Signi.com & Electronic Signatures

Foundation – eIDAS Signature Levels

Under EU law (eIDAS 910/2014), electronic signatures can be:

• SES – Simple Electronic Signature (basic: typed name, click-to-sign, tickbox).

• AdES – Advanced Electronic Signature (cryptographically bound to the signer, integrity-protected).

• QES – Qualified Electronic Signature (requires a qualified certificate + secure signing device; legally equivalent to handwritten signature in the EU).

👉 Signi supports SES, AdES, and in certain cases QES (e.g. with BankID or qualified certificates).

SMS-Based Signer Verification

How It Works

1. Signer Identification

   • Signi asks for the signer’s mobile number.

   • The system sends a one-time code (OTP) via SMS.

2. OTP Entry

   • The signer enters the OTP on the Signi platform.

   • If the code matches, Signi confirms the signer’s control of that phone number.

3. Binding to Document

   • Signi records:

     • Mobile number used

     • IP address

     • Timestamp of verification

   • The verification is stored in the audit trail attached to the signed document. 

Signature Level

• SMS verification alone is considered “Simple Electronic Signature (SES)”.

• It does not use a cryptographic certificate by default.

• Legally:

  • SES is sufficient for internal approvals or contracts between trusted parties.

  • SES is not automatically QES or advanced (AdES) — i.e., it may be challenged in court if the signer’s identity is disputed.

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3️⃣ Combining SMS with Stronger Methods

• Some platforms combine SMS verification with cryptographic signatures or BankID:

  • The SMS ensures the signer received the document.

  • The crypto certificate binds the signature to the document securely.

• This approach increases legal weight, approaching AdES.

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4️⃣ Security Considerations

• Pros

  • Easy to use, no special device required.

  • Lightweight and fast.

• Cons

  • SMS is vulnerable to SIM swapping or interception.

  • Not legally equivalent to handwritten signatures in most EU jurisdictions on its own.

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✅ In short: SMS authentication in Signi is a convenient way to verify signer control, but it doesn’t replace a qualified or advanced electronic signature if strong legal enforceability is required.