fed-sx-m1: Step 2c — envelope:verify_signature/2 (time-aware key lookup + HMAC stand-in) + 11 tests

next/kernel/envelope.erl

@@ -1,5 +1,5 @@
 -module(envelope).
--export([validate_shape/1, get_field/2, canonical_bytes/1]).
+-export([validate_shape/1, get_field/2, canonical_bytes/1, verify_signature/2]).
 
 %% Activity envelope per design §3.1.
 %%
@@ -83,3 +83,95 @@ insert_pair({K1, V1}, [{K2, V2} | Rest]) ->
         true  -> [{K1, V1}, {K2, V2} | Rest];
         false -> [{K2, V2} | insert_pair({K1, V1}, Rest)]
     end.
+
+%% verify_signature/2 — time-aware sig verification per design §9.6.
+%%
+%% Activity carries a `signature` proplist with `key_id`, `algorithm`,
+%% `value`. ActorState carries `public_keys` — a list of key proplists
+%% with `id`, `created`, optionally `superseded_at`, and `value` (the
+%% key material).
+%%
+%% A key is active at time T iff `created =< T` AND
+%% (no `superseded_at` OR T < `superseded_at`). Verification picks the
+%% first matching active key whose `id == signature.key_id` at the
+%% activity's `published` timestamp, then recomputes the MAC
+%% `crypto:hash(sha256, <<KeyMaterial/binary, CanonicalBytes/binary>>)`
+%% and compares it to `signature.value`.
+%%
+%% Returns ok | {error, Reason}. Reasons:
+%%   no_signature | no_key_id | no_published | no_keys |
+%%   no_active_key | bad_signature
+%%
+%% Real RSA-SHA256 / Ed25519 verification is deferred to milestone 2:
+%% Phase 8 only ships `crypto:hash/2`, so we stand in with an HMAC-shaped
+%% MAC that exercises the same key-lookup and canonical-bytes pipeline.
+
+verify_signature(Activity, ActorState) ->
+    case get_field(signature, Activity) of
+        not_found -> {error, no_signature};
+        {ok, Sig} ->
+            case get_field(key_id, Sig) of
+                not_found -> {error, no_key_id};
+                {ok, KeyId} ->
+                    case get_field(published, Activity) of
+                        not_found -> {error, no_published};
+                        {ok, Published} ->
+                            verify_with_keys(Activity, Sig, KeyId,
+                                             Published, ActorState)
+                    end
+            end
+    end.
+
+verify_with_keys(Activity, Sig, KeyId, Published, ActorState) ->
+    case get_field(public_keys, ActorState) of
+        not_found -> {error, no_keys};
+        {ok, Keys} ->
+            case find_active_key(KeyId, Published, Keys) of
+                not_found -> {error, no_active_key};
+                {ok, Key} -> verify_mac(Activity, Sig, Key)
+            end
+    end.
+
+find_active_key(_, _, []) -> not_found;
+find_active_key(KeyId, Now, [Key | Rest]) ->
+    case is_matching_active_key(Key, KeyId, Now) of
+        true -> {ok, Key};
+        false -> find_active_key(KeyId, Now, Rest)
+    end.
+
+is_matching_active_key(Key, WantId, Now) ->
+    case get_field(id, Key) of
+        {ok, WantId} -> is_active_at(Key, Now);
+        _ -> false
+    end.
+
+is_active_at(Key, Now) ->
+    case get_field(created, Key) of
+        not_found -> false;
+        {ok, Created} ->
+            case Now >= Created of
+                false -> false;
+                true ->
+                    case get_field(superseded_at, Key) of
+                        not_found -> true;
+                        {ok, SupAt} -> Now < SupAt
+                    end
+            end
+    end.
+
+verify_mac(Activity, Sig, Key) ->
+    case get_field(value, Sig) of
+        not_found -> {error, bad_signature};
+        {ok, SigValue} ->
+            case get_field(value, Key) of
+                not_found -> {error, bad_signature};
+                {ok, KeyMat} ->
+                    Bytes = canonical_bytes(Activity),
+                    Computed = crypto:hash(sha256,
+                        <<KeyMat/binary, Bytes/binary>>),
+                    case SigValue =:= Computed of
+                        true -> ok;
+                        false -> {error, bad_signature}
+                    end
+            end
+    end.

next/tests/envelope_sig.sh

@@ -0,0 +1,129 @@
+#!/usr/bin/env bash
+# next/tests/envelope_sig.sh — Step 2c acceptance test.
+#
+# Exercises envelope:verify_signature/2 against the full sig pipeline:
+# canonical_bytes + crypto:hash MAC + time-aware key validity per design
+# §9.6. 10 cases.
+#
+# The signature stand-in is HMAC-shaped:
+#   sig.value = crypto:hash(sha256, <<KeyMaterial/binary, CanonicalBytes/binary>>)
+# Real Ed25519/RSA verification is deferred to milestone 2 once the
+# corresponding crypto BIFs are wired.
+
+set -uo pipefail
+cd "$(git rev-parse --show-toplevel)"
+
+SX_SERVER="${SX_SERVER:-hosts/ocaml/_build/default/bin/sx_server.exe}"
+if [ ! -x "$SX_SERVER" ]; then
+  SX_SERVER="/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe"
+fi
+if [ ! -x "$SX_SERVER" ]; then
+  echo "ERROR: sx_server.exe not found." >&2
+  exit 1
+fi
+
+VERBOSE="${1:-}"
+PASS=0; FAIL=0; ERRORS=""
+TMPFILE=$(mktemp); trap "rm -f $TMPFILE" EXIT
+
+# Shared Erlang prelude builds a valid-signed envelope template and an
+# actor state with one active key. Each test reuses these and asserts
+# against an Erlang =:= comparison so the result is a bare boolean.
+PRELUDE='KM = <<1,2,3,4>>, U = [{actor,alice},{id,1},{published,100},{type,create}], CB = envelope:canonical_bytes(U), Sig = crypto:hash(sha256, <<KM/binary, CB/binary>>), Env = [{actor,alice},{id,1},{published,100},{type,create},{signature,[{algorithm,ed25519},{key_id,k1},{value,Sig}]}], AS = [{public_keys, [[{id,k1},{created,50},{value,KM}]]}],'
+
+cat > "$TMPFILE" <<EPOCHS
+(epoch 1)
+(load "lib/erlang/tokenizer.sx")
+(load "lib/erlang/parser.sx")
+(load "lib/erlang/parser-core.sx")
+(load "lib/erlang/parser-expr.sx")
+(load "lib/erlang/parser-module.sx")
+(load "lib/erlang/transpile.sx")
+(load "lib/erlang/runtime.sx")
+(load "lib/erlang/vm/dispatcher.sx")
+
+(epoch 2)
+(eval "(get (erlang-load-module (file-read \"next/kernel/envelope.erl\")) :name)")
+
+;; valid sig + active key -> ok
+(epoch 10)
+(eval "(get (erlang-eval-ast \"${PRELUDE} envelope:verify_signature(Env, AS) =:= ok\") :name)")
+
+;; tampered envelope (id mutated post-sign) -> bad_signature
+(epoch 11)
+(eval "(get (erlang-eval-ast \"${PRELUDE} Tampered = [{actor,alice},{id,999},{published,100},{type,create},{signature,[{algorithm,ed25519},{key_id,k1},{value,Sig}]}], envelope:verify_signature(Tampered, AS) =:= {error,bad_signature}\") :name)")
+
+;; wrong sig value (random bytes) -> bad_signature
+(epoch 12)
+(eval "(get (erlang-eval-ast \"${PRELUDE} BadEnv = [{actor,alice},{id,1},{published,100},{type,create},{signature,[{algorithm,ed25519},{key_id,k1},{value,<<0,0,0,0>>}]}], envelope:verify_signature(BadEnv, AS) =:= {error,bad_signature}\") :name)")
+
+;; unknown key_id -> no_active_key
+(epoch 13)
+(eval "(get (erlang-eval-ast \"${PRELUDE} OtherAS = [{public_keys, [[{id,k_other},{created,50},{value,KM}]]}], envelope:verify_signature(Env, OtherAS) =:= {error,no_active_key}\") :name)")
+
+;; key superseded BEFORE published -> no_active_key
+(epoch 14)
+(eval "(get (erlang-eval-ast \"${PRELUDE} SupAS = [{public_keys, [[{id,k1},{created,50},{superseded_at,80},{value,KM}]]}], envelope:verify_signature(Env, SupAS) =:= {error,no_active_key}\") :name)")
+
+;; key superseded AFTER published -> ok (historical valid)
+(epoch 15)
+(eval "(get (erlang-eval-ast \"${PRELUDE} SupAS2 = [{public_keys, [[{id,k1},{created,50},{superseded_at,200},{value,KM}]]}], envelope:verify_signature(Env, SupAS2) =:= ok\") :name)")
+
+;; key not yet created at published -> no_active_key
+(epoch 16)
+(eval "(get (erlang-eval-ast \"${PRELUDE} FutAS = [{public_keys, [[{id,k1},{created,150},{value,KM}]]}], envelope:verify_signature(Env, FutAS) =:= {error,no_active_key}\") :name)")
+
+;; missing signature field -> no_signature
+(epoch 17)
+(eval "(get (erlang-eval-ast \"${PRELUDE} envelope:verify_signature(U, AS) =:= {error,no_signature}\") :name)")
+
+;; actor state with no public_keys field -> no_keys
+(epoch 18)
+(eval "(get (erlang-eval-ast \"${PRELUDE} envelope:verify_signature(Env, []) =:= {error,no_keys}\") :name)")
+
+;; second key in list matches when first doesn't (lookup walks list)
+(epoch 19)
+(eval "(get (erlang-eval-ast \"${PRELUDE} TwoKeys = [{public_keys, [[{id,k_other},{created,50},{value,<<9,9,9>>}], [{id,k1},{created,50},{value,KM}]]}], envelope:verify_signature(Env, TwoKeys) =:= ok\") :name)")
+EPOCHS
+
+OUTPUT=$(timeout 120 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
+
+check() {
+  local epoch="$1" desc="$2" expected="$3"
+  local actual
+  actual=$(echo "$OUTPUT" | awk -v e="$epoch" '
+    $0 ~ "^\\(ok-len " e " " { getline; print; exit }
+    $0 ~ "^\\(ok " e " "     { print; exit }
+    $0 ~ "^\\(error " e " "  { print; exit }
+  ')
+  [ -z "$actual" ] && actual="<no output for epoch $epoch>"
+  if echo "$actual" | grep -qF -- "$expected"; then
+    PASS=$((PASS+1))
+    [ "$VERBOSE" = "-v" ] && echo "  ok $desc"
+  else
+    FAIL=$((FAIL+1))
+    ERRORS+="  FAIL [$desc] (epoch $epoch) expected: $expected | actual: $actual
+"
+  fi
+}
+
+check  2  "module load name"                "envelope"
+check 10  "valid sig active key"            "true"
+check 11  "tampered envelope"               "true"
+check 12  "wrong sig value"                 "true"
+check 13  "unknown key_id"                  "true"
+check 14  "key superseded before published" "true"
+check 15  "key superseded after published"  "true"
+check 16  "key not yet created"             "true"
+check 17  "missing signature field"         "true"
+check 18  "actor state no keys"             "true"
+check 19  "match second key in list"        "true"
+
+TOTAL=$((PASS+FAIL))
+if [ $FAIL -eq 0 ]; then
+  echo "ok $PASS/$TOTAL next/tests/envelope_sig.sh passed"
+else
+  echo "FAIL $PASS/$TOTAL passed, $FAIL failed:"
+  echo "$ERRORS"
+fi
+[ $FAIL -eq 0 ]

plans/fed-sx-milestone-1.md

@@ -153,7 +153,7 @@ canonicalize_sx(V) -> ...                  % sorts dict keys, normalizes strings
 **Sub-deliverables:**
 - [x] **2a** — `next/kernel/envelope.erl` `validate_shape/1` + `get_field/2` (property-list envelope; Erlang maps `#{}` not supported in this port) + `next/tests/envelope_shape.sh` (15 cases)
 - [x] **2b** — `canonical_bytes/1` over sig-stripped, key-sorted envelope (deterministic textual form via `cid:to_string` substrate; dag-cbor stand-in for v1) + `next/tests/envelope_canonical.sh` (8 cases)
-- [ ] **2c** — `verify_signature/2` against actor key set, time-aware key validity per design §9.6 + tests
+- [x] **2c** — `verify_signature/2` against actor `public_keys`, time-aware key validity per design §9.6 (created ≤ published, optional supersession check) + `next/tests/envelope_sig.sh` (11 cases). Signature scheme is HMAC-shaped (`crypto:hash(sha256, KeyMaterial ++ canonical_bytes)`) — RSA/Ed25519 verify deferred to m2 (BIFs not yet wired).
 
 **Deliverables:**
 
@@ -937,6 +937,7 @@ A few things still under-specified; resolve as work begins.
 Newest first. One line per sub-deliverable commit. Erlang conformance gate
 (`bash lib/erlang/conformance.sh`) must remain 729/729 on every entry.
 
+- **2026-05-26** — Step 2c: `envelope:verify_signature/2` — time-aware key lookup over `public_keys` (created ≤ published < superseded_at), MAC recompute via `crypto:hash(sha256, KeyMaterial ++ canonical_bytes)`, compared against `signature.value`. Returns ok or one of `no_signature | no_key_id | no_published | no_keys | no_active_key | bad_signature`. `next/tests/envelope_sig.sh` 11/11 pass. Erlang conformance 729/729.
 - **2026-05-26** — Step 2b: `envelope:canonical_bytes/1` — strip signature, insertion-sort property list by key, return host-CID-string as deterministic byte form (dag-cbor stand-in). `next/tests/envelope_canonical.sh` 8/8 pass. Erlang conformance 729/729 preserved.
 - **2026-05-26** — Step 2a: `next/kernel/envelope.erl` `validate_shape/1` + `get_field/2` over property-list envelopes (Erlang `#{}` maps not supported in this port). `next/tests/envelope_shape.sh` 15/15 pass. Erlang conformance 729/729 preserved.
 - **2026-05-26** — Step 1b: `next/kernel/nx_cid.erl` (from_sx/to_string/from_string/equals) — thin Erlang wrapper around the `cid:to_string/1` BIF. `next/tests/cid.sh` 13/13 pass. Module named `nx_cid` to avoid shadowing the `cid` BIF (user-module dispatch takes precedence over BIFs by module name). Erlang conformance 729/729 preserved.