| 1 | package sheets |
| 2 | |
| 3 | import ( |
| 4 | "encoding/base64" |
| 5 | "errors" |
| 6 | "fmt" |
| 7 | "os" |
| 8 | "strings" |
| 9 | |
| 10 | "amadan.net/oficina/sheets/internal/sheets/seal" |
| 11 | ) |
| 12 | |
| 13 | // dekBytes is the DEK's required length. seal.New enforces it too; this |
| 14 | // check exists so the refusal names SHEETS_DEK and the length an |
| 15 | // operator has to produce, rather than surfacing a framework message |
| 16 | // about a byte slice. |
| 17 | const dekBytes = 32 |
| 18 | |
| 19 | // LoadSealer reads the data encryption key from platform config and |
| 20 | // builds the app's one Sealer. |
| 21 | // |
| 22 | // The DEK arrives as platform config (`carlos secrets`), never stored in |
| 23 | // the database — spec §2.1. A missing one is a hard refusal rather than |
| 24 | // a generated key: an instance that invents a DEK at boot seals this |
| 25 | // run's cells with a key the next run will not have, which reads as data |
| 26 | // loss and cannot be undone. Every other boot refusal in this app has |
| 27 | // the same shape, and for the same reason: continuing would produce an |
| 28 | // instance that answers /healthz perfectly well and then fails on the |
| 29 | // first cell anybody types. |
| 30 | // |
| 31 | // No error here ever includes the value read from the environment. It is |
| 32 | // a live key, and `carlos logs` is platform-held storage we cannot grep |
| 33 | // or redact (AGENTS.md / Mechanical rules). |
| 34 | func LoadSealer() (*seal.Sealer, error) { |
| 35 | raw := strings.TrimSpace(os.Getenv("SHEETS_DEK")) |
| 36 | if raw == "" { |
| 37 | return nil, errors.New( |
| 38 | "sealing is not configured: SHEETS_DEK not set. " + |
| 39 | "Generate one with `head -c 32 /dev/urandom | base64` and set it with " + |
| 40 | "`carlos secrets set --app sheets SHEETS_DEK=...`") |
| 41 | } |
| 42 | dek, err := base64.StdEncoding.DecodeString(raw) |
| 43 | if err != nil { |
| 44 | // The decode error is deliberately dropped rather than wrapped: |
| 45 | // base64.CorruptInputError renders as an offset, which is a |
| 46 | // (small) fact about the key's bytes. The variable name is the |
| 47 | // only thing an operator needs here. |
| 48 | return nil, errors.New("sealing is not configured: SHEETS_DEK is not valid base64") |
| 49 | } |
| 50 | if len(dek) != dekBytes { |
| 51 | return nil, fmt.Errorf( |
| 52 | "sealing is not configured: SHEETS_DEK decodes to %d bytes, want %d", |
| 53 | len(dek), dekBytes) |
| 54 | } |
| 55 | s, err := seal.New(dek) |
| 56 | if err != nil { |
| 57 | return nil, fmt.Errorf("sealing is not configured: %w", err) |
| 58 | } |
| 59 | return s, nil |
| 60 | } |
| 61 | |
amadan