Mobile QES: Signing Documents from Your Smartphone

Why Mobile QES Matters for Modern Business

The shift to mobile qualified electronic signatures isn’t just about convenience—it’s about fundamentally changing how business operates in an increasingly mobile-first world.

The Reality of Modern Work

According to recent studies, professionals check their smartphones over 100 times per day and spend more time on mobile devices than desktop computers. Yet many business processes remain anchored to desktops, creating friction when you’re away from your desk.

Mobile QES eliminates this friction by bringing the highest level of legally binding electronic signatures to the device you always carry: your smartphone.

Business Impact: Real Numbers

• Time savings: Sign documents in 30-60 seconds instead of hours waiting to access a desktop
• Faster closing: Reduce contract turnaround time from days to minutes when all parties can sign immediately
• Increased flexibility: Work from anywhere without being tied to office equipment
• Better responsiveness: Respond to time-sensitive opportunities without delays

Legal Status: Fully Compliant QES

Mobile qualified electronic signatures aren’t a compromise on legal validity. Under eIDAS Regulation Article 25(2), qualified electronic signatures created on smartphones have the exact same legal status as those created on desktop computers—they’re legally equivalent to handwritten signatures across all 27 EU member states.

The key requirement is that signatures are created using qualified certificates from Qualified Trust Service Providers (QTSPs) through Qualified Signature Creation Devices (QSCDs). Modern smartphones meet QSCD requirements through secure enclaves that protect cryptographic keys, making your phone a legally compliant signing device.

Three Ways to Create Mobile QES

Three main approaches enable qualified electronic signatures from smartphones, each with different characteristics suited to different use cases. Understanding these options helps you choose the right method for your needs.

Step-by-Step: Signing with Mobile Apps (itsme & Evrotrust)

Mobile app-based QES methods require one-time setup, after which signing becomes nearly instantaneous. Here’s how to get started and create your first mobile qualified signature.

Method 1: itsme® (Belgium & 23 Other European Countries)

Method 2: Evrotrust (58 Countries Including EU & International)

Comparison: itsme vs. Evrotrust

Step-by-Step: App-Free Mobile Signing (Adacom)

Some users prefer not to download apps or complete pre-registration. Adacom’s approach enables qualified signatures directly through your mobile browser with identity verification happening during each signature.

Method 3: Adacom (68 Countries, No App Required)

When to Choose App-Free Signing

• Infrequent signing: Sign 1-2 documents per year and don’t want another app
• Wider geographic coverage: Need support for countries not covered by itsme or Evrotrust
• Immediate need: Must sign now without time for app setup
• Device constraints: Older smartphone without NFC or latest OS
• Privacy preference: Prefer not to maintain persistent signing credentials on device

Security Considerations for Mobile QES

Creating legally binding signatures on smartphones raises understandable security questions. Here’s how mobile QES maintains the same security standards as desktop signing.

Device-Level Security

Modern smartphones include secure enclaves—isolated hardware components that store cryptographic keys and perform security-critical operations. Your private signing keys:

• Never leave the secure enclave
• Cannot be extracted even if someone gains access to your phone
• Require biometric or PIN authentication for every use
• Are automatically protected by device encryption

Network Security

All communication between your smartphone and QTSPs uses:

• TLS/SSL encryption: Industry-standard transport security
• Certificate pinning: Prevents man-in-the-middle attacks
• Mutual authentication: Both parties verify each other’s identity

Best Practices for Secure Mobile Signing

Do:

• ✓ Keep your smartphone OS and signing apps updated
• ✓ Use strong biometric authentication (fingerprint/Face ID) where available
• ✓ Set a secure PIN/password as fallback
• ✓ Only sign on secure WiFi or cellular networks
• ✓ Review documents carefully before signing, even on small screens
• ✓ Enable remote device wipe capability in case phone is lost

Don’t:

• ✗ Share your phone or signing credentials with others
• ✗ Sign on public WiFi without VPN protection
• ✗ Install signing apps from unofficial sources
• ✗ Disable device security features for convenience
• ✗ Sign documents you haven’t thoroughly reviewed

Real-World Mobile QES Use Cases

Mobile qualified signatures transform workflows across industries. Here are practical scenarios where mobile QES delivers immediate value.

Use Case 1: HR and Employee Onboarding

Use Case 2: Sales Contracts and Time-Sensitive Deals

A sales representative meets a client at a trade show. The client wants to proceed immediately, but the contract requires qualified signatures from both the sales rep and their manager (who’s traveling).

Mobile QES solution: Sales rep generates contract on laptop, sends for signatures via QES-Sign. Both sales rep and manager sign on their smartphones within minutes. Client uses Adacom (no app) to complete verification and sign. Deal closed before leaving the trade show.

Use Case 3: Legal Documents and Power of Attorney

A Belgian citizen needs to sign power of attorney documents for a real estate transaction in Spain but is currently on vacation in Greece.

Mobile QES solution: Notary sends documents requiring QES. The signer uses Evrotrust on their smartphone to apply qualified signatures while on vacation. Documents are legally valid in Spain under eIDAS cross-border recognition. Transaction proceeds on schedule.

Use Case 4: Government Filings (INPI France)

An entrepreneur discovers an error in their company registration and needs to file a correction with France’s INPI before a deadline—but they’re traveling for business.

Mobile QES solution: Prepare correction documents, sign with any QES method (itsme, Evrotrust, or Adacom) directly from smartphone. Submit to INPI. Qualified signature meets legal requirements; correction filed on time despite being remote.

Choosing Your Mobile QES Method

Which mobile signing approach fits your situation? Consider these factors:

Decision Framework

Choose itsme® if:

• You’re based in Belgium, Netherlands, Luxembourg, or France
• You sign documents regularly (weekly or monthly)
• You have a recent smartphone with NFC capability
• You value the fastest possible signing once registered
• Your counterparties are primarily in Western/Central Europe

Choose Evrotrust if:

• You need broader geographic coverage (58 countries)
• You sign documents regularly and want app-based convenience
• You work with partners in Eastern Europe or the Balkans
• You prefer fully remote registration without NFC requirements
• You need international coverage beyond Western Europe

Choose Adacom if:

• You sign documents infrequently (quarterly, annually)
• You prefer not to download additional apps
• You need the widest possible coverage (68 countries including Asia, Americas)
• You want to sign immediately without pre-registration
• You work with truly global partners requiring signatures from any country

Key Takeaways

• Mobile QES is legally equivalent to desktop QES: Qualified electronic signatures created on smartphones have the exact same legal status as those created on computers—full equivalence to handwritten signatures across all 27 EU member states under eIDAS Article 25(2).
• Three approaches serve different needs: App-based methods (itsme, Evrotrust) provide instant signing after one-time registration, while app-free approaches (Adacom) enable immediate signatures without pre-setup—choose based on signing frequency and preferences.
• Setup takes minutes, signing takes seconds: Initial registration for app-based methods requires 5-15 minutes, after which every subsequent signature takes just 30-60 seconds. App-free methods complete verification and signing in 2-5 minutes total.
• Security meets or exceeds desktop signing: Smartphones’ secure enclaves, biometric authentication, and encrypted communications provide the same security standards as desktop signing, with the convenience of signing from anywhere at any time.
• Real business impact beyond convenience: Mobile QES reduces contract turnaround from days to minutes, enables remote work without process delays, improves responsiveness to time-sensitive opportunities, and eliminates the need to be at a specific location to sign critical documents.
• Geographic coverage varies significantly: itsme covers 24 countries (Western/Central Europe), Evrotrust covers 58 countries (EU + international), and Adacom covers 68 countries (truly global)—verify your signers’ locations when selecting methods.

Frequently Asked Questions

Is a mobile qualified electronic signature as legally valid as a desktop signature?

Yes, absolutely. Under eIDAS Regulation, qualified electronic signatures have the same legal status regardless of the device used to create them. A QES created on your smartphone is legally equivalent to a handwritten signature throughout the EU, just like a desktop-created QES.

Do I need a specific type of smartphone?

Most modern smartphones work with mobile QES solutions. For app-based methods: itsme requires iOS 13+ or Android 6.0+ with NFC; Evrotrust requires iOS 12.0+ or Android 5.0+ (no NFC needed). Adacom works in mobile browsers without app requirements. Devices from the last 4-5 years typically meet all requirements.

What happens if I lose my phone after registering?

Immediately contact your QTSP to revoke your qualified certificate. For itsme and Evrotrust, you can also manage access through account settings on another device. Signatures created before revocation remain valid. You can then re-register on a new phone. Most providers allow certificate transfer or re-issuance at no additional cost.

Can I sign documents when I have no internet connection?

No. Creating qualified electronic signatures requires real-time communication with QTSPs to generate signatures, apply timestamps, and verify certificate validity. You need either WiFi or cellular data connection. However, signatures typically complete in seconds, so brief connections suffice.

How much does mobile QES cost?

Pricing varies by method and platform. Through QES-Sign’s pay-per-use model, qualified signatures start at €5 per signature with no subscription required. Some providers charge per-signature fees, others require subscriptions. For occasional signing (5-10 documents monthly), pay-per-use often proves more economical than subscriptions.

Is mobile signing secure on public WiFi?

While all communications are encrypted, public WiFi presents additional risks. If you must sign on public WiFi, use a VPN for extra protection. Cellular data is generally more secure than public WiFi. Best practice: use trusted WiFi networks or cellular connections for signing important documents.

Can multiple people in my company use mobile QES?

Yes. Each person needs their own qualified certificate issued in their individual name. For app-based methods, each employee registers separately on their personal smartphone. Organizations can centralize document management and signature requests while individuals create signatures on their own devices.

Which method is fastest for signing?

After initial setup, app-based methods (itsme, Evrotrust) are fastest at 30-60 seconds per signature. Adacom takes 2-5 minutes per signature including identity verification. However, Adacom requires no setup time, so for your very first signature, it may actually be fastest. Choose based on whether you’ll sign once or repeatedly.

Conclusion

Mobile qualified electronic signatures represent more than technological convenience—they fundamentally change the relationship between business processes and physical location. When creating legally binding signatures no longer requires being at a specific desk with specific equipment, work becomes truly mobile in ways that seemed impossible just a decade ago.

The transformation is particularly powerful for small and medium businesses that previously couldn’t justify expensive desktop-bound signature infrastructure but now can access the highest level of legal signatures through devices their employees already carry. Sophie signing employment contracts while commuting, sales representatives closing deals at trade shows, and entrepreneurs filing government documents while traveling aren’t edge cases—they’re the new normal.

Whether you choose app-based methods for frequent signing convenience or app-free approaches for occasional use without setup hassle, the result is the same: qualified electronic signatures with full legal equivalence to handwritten signatures, created wherever you happen to be, whenever you happen to need them. The only question is which method best fits your specific situation—and now you have the knowledge to make that choice confidently.

The future of business signatures isn’t arriving—it’s already in your pocket.