Chapter 11 — Security & Secrets

Day 1 — Secrets Manager and SSM Parameter Store

1. Concept Primer

Secrets Manager stores sensitive values (DB passwords, API keys) with built-in rotation support. Parameter Store (SSM) is a simpler key-value config store — cheaper and fine for non-rotating config, while Secrets Manager is the better fit for anything needing rotation or fine-grained access policies.

2. Hands-on Exercise

Store a secret and a plain parameter, then retrieve both back out.

3. Exact Commands

floci start && eval $(floci env)

aws secretsmanager create-secret \
  --name day1/db-password \
  --secret-string '{"username":"admin","password":"sup3rSecret!"}'

aws secretsmanager get-secret-value --secret-id day1/db-password \
  --query 'SecretString' --output text

aws ssm put-parameter \
  --name "/day1/app/log-level" \
  --value "INFO" \
  --type String

aws ssm get-parameter --name "/day1/app/log-level" --query 'Parameter.Value' --output text

4. Gotchas

• Secret names containing / are fine and common (used for logical namespacing), but double check quoting in your shell — unescaped slashes rarely break things, but unescaped special characters in the JSON secret string will.
• Rotation configuration (rotate-secret + a rotation Lambda) is a more advanced feature to verify current support depth for before relying on it — this chapter covers store/retrieve, not automated rotation.

5. Self-Check

Given a piece of config that changes constantly but isn't sensitive (like a feature flag), would Parameter Store or Secrets Manager be the more appropriate choice, and why?

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Day 2 — KMS Envelope Encryption

1. Concept Primer

KMS manages encryption keys without ever exposing the raw key material to you directly. Envelope encryption is the standard pattern: KMS encrypts a small data key, you use that data key locally to encrypt your actual (possibly large) payload, then store the encrypted data key alongside the encrypted payload.

2. Hands-on Exercise

Create a KMS key, generate a data key, and use it to encrypt/decrypt a short message locally.

3. Exact Commands

eval $(floci env)

KEY_ID=$(aws kms create-key --query 'KeyMetadata.KeyId' --output text)
echo "KMS Key: $KEY_ID"

# Direct encrypt/decrypt of a small payload
aws kms encrypt --key-id $KEY_ID --plaintext "hello secret" \
  --query 'CiphertextBlob' --output text > ciphertext.txt

aws kms decrypt --ciphertext-blob fileb://<(cat ciphertext.txt | base64 -d) \
  --query 'Plaintext' --output text | base64 -d

# Envelope pattern: generate a data key, keep the plaintext key only in memory/briefly
aws kms generate-data-key --key-id $KEY_ID --key-spec AES_256

4. Gotchas

• kms encrypt output is base64-encoded already; piping it through an extra base64 -d before decrypt (as shown) is necessary because the CLI writes text output, not raw bytes, to a file.
• generate-data-key returns both a Plaintext (usable immediately, must never be persisted) and a CiphertextBlob (safe to store) version of the same key — mixing these up is the single most common real-world KMS mistake.

5. Self-Check

Why is it safe to store the CiphertextBlob from generate-data-key right next to your encrypted data, but never safe to store the Plaintext version?