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Go
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import ( "encoding/json" "fmt" "time"
"stream.place/streamplace/pkg/crypto/signers" "stream.place/streamplace/pkg/crypto/spkey" "stream.place/streamplace/pkg/muxl")
// uploadSigner is the per-upload ephemeral signing material. The private// key exists only for the lifetime of one ProcessVOD call: it signs// every segment of the upload, then the caller drops it — so once// processing finishes nobody can mint more signatures under DIDKey.type uploadSigner struct { // SignerInput carries the cert + PKCS#8 key PEM + manifest handed to // muxl-sign's sign-segment subcommand. SignerInput muxl.SignerInput // DIDKey is the did:key derived from the public half. It's recorded // on every place.stream.media.track for this upload so verifiers can // match the embedded C2PA signatures back to a key. DIDKey string}
// newUploadSigner generates a fresh secp256k1 keypair, self-signs an// ES256K cert for it, and bundles everything sign-segment needs. The// private key material lives only in the returned SignerInput; it's// never persisted.func newUploadSigner(processedAt time.Time) (*uploadSigner, error) { priv, pub, err := spkey.GenerateStreamKey() if err != nil { return nil, fmt.Errorf("generate signing key: %w", err) } signer, err := spkey.KeyToSigner(priv) if err != nil { return nil, fmt.Errorf("convert signing key: %w", err) } cert, err := signers.GenerateES256KCert(signer) if err != nil { return nil, fmt.Errorf("generate signing cert: %w", err) } keyPEM, err := signers.MarshalES256KPrivateKeyPEM(signer) if err != nil { return nil, fmt.Errorf("marshal signing key: %w", err) } manifest, err := buildSignManifest(processedAt) if err != nil { return nil, err } return &uploadSigner{ SignerInput: muxl.SignerInput{ CertPEM: cert, KeyPEM: keyPEM, TrackManifest: manifest, WrapperManifest: manifest, Alg: "es256k", }, DIDKey: pub.DIDKey(), }, nil}
// buildSignManifest produces the minimal C2PA manifest embedded in every// signed VOD segment: the standard c2pa.created/c2pa.published action// pair stamped with the processing time. muxl-sign applies it to each// per-track canonical segment.func buildSignManifest(processedAt time.Time) ([]byte, error) { ts := processedAt.UTC().Format(time.RFC3339) mani := map[string]any{ "title": fmt.Sprintf("Streamplace VOD processed at %s", ts), "assertions": []map[string]any{ { "label": "c2pa.actions", "data": map[string]any{ "actions": []map[string]any{ {"action": "c2pa.created", "when": ts}, {"action": "c2pa.published", "when": ts}, }, }, }, }, } body, err := json.Marshal(mani) if err != nil { return nil, fmt.Errorf("marshal sign manifest: %w", err) } return body, nil}