Verify roblobs (#13245)

* scaffolding for verification package

* WIP blob verification methods

* lock wrapper for safer forkchoice sharing

* more solid cache and verification designs; adding tests

* more test coverage, adding missing cache files

* clearer func name

* remove forkchoice borrower (it's in another PR)

* revert temporary interface experiment

* lint

* nishant feedback

* add comments with spec text to all verifications

* some comments on public methods

* invert confusing verification name

* deep source

* remove cache from ProposerCache + gaz

* more consistently early return on error paths

* messed up the test with the wrong config value

* terence naming feedback

* tests on BeginsAt

* lint

* deep source...

* name errors after failure, not expectation

* deep sooource

* check len()==0 instead of nil so empty lists work

* update test for EIP-7044

---------

Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>

time/slots/slottime.go

@@ -163,6 +163,12 @@ func ToTime(genesisTimeSec uint64, slot primitives.Slot) (time.Time, error) {
 	return time.Unix(int64(sTime), 0), nil // lint:ignore uintcast -- A timestamp will not exceed int64 in your lifetime.
 }
 
+// BeginsAt computes the timestamp where the given slot begins, relative to the genesis timestamp.
+func BeginsAt(slot primitives.Slot, genesis time.Time) time.Time {
+	sd := time.Second * time.Duration(params.BeaconConfig().SecondsPerSlot) * time.Duration(slot)
+	return genesis.Add(sd)
+}
+
 // Since computes the number of time slots that have occurred since the given timestamp.
 func Since(time time.Time) primitives.Slot {
 	return CurrentSlot(uint64(time.Unix()))

time/slots/slottime_test.go

@@ -153,6 +153,37 @@ func TestEpochStartSlot_OK(t *testing.T) {
 	}
 }
 
+func TestBeginsAtOK(t *testing.T) {
+	cases := []struct {
+		name     string
+		genesis  int64
+		slot     primitives.Slot
+		slotTime time.Time
+	}{
+		{
+			name:     "genesis",
+			slotTime: time.Unix(0, 0),
+		},
+		{
+			name:     "slot 1",
+			slot:     1,
+			slotTime: time.Unix(int64(params.BeaconConfig().SecondsPerSlot), 0),
+		},
+		{
+			name:     "slot 1",
+			slot:     32,
+			slotTime: time.Unix(int64(params.BeaconConfig().SecondsPerSlot)*32, 0),
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			genesis := time.Unix(c.genesis, 0)
+			st := BeginsAt(c.slot, genesis)
+			require.Equal(t, c.slotTime, st)
+		})
+	}
+}
+
 func TestEpochEndSlot_OK(t *testing.T) {
 	tests := []struct {
 		epoch     primitives.Epoch