hashing)
When you upload a document to Tenrion, we calculate a unique cryptographic hash — think of it as a fingerprint — of the file. If even a single character changes after signing, the hash changes, proving tampering.
We use SHA-256, the same algorithm used in TLS/HTTPS across the web.
2. Timestamping
Every action — document upload, signer invite, signature click — is logged with a cryptographically certified timestamp from a trusted timestamp authority (TSA). This makes the audit trail tamper-proof and independently verifiable.
3. Signer Authentication
Tenrion authenticates each signer through:
- Email verification — signers click a unique, expiring link sent to their email
- Knowledge-based authentication (KBA) — optional identity questions
- SMS verification — one-time passcode to a verified phone number (Business Pro)
4. Signature Capture
The signer’s action (drawing, typing, or clicking) is captured along with their IP address, device fingerprint, time, and geolocation. This data is embedded in the envelope’s audit trail.
5. Audit Trail Sealing
When the last signer completes the document, Tenrion seals the entire envelope — document + signatures + audit log — into a single PDF with an embedded certificate. This certificate includes all hashes and timestamps, allowing any third party to independently verify the document’s integrity.
Why Courts Accept E-Signatures
Courts care about two things: attribution (who signed?) and integrity (has the document changed?). Tenrion’s cryptographic audit trail answers both questions definitively, making our signatures court-admissible under eIDAS, ESIGN, UETA, and equivalent laws in 180+ countries.
Standard vs. Advanced vs. Qualified Signatures
The EU’s eIDAS regulation defines three tiers:
| Type | Authentication | Use Case |
|---|---|---|
| Standard (SES) | Email/click | Most commercial contracts |
| Advanced (AES) | Cryptographic key tied to identity | Higher-value agreements |
| Qualified (QES) | In-person identity verification | Notarial acts, real estate |
Most business contracts — NDAs, employment agreements, sales contracts — are signed using Standard Electronic Signatures, which Tenrion provides out of the box.
Getting Started
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