| 1 | package hostevidence |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "crypto/ed25519" |
| 7 | "errors" |
| 8 | "strings" |
| 9 | |
| 10 | "github.com/carlosframework/platform/internal/release" |
| 11 | ) |
| 12 | |
| 13 | var ErrSignature = errors.New("hostevidence: invalid receipt signature") |
| 14 | |
| 15 | func message(key string, body []byte) ([]byte, error) { |
| 16 | parts := strings.Split(key, "/") |
| 17 | if len(parts) < 6 || parts[0] != "control" || parts[1] != "hosts" || |
| 18 | !((len(parts) == 7 && parts[3] == "evidence") || (len(parts) == 6 && parts[3] == "serving-evidence")) || |
| 19 | !strings.HasSuffix(key, ".json") || strings.ContainsAny(key, "\\\x00\r\n") { |
| 20 | return nil, ErrSignature |
| 21 | } |
| 22 | for _, part := range parts { |
| 23 | if part == "" || part == "." || part == ".." { |
| 24 | return nil, ErrSignature |
| 25 | } |
| 26 | } |
| 27 | out := append([]byte("carlos-host-stop-v1\x00"+key+"\x00"), body...) |
| 28 | return out, nil |
| 29 | } |
| 30 | func Verify(pub ed25519.PublicKey, key string, body, signature []byte) error { |
| 31 | wire, err := message(key, body) |
| 32 | if err != nil || len(pub) != ed25519.PublicKeySize || len(signature) != ed25519.SignatureSize || !ed25519.Verify(pub, wire, signature) { |
| 33 | return ErrSignature |
| 34 | } |
| 35 | return nil |
| 36 | } |
| 37 | func immutable(ctx context.Context, s release.Store, key string, body []byte) error { |
| 38 | if _, err := s.Put(ctx, key, body, ""); err == nil { |
| 39 | return nil |
| 40 | } else if !errors.Is(err, release.ErrCASConflict) { |
| 41 | return err |
| 42 | } |
| 43 | existing, _, err := s.Get(ctx, key) |
| 44 | if err != nil { |
| 45 | return err |
| 46 | } |
| 47 | if !bytes.Equal(existing, body) { |
| 48 | return ErrSignature |
| 49 | } |
| 50 | return nil |
| 51 | } |
| 52 | func Publish(ctx context.Context, s release.Store, private ed25519.PrivateKey, key string, body []byte) error { |
| 53 | wire, err := message(key, body) |
| 54 | if err != nil || s == nil || len(private) != ed25519.PrivateKeySize { |
| 55 | return ErrSignature |
| 56 | } |
| 57 | signature := ed25519.Sign(private, wire) |
| 58 | if err = immutable(ctx, s, key, body); err != nil { |
| 59 | return err |
| 60 | } |
| 61 | return immutable(ctx, s, key+".sig", signature) |
| 62 | } |
| 63 | |
amadan