Security

Building a Private PKI with AWS Private CA - Automated Certificate Issuance and Rotation

Build a private certificate authority and automatically issue mTLS certificates for internal service-to-service communication. Learn about certificate lifecycle management and CRL design.

約 3 分で読めます

Overview of Private CA

Private CA is a managed certificate authority service that automates the issuance and management of private certificates. While ACM (AWS Certificate Manager) issues public certificates for free, Private CA issues private certificates for use within an organization. It is used for use cases that public certificates cannot address, such as mTLS between microservices, VPN client authentication, and IoT device authentication.

Certificate Issuance and mTLS

Using certificates issued by Private CA for mTLS between services provides both communication encryption and client authentication. Using short-lived certificates (valid for hours to days) eliminates the need to manage Certificate Revocation Lists (CRLs). Because the certificate validity period is short, the time window for exploiting a compromised certificate is extremely small. Integration with ACM enables automatic deployment of private certificates to ALBs, achieving HTTPS for internal ALBs.

Certificate Templates and Automation

Private CA issues purpose-specific certificates using certificate templates for server certificates, client certificates, code signing certificates, and more. ACM integration enables automatic deployment and renewal of Private CA-issued certificates to ALBs and API Gateway. Short-lived certificates (valid for 7 days or less) simplify CRL management by eliminating the need for certificate revocation processing. An OCSP (Online Certificate Status Protocol) responder configuration can verify certificate validity in real time. CA creation and certificate issuance can be automated with CloudFormation or Terraform, managing PKI infrastructure as IaC. For a systematic guide to certificate management from basics to advanced topics, see related books on Amazon.

Private CA Pricing

Private CA costs approximately $400 per month per CA, with additional charges based on the number of certificates issued. The first 1,000 certificates cost $0.75 each, and up to 10,000 cost $0.35 each. Short-lived certificate mode reduces the monthly CA fee to approximately $50, improving cost efficiency in microservices environments that issue large volumes of short-lived certificates. A CA hierarchy (root CA -> subordinate CA) where the root CA is kept offline and only the subordinate CA is operational is a security best practice.

Summary

Private CA is a service that provides managed issuance and management of private certificates within an organization. Short-lived certificates (7 days or less) simplify CRL management, and ACM integration automates certificate deployment and renewal. mTLS enables mutual authentication between services, and a CA hierarchy (root CA + subordinate CA) builds a PKI that follows security best practices.

Related Services

AWS Private Certificate AuthorityA managed certificate authority service for issuing and managing private certificatesAWS Certificate ManagerA service that automates provisioning, management, and deployment of SSL/TLS certificatesAWS IAMAn authentication and authorization service for securely managing access to AWS resources

Related Articles

AWS Secrets Manager - Automatic Rotation and Application IntegrationAutomatically rotate RDS and Aurora passwords with Lambda functions and seamlessly retrieve secrets from applications using the SDK caching library. Also covers when to use Parameter Store instead.Automating SSL/TLS Certificate Management with AWS Certificate Manager - From Issuance to RotationLearn how ACM handles free public certificate issuance, DNS validation, automatic renewal, and deployment to ALB and CloudFront.Dedicated Key Management with AWS CloudHSM - FIPS 140-2 Level 3 Compliant EncryptionAchieve FIPS 140-2 Level 3 compliant key management with dedicated HSM instances. Learn when to choose CloudHSM over KMS and how to integrate both through KMS custom key stores.

More on This Topic

Detecting Excessive Permissions with IAM Access Analyzer - External Access and Unused Permission AnalysisDetect unused permissions on IAM roles using CloudTrail-based analysis and auto-generate least-privilege policies. This guide covers external access detection and integrating custom policy checks into your CI/CD pipeline.Automating SSL/TLS Certificate Management with AWS Certificate Manager - From Issuance to RotationLearn how ACM handles free public certificate issuance, DNS validation, automatic renewal, and deployment to ALB and CloudFront.Retrieving Compliance Reports with AWS Artifact - Audit Response and Agreement ManagementLearn how to retrieve SOC, PCI DSS, and ISO audit reports on demand and apply BAA and GDPR DPA agreements across your entire AWS Organizations structure.Automating Audits - Continuously Collecting Compliance Evidence with AWS Audit ManagerLearn how to automate audit evidence collection with AWS Audit Manager. This guide covers automated assessments based on frameworks such as SOC 2, PCI DSS, and GDPR, centralized evidence management, and audit report generation.The Hidden Structure of AWS Account IDs' 12 Digits - Why 12 Digits, and What Can You Infer?A trivia-style exploration of why AWS account IDs are 12-digit numbers, the design intent embedded in the ARN structure, and the security considerations around what can be inferred from an account ID.Why the AWS Account Root User Is Dangerous - The Design Philosophy of Privilege Separation and Practical LockdownWe explain why the AWS root user holds privileges that cannot be restricted by IAM, list the operations only the root user can perform, cover MFA setup methods, and describe the lockdown strategy using Organizations' centralized root access management.Certificate Management and HTTPS - Automated TLS Certificate Operations with AWS Certificate ManagerLearn about TLS/SSL certificate issuance, automatic renewal, and deployment using AWS Certificate Manager (ACM). Covers integration with CloudFront, ALB, and API Gateway, DNS validation, and Private CA usage.Dedicated Key Management with AWS CloudHSM - FIPS 140-2 Level 3 Compliant EncryptionAchieve FIPS 140-2 Level 3 compliant key management with dedicated HSM instances. Learn when to choose CloudHSM over KMS and how to integrate both through KMS custom key stores.

Similar Articles and Services

AWS Private Certificate AuthorityA managed certificate authority that issues and manages private certificates for internal organizational useCertificate Management and HTTPS - Automated TLS Certificate Operations with AWS Certificate ManagerLearn about TLS/SSL certificate issuance, automatic renewal, and deployment using AWS Certificate Manager (ACM). Covers integration with CloudFront, ALB, and API Gateway, DNS validation, and Private CA usage.Automating SSL/TLS Certificate Management with AWS Certificate Manager - From Issuance to RotationLearn how ACM handles free public certificate issuance, DNS validation, automatic renewal, and deployment to ALB and CloudFront.AWS Certificate ManagerA service that provisions, manages, and auto-renews SSL/TLS certificates, enabling free HTTPS on CloudFront and ALB