ProofedMesh/services/dummy-sink/internal/canonical/canonical.go
CTO (Paperclip) b45ad34169
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dummy-sink: Phase-1 mock sink (sink:dummy-sink) (DEV-611)
Trivial Senken-Adapter per §7 of architecture V1.1. Accepts
{decision_id, payload_hash, payload, approval_ref, transform_ref}
on POST /api/v1/sink/dummy/deliver; calls verification-service's
/api/v1/verify/chain and branches:

- valid=true → atomic .tmp+rename write of payload to
  /data/dummy-sink/<decision_id>.json, builds a
  basicstack.de/attestations/handover/v1 statement, signs via
  signing-service with the double identity flow (Pocket-ID bearer
  + projected SA token), submits DSSE envelope to the TLog and
  returns 201 {handover_ref, log_index}.
- valid=false & replay=true → 409.
- valid=false → 403 {reasons:[…]}.

Replay protection lives in verification-service per the parent plan;
dummy-sink keeps no local replay store. The payload_hash field is
verified against both the raw and canonical form so a verifier can
reproduce either hash.

Tests use httptest-backed fakes for verify / sign / tlog and cover
the DEV-611 acceptance criteria plus the bad-request shapes:
- happy path writes the file, calls signer with the handover
  statement, submits the envelope to the TLog
- 403 keeps the disk and never calls signer/tlog
- replay returns 409 without re-signing
- payload_hash mismatch rejects before verify
- malformed bodies return 400
- verify unavailable → 502, signing denied → 403

Co-Authored-By: Paperclip <noreply@paperclip.ing>
2026-10-25 20:20:40 +00:00

103 lines
2.3 KiB
Go

// Package canonical implements the deterministic JSON serialisation
// (sorted object keys) dummy-sink uses when it computes payload / subject
// digests that MUST reproduce byte-for-byte on the verifier side.
//
// MUST stay compatible with:
// - services/approval-service/internal/canonical/canonical.go
// - services/signing-service/internal/canonical/canonical.go
// - services/testagent-transform/internal/canonical/canonical.go
package canonical
import (
"bytes"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"fmt"
"sort"
)
// SHA256Hex returns the hex-encoded SHA-256 of b.
func SHA256Hex(b []byte) string {
sum := sha256.Sum256(b)
return hex.EncodeToString(sum[:])
}
// Marshal returns the canonical JSON encoding of v (sorted object keys).
func Marshal(v any) ([]byte, error) {
first, err := json.Marshal(v)
if err != nil {
return nil, err
}
var any_ any
if err := json.Unmarshal(first, &any_); err != nil {
return nil, err
}
var buf bytes.Buffer
if err := writeSorted(&buf, any_); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
// Hash returns the sha256:<hex> content hash of v's canonical JSON along
// with the raw canonical bytes.
func Hash(v any) (string, []byte, error) {
raw, err := Marshal(v)
if err != nil {
return "", nil, err
}
return "sha256:" + SHA256Hex(raw), raw, nil
}
func writeSorted(buf *bytes.Buffer, v any) error {
switch x := v.(type) {
case nil:
buf.WriteString("null")
case bool:
if x {
buf.WriteString("true")
} else {
buf.WriteString("false")
}
case float64:
b, _ := json.Marshal(x)
buf.Write(b)
case string:
b, _ := json.Marshal(x)
buf.Write(b)
case []any:
buf.WriteByte('[')
for i, el := range x {
if i > 0 {
buf.WriteByte(',')
}
if err := writeSorted(buf, el); err != nil {
return err
}
}
buf.WriteByte(']')
case map[string]any:
keys := make([]string, 0, len(x))
for k := range x {
keys = append(keys, k)
}
sort.Strings(keys)
buf.WriteByte('{')
for i, k := range keys {
if i > 0 {
buf.WriteByte(',')
}
kb, _ := json.Marshal(k)
buf.Write(kb)
buf.WriteByte(':')
if err := writeSorted(buf, x[k]); err != nil {
return err
}
}
buf.WriteByte('}')
default:
return fmt.Errorf("canonical.writeSorted: unsupported type %T", v)
}
return nil
}