Encryption at rest

Cognimemo can encrypt memory bodies at rest with AES-256-GCM using a server-held master key. It's opt-in per bank, and completely transparent to your code — recall and reflect always return plaintext.

How it works

• Write: memory text and context are encrypted after embeddings are computed from plaintext, so semantic recall is unaffected. Ciphertext is self-describing (enc:v1:<nonce>:<ct>).
• Read: recall / reflect / list decrypt transparently. A bank can hold a mix of older plaintext and newer encrypted rows — every read still works (lazy migration).
• Key: a single operator-held master key, COGNIMEMO_API_ENCRYPTION_MASTER_KEY. When it's unset, encryption is a no-op everywhere.

Honest posture: this is encryption at rest, not end-to-end — Cognimemo holds the key. The guarantee is that memory bodies are unreadable at rest without it.

Turning it on

cm.enable_encryption("jane@acme.com")     # sets bank config encryption="managed"
# ...retain / recall exactly as before — you always get plaintext back...
cm.disable_encryption("jane@acme.com")    # stop encrypting NEW memories

await cm.enableEncryption("jane@acme.com");

Requires the operator to have set the master key on the server. Existing plaintext rows stay readable; new memories are stored encrypted.

Scope (v1)

Encrypted: memory_units.text and .context. Not yet covered: chunk/document original text and keyword-search lexemes. Entity names and mental-model descriptions remain plaintext so graph and search keep working.