Ruby McKenzie
The growing adoption of electronic signatures has made APIs (Application Programming Interfaces) an essential tool for integrating eSign solutions into business workflows. However, with increased API usage comes the heightened risk of data breaches and unauthorized access. A 2024 IBM Security report found that API security incidents accounted for 30% of all cloud-based breaches—a number that is expected to rise in 2025 as digital transactions increase.
Inadequate security in eSign APIs can expose sensitive contracts, financial agreements, and confidential business documents to cybercriminals. This blog will discuss why security matters in eSign APIs, the biggest risks, and the best practices to prevent security breaches.
Why Security Matters in eSign APIs
eSignature API handles sensitive data, making them a prime target for hackers. Here’s why securing them is crucial:
- Legal and Compliance Risks: Regulations like eIDAS (Europe), GDPR, the ESIGN Act (US), and SOC 2 mandate strict security measures for digital transactions.
- Financial and Reputation Damage: The average cost of a data breach reached $4.45 million in 2023, according to IBM Security. A poorly secured eSign API can expose businesses to lawsuits, fines, and reputational harm.
- Increasing Cyber Threats: With APIs being the backbone of modern software applications, they are frequently exploited for unauthorized access. API-related breaches surged by 200% in 2024, as per Cybersecurity Ventures.
“As companies rely more on APIs for critical transactions, ensuring robust security measures isn’t optional—it’s a necessity.” – John Reese, CTO at SecureSign Technologies
Common Security Risks in eSign APIs
To build a secure eSign integration, businesses must be aware of the following risks:
1. Unauthorized Access & Credential Leaks
Weak authentication methods allow attackers to exploit API keys, steal credentials, and gain unauthorized access to sensitive documents.
2. Man-in-the-Middle (MITM) Attacks
If an eSign API transmits data over an unencrypted channel, attackers can intercept and manipulate the information.
3. Insufficient Encryption
Many breaches occur because data is either stored in plaintext or transmitted without proper encryption.
4. API Rate Limiting Exploits
Without proper rate limiting, an attacker can flood an eSign API with requests, leading to denial-of-service (DoS) attacks or data scraping.
5. Poor Webhook Security
Unverified webhook callbacks can allow unauthorized users to manipulate signed documents or gain unauthorized access.
Best Practices for Securing eSign APIs
1. Implement Strong Authentication & Authorization
- Use OAuth 2.0 and JWT (JSON Web Tokens) to ensure secure user authentication.
- Enforce Multi-Factor Authentication (MFA) for users accessing eSign APIs.
- Apply Role-Based Access Control (RBAC) to restrict document access.
2. Encrypt Data at Rest & in Transit
- Use TLS 1.2 or higher to encrypt all API communications.
- Store documents using AES-256 encryption, ensuring data security.
- Regularly rotate encryption keys to minimize security risks.
3. Secure API Keys & Access Tokens
- Never hardcode API keys in code repositories.
- Store secrets in AWS Secrets Manager, HashiCorp Vault, or Azure Key Vault.
- Use short-lived API tokens that expire after a set duration.
4. Implement Webhook Security Measures
- Verify webhook requests using HMAC (Hash-based Message Authentication Code) signatures.
- Use IP whitelisting to restrict webhook access.
- Rate-limit webhook requests to prevent abuse.
5. API Rate Limiting & DDoS Protection
- Use token-based rate limiting to control API request frequency.
- Implement WAFs (Web Application Firewalls) like Cloudflare or AWS WAF to detect and block threats.
- Monitor API traffic using SIEM (Security Information and Event Management) tools.
6. Maintain Audit Logs & Monitor API Activity
- Log every API request with IP, timestamp, and user details.
- Use real-time alerting to detect unusual API activity.
- Regularly audit logs for security anomalies.
Certinal eSign API: Secure and Scalable Digital Signing
Certinal’s eSignature API enables businesses to integrate secure and seamless digital signing capabilities into their existing systems. Designed for flexibility, the API supports a range of use cases, from simple contract approvals to complex multi-party workflows. With AES-256 encryption, OAuth-based authentication, and compliance with ISO 27001, SOC 2, and eIDAS, Certinal ensures that all transactions remain secure and legally binding. Additionally, its automation capabilities streamline document workflows, reducing manual intervention while maintaining efficiency and security.
Compliance & Regulatory Considerations
Many global regulations mandate secure eSign API implementations:
| Regulation | Requirement |
| eIDAS (Europe) | Secure identity verification & encryption |
| GDPR (EU) | Data protection & breach reporting |
| ESIGN Act (US) | Secure and legally binding digital signatures |
| SOC 2 & ISO 27001 | API security best practices & audit logging |
“Compliance is not just about meeting legal requirements; it’s about building trust with your customers.” – Sarah Williams, Cybersecurity Consultant
Case Study: How a Global Enterprise Prevented an API Breach
In 2024, a Fortune 500 financial services company faced an API security challenge. Their eSign API was vulnerable to unauthorized access due to weak authentication methods. Attackers attempted to exploit API keys embedded in front-end code.
Solution Implemented:
✅ Adopted OAuth 2.0 with JWT authentication to prevent unauthorized access.
✅ Enabled API key rotation policies to limit token exposure.
✅ Implemented IP whitelisting & rate limiting to block bot traffic.
Outcome:
The company prevented a potential $3M security breach and improved compliance with SOC 2 & GDPR standards.
Conclusion
Securing eSign APIs is critical for preventing data breaches and ensuring compliance. Businesses must implement strong authentication, encryption, and monitoring to protect sensitive transactions.
If you’re looking for a secure eSign API solution, Certinal eSign offers enterprise-grade security with end-to-end encryption, role-based access, and compliance with global regulations.
🔐 Ready to secure your digital agreements? Book a demo today!
