if isEncrypted {
			dec, err := decrypt(oi.Parts[firstPartIdx].Index)
			if err == nil {
				// Load Index
				var idx s2.Index
				_, err := idx.Load(s2.RestoreIndexHeaders(dec))

				// Find compressed/uncompressed offsets of our partskip
				compOff, uCompOff, err2 := idx.Find(partSkip)

				if err == nil && err2 == nil && compOff > 0 {
					// Encrypted.

				t.Errorf("index returned above threshold")
			}
			if tt.wantIdx {
				if idx == nil {
					t.Errorf("no index returned")
				}
				var index s2.Index
				_, err = index.Load(s2.RestoreIndexHeaders(idx))
				if err != nil {
					t.Errorf("error loading index: %v", err)
				}
				t.Log("size:", len(idx))
				t.Log(string(index.JSON()))
				if index.TotalUncompressed != int64(len(tt.data)) {