What is kms

Last updated: April 1, 2026

Quick Answer: KMS typically refers to AWS Key Management Service, Amazon's cloud service for managing cryptographic encryption keys. It enables users to create, import, and control encryption keys used to protect data across AWS services and custom applications.

Key Facts

Understanding AWS KMS

AWS Key Management Service (KMS) is a cloud-based service that simplifies the creation, management, and use of cryptographic keys. Encryption is a critical security practice, and KMS provides a secure, easy way to generate and control the encryption keys that protect sensitive data across AWS infrastructure and applications. Rather than managing encryption keys manually, organizations use KMS to delegate this responsibility to AWS's secure, certified infrastructure.

Core Features

KMS provides several essential features for key management: key creation and generation in AWS-managed hardware security modules, automatic key rotation on customizable schedules, detailed audit logging through AWS CloudTrail showing all key usage, and fine-grained access control using AWS Identity and Access Management (IAM) policies. Users can create customer-managed keys for complete control or use AWS-managed keys for simplified management. The service supports both symmetric and asymmetric keys, providing flexibility for various encryption scenarios.

Integration with AWS Services

One of KMS's greatest strengths is its seamless integration with other AWS services. Services like Amazon S3 (object storage), Amazon RDS (relational databases), Amazon EBS (block storage), AWS Lambda (serverless computing), and many others can automatically encrypt data using KMS keys. This integration simplifies security architecture by allowing organizations to implement encryption without managing separate key infrastructure for each service.

Security and Compliance

KMS operates on hardware security modules (HSMs) certified at FIPS 140-2 Level 2 or higher, ensuring cryptographic standards compliance. Keys stored in KMS never leave AWS infrastructure and cannot be exported, providing maximum security assurance. The service supports compliance with regulatory requirements including HIPAA (healthcare), PCI DSS (payment processing), and various government standards. CloudTrail integration provides detailed audit logs documenting all key access and usage, essential for compliance demonstrations.

Key Concepts

Important KMS concepts include customer-managed keys (full control over creation, rotation, and permissions), AWS-managed keys (automatic rotation, simpler management), and key material (the actual cryptographic material). KMS uses a key hierarchy where data keys are encrypted by master keys, enabling efficient bulk encryption. Users define key policies controlling who can use keys and for what purposes, supporting principle-of-least-privilege security architectures.

Related Questions

How does KMS differ from storing encryption keys locally?

KMS provides centralized, audited key management with hardware security module protection, automatic rotation, and compliance certifications. Local key storage requires manual management, provides no audit trails, and lacks the security certifications that regulated industries often require.

Can I export keys from AWS KMS?

No, keys stored in AWS KMS cannot be exported. This design principle ensures keys remain within AWS's secure infrastructure and helps meet compliance requirements. You can use keys to encrypt/decrypt data, but the key material itself stays protected within KMS.

How much does AWS KMS cost?

AWS KMS charges per key per month for key storage and per 10,000 API requests for key operations. Costs vary by region and key type. AWS offers a free tier including 20 requests/month, making it economical for small-scale applications.

Sources

  1. Wikipedia - Key Management Service CC-BY-SA-4.0
  2. AWS Key Management Service Organization