Encryption Controls
Explore common AWS encryption control failures such as KMS decrypt denials, ACM certificate mismatches, and Secrets Manager access errors. Understand how to diagnose issues, apply minimal policy fixes, and validate solutions without exposing sensitive data to maintain secure and reliable cloud operations.
Two failures land on the same afternoon and look completely unrelated at first glance. A production API starts returning 500, and the logs include a representative error like AccessDeniedException not authorized to perform kms:Decrypt on key arn:aws:kms:REGION:ACCOUNT_ID:key/KEY_ID. A different endpoint still returns 200, but clients intermittently fail TLS validation and report a symptom like certificate common name does not match api.example.com or certificate expired. Neither symptom mentions encryption by name, but that's exactly what both are.
Both are encryption control failures, and the real work is deciding where to look first and what evidence proves the fix without exposing sensitive material. The goal is to restore service by changing the right boundary, not by weakening encryption or copying secret values into logs.
KMS boundaries that block decrypt
A KMS failure shows up as an application failure because the dependent service can no longer unwrap the data key it needs to read ciphertext at rest. The trigger is usually a principal calling a service API, the service calls kms:Decrypt on the caller's behalf, and KMS returns an authorization decision that bubbles up as AccessDenied or an internal error in the calling service.
Two policy layers must line up for the decrypt path to work, and a mismatch produces different remediation actions. The key policy on the KMS key is the resource boundary that can block access even when IAM allows ...