S3 Encryption at Rest

~8 min read

Three ways to encrypt S3 data, differing in who manages the keys.

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Key points

  • SSE-S3: AWS-managed keys, automatic, free, the sensible default
  • SSE-KMS: KMS-managed keys, audit trail via CloudTrail, fine-grained access control, small per-request cost
  • SSE-C: customer-supplied key, AWS never stores it, full responsibility (and risk) on the customer
  • Choice depends on compliance/audit needs, not on data sensitivity alone — all three encrypt the data at rest