Digital Signature PKI for Secure Signatures

Award-winning eSignature solution

What digital signature pki means

Digital signature PKI is a public key infrastructure that uses cryptographic keys and digital certificates to prove who signed a document and to protect the document from changes after signing. In practice, a trusted certificate authority issues a certificate that links a signer’s identity to a public key. The signer uses a private key to create the signature, and the recipient verifies it with the public key. That process confirms identity, integrity, and, when needed, revocation status.

Why digital signature PKI matters

It helps organizations reduce disputes, speed approvals, and preserve evidence of who signed, when, and how. Under ESIGN and UETA, an electronic signature can be enforceable when intent, consent, and attribution are supported by reliable records.

Why teams look for DocuSign alternatives

Common PKI pain points

Certificate revocation checks can fail if OCSP or CRL data is unavailable during verification.
Weak identity proofing can leave signer attribution open to challenge in later disputes.
Poor key management can expose private keys and undermine the trust chain.
Incomplete audit records can make it harder to prove intent, timing, and document integrity.

Business workflows

Teams use digital signature PKI for contracts, approvals, disclosures, and records that need stronger identity assurance.

Document types

It fits onboarding packets, consent forms, lease files, loan documents, and regulated approvals across U.S. operations.

Typical users and personas

A director of NetSuite operations in manufacturing or distribution may need PKI-backed signatures for routed approvals, system-generated documents, and integration-driven workflows. Kodi-Marie Evans at Xerox described signNow as flexible for getting the right signatures on the right documents in the right formats through NetSuite.
A founder or COO in real estate, healthcare, or services may use PKI-backed signing to keep remote transactions moving while preserving audit evidence. Tim Martin at Martin Properties and Brian Fitzgibbons at Optica Ventures LLC both pointed to simple workflows that worked for staff and customers alike.

be ready to get more

Get legally-binding signatures now!

Start free trial

Request a call

Best ROI. Our customers achieve an average 7x ROI within the first six months.
Scales with your use cases. From SMBs to mid-market, airSlate SignNow delivers results for businesses of all sizes.
Intuitive UI and API. Sign and send documents from your apps in minutes.

Identity binding

Creates a cryptographic link between the signer, the certificate, and the signed file so later changes are detectable.

Certificate trust

Uses certificate-based verification to support stronger attribution than a simple drawn signature or checkbox.

Tamper evidence

Preserves a tamper-evident record that helps show document integrity after signing is complete.

Revocation status

Supports revocation checks so expired or revoked certificates can be identified during validation.

Audit evidence

Provides a clear signing history with timestamps, identity details, and document actions for review.

Compliance fit

Fits regulated and cross-border workflows where stronger assurance is needed for enforceability and recordkeeping.

Integrations for connected signing

Connected systems move signed documents, signer data, and status updates into the tools teams already use every day.

How PKI signing works

The signing flow follows a short cryptographic sequence that ties identity, document integrity, and verification together.

Issue certificate: A certificate authority issues a certificate that binds identity to a public key.
Create signature: The signer uses a private key to create the digital signature.
Verify signature: The recipient verifies the signature with the public key and certificate chain.
Check validity: Revocation and timestamp checks confirm the signature still validates over time.

Quick setup steps

Use a short setup sequence to get a PKI-backed signing workflow ready for daily use.

Set identity:
Choose the certificate and signer identity method.
Prepare file:
Upload the document and place signature fields.
Request signing:
Send the request and collect the signature.
Archive record:
Review the completed record and store it securely.

Setting	Recommendation
Authentication method	SMS OTP plus ID verification
Signature type	PKI-backed digital signature
Audit trail	Enable full event logging
Document retention	6 years for HIPAA records
Encryption	TLS 1.2/1.3 and AES-256

Platform and device support

Digital signature PKI works across modern browsers and mobile devices, with secure transport over TLS and support for signing on desktop or phone.

Desktop browsers Chrome, Firefox, Safari, and Edge
Operating systems Windows 11, macOS, iOS, and Android
Mobile access signNow mobile apps on iOS and Android

For enterprise use, managed Windows and macOS devices, mobile apps on iOS and Android, and browser-based access in Chrome, Firefox, Safari, or Edge are the most practical options. Organizations that need SSO, API access, or regulated retention should also confirm certificate handling, device policy, and export controls before rollout.

Security and compliance

Transport security:

TLS 1.2/1.3 in transit

Storage encryption:

AES-256 at rest

Control assurance:

SOC 2 Type II available

Security management:

ISO 27001 certified

Healthcare compliance:

HIPAA support with BAA

Regulated records:

21 CFR Part 11 support

Enterprise operations

A distribution and software company needed faster internal and external approvals without losing control over document formats or routing.

Tech Data used signNow to improve speed to revenue.
The team kept workflows flexible across document types.

Tech Data reported better customer service and faster movement from request to signed record. The case shows how PKI-backed signing can fit routed approvals, integration-heavy environments, and documents that need consistent handling across teams and systems.

Real estate

A property business needed online execution with strong evidence, mobile access, and reliable security for remote transactions.

Martin Properties processed documents online.
Mobile and offline signing stayed available.

Martin Properties described 100% compliance and built-in security in its workflow. For real estate teams, PKI-backed signing can support remote execution, preserve evidence, and reduce paper handling while keeping records organized for later review.

Best practices for PKI signing

Good PKI practice focuses on identity, evidence, retention, and verification rather than the signature image alone.

Strengthen signer identity

Use stronger identity checks for contracts, regulated forms, and any workflow where signer attribution may be questioned later. Pair the signature with a clear consent record and a complete audit trail so the evidence supports ESIGN and UETA enforceability.

Control key access

Protect private keys and certificate access with role-based permissions, device controls, and limited administrative access. Separate signing authority from system administration where possible, and review access when staff change roles or leave the organization.

Retain evidence consistently

Keep signed records, audit logs, and certificate status data together for the full retention period required by your policy or regulation. For HIPAA-covered records, retain signed documents for 6 years from the later of creation or last effective date.

Test verification and export

Test revocation checks, timestamps, and export procedures before rollout. Confirm that your team can retrieve a complete signing record, including identity details and document history, without relying on manual reconstruction after a dispute or audit.

FAQ and troubleshooting

These answers focus on setup limits, compliance requirements, and evidence issues that affect PKI-backed signing in signNow.

signNow Business includes legally binding eSignatures, audit trails, templates, mobile apps, and compliance support. If you need HIPAA workflows, confirm a BAA and use the right account controls before sending PHI.

HIPAA use requires a signed BAA and controls that protect PHI. signNow’s compliance posture includes HIPAA support, but the covered entity must still configure access, retention, and audit controls correctly under 45 CFR 164.312.

For 21 CFR Part 11 workflows, use unique user IDs, two-component authentication, secure audit trails, and documented validation. signNow’s regulated-use features should be matched to your validation and record-retention procedures.

If a certificate appears invalid, check revocation status, certificate expiration, and the trust chain. PKI verification depends on current OCSP or CRL data, so a stale revocation response can block validation.

If a signer disputes intent, export the audit trail and completed PDF. ESIGN and UETA rely on attribution and intent, so timestamps, delivery records, and signer actions matter more than the signature image.

The Business plan is priced at $8/user/mo with annual billing, while higher tiers add bulk send, advanced authentication, and integrations. If you need SSO or full API access, review the Enterprise or Site License options.

signNow	DocuSign	Adobe Sign	PandaDoc
ESIGN and UETA	Yes	Yes	Yes
Audit trail	Yes	Yes	Yes
HIPAA support	Yes	Yes	Yes
Envelope cap	No cap	100/year	Not verified

Setup day:

Create the workflow, assign users, and confirm certificate settings.

First send:

Send the first document after testing identity and audit logging.

Team onboarding:

Train reviewers and signers during the first week.

Free trial:

7-day free trial, no credit card required.

HIPAA retention:

6 years from creation or last effective date, per 45 CFR 164.530(j)(2).

Part 11 records:

Maintain secure audit trails and validation records for regulated use.

UETA coverage:

49 states, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands have adopted UETA.

Annual billing:

Business plan pricing is $8/user/month billed annually.

Risks of improper PKI use

Weak attribution

Document may be harder to enforce.

Missing audit trail

Signature can be challenged in court.

No revocation check

Certificate status may be disputed.

No BAA

PHI handling may violate HIPAA.

Poor validation

Records may fail Part 11 review.

Signer authentication:

Verify the signer with the configured authentication method.

Timestamp capture:

Capture the event time in UTC and ISO 8601 format.

Document hashing:

Hash the document before and after signing.

Tamper sealing:

Apply a tamper-evident seal to the completed file.

Record linkage:

Store the audit trail with the signed PDF.

Audit export:

Export the full history for review or dispute support.

	signNow	DocuSign	Adobe Sign	PandaDoc	HelloSign
Starting price	$8/user/mo	$15/user/mo	$14/user/mo	$19/user/mo	$15/user/mo
Free trial	7 days	Not verified	Not verified	Not verified	Not verified
Bulk send	Yes	Not verified	Not verified	Not verified	Not verified
Audit trail	Yes	Yes	Yes	Yes	Yes
HIPAA compliance	BAA required	BAA available	BAA available	Not verified	Not verified

28M+Documents signed

13+Years in business

4.6/5Average G2 rating