Legal Standing

The US ESIGN Act (2000) defines an electronic signature as “an electronic sound, symbol, or process, attached to or logically associated with a contract or other record and executed or adopted by a person with the intent to sign the record.”

Mark satisfies every element:

• Electronic process — Ed25519 cryptographic signature
• Attached to the record — the SignedBundle includes the document hash and signature
• Intent to sign — the user explicitly taps Sign and authenticates with biometrics
• Attribution — the signature is mathematically linked to the signer's key pair

Under eIDAS, Mark signatures qualify as Advanced Electronic Signatures (AdES) because they are:

• Uniquely linked to the signatory (Ed25519 key pair)
• Capable of identifying the signatory (service record with identity claims)
• Created using data under the signatory's sole control (Secure Enclave / YubiKey)
• Linked to the data in such a way that any change is detectable (document hash in signed bundle)

For Qualified Electronic Signature (QES) status — which has the legal equivalence of a handwritten signature in the EU — Mark would need to use a Qualified Signature Creation Device (QSCD) and be issued by a Qualified Trust Service Provider (QTSP). This is on the roadmap.

Mark signatures carry stronger evidence than most e-signature platforms because:

• Non-repudiation — the signer cannot deny signing without proving key compromise
• Tamper evidence — any modification to the document invalidates the signature
• Independent verification — no reliance on Mark's servers or testimony
• Temporal proof — Bitcoin/OTS timestamps provide independent time evidence
• Hardware attestation — T4 signers can prove the key was in certified hardware

In a dispute, a Mark signature provides a complete, self-contained evidence package that any cryptographer can verify independently.

This page is informational, not legal advice. Electronic signature laws vary by jurisdiction and document type. Some documents (wills, certain real estate transfers, court orders) may require wet signatures or notarization regardless of the e-signature framework. Consult qualified legal counsel for your specific use case.