stupidgcm: introduce stupidAEADCommon and use for both chacha & gcm

Nice deduplication and brings the GCM decrypt speed up to par.

internal/speed$ benchstat old new
name                old time/op   new time/op   delta
StupidGCM-4          4.71µs ± 0%   4.66µs ± 0%   -0.99%  (p=0.008 n=5+5)
StupidGCMDecrypt-4   5.77µs ± 1%   4.51µs ± 0%  -21.80%  (p=0.008 n=5+5)

name                old speed     new speed     delta
StupidGCM-4         870MB/s ± 0%  879MB/s ± 0%   +1.01%  (p=0.008 n=5+5)
StupidGCMDecrypt-4  710MB/s ± 1%  908MB/s ± 0%  +27.87%  (p=0.008 n=5+5)

1 files changed, 0 insertions, 28 deletions

diff --git a/internal/stupidgcm/stupidgcm_test.go b/internal/stupidgcm/stupidgcm_test.go
deleted file mode 100644
index 5323afa..0000000
--- a/internal/stupidgcm/stupidgcm_test.go
+++ /dev/null
@@ -1,28 +0,0 @@
-// +build !without_openssl
-
-// We compare against Go's built-in GCM implementation. Since stupidgcm only
-// supports 128-bit IVs and Go only supports that from 1.5 onward, we cannot
-// run these tests on older Go versions.
-package stupidgcm
-
-import (
-	"crypto/aes"
-	"crypto/cipher"
-	"testing"
-)
-
-func TestStupidGCM(t *testing.T) {
-	key := randBytes(32)
-	sGCM := New(key, false)
-
-	gAES, err := aes.NewCipher(key)
-	if err != nil {
-		t.Fatal(err)
-	}
-	gGCM, err := cipher.NewGCMWithNonceSize(gAES, 16)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	testCiphers(t, sGCM, gGCM)
-}