1 files changed, 35 insertions, 0 deletions
diff --git a/internal/stupidgcm/chacha.go b/internal/stupidgcm/chacha.go
new file mode 100644
index 0000000..37f7e1f
--- /dev/null
+++ b/internal/stupidgcm/chacha.go
@@ -0,0 +1,35 @@
+// +build !without_openssl
+
+package stupidgcm
+
+import (
+	"crypto/cipher"
+	"log"
+
+	"golang.org/x/crypto/chacha20poly1305"
+)
+
+/*
+#include <openssl/evp.h>
+*/
+import "C"
+
+type stupidChacha20poly1305 struct {
+	stupidAEADCommon
+}
+
+// Verify that we satisfy the cipher.AEAD interface
+var _ cipher.AEAD = &stupidChacha20poly1305{}
+
+func newChacha20poly1305(key []byte) *stupidChacha20poly1305 {
+	if len(key) != chacha20poly1305.KeySize {
+		log.Panicf("Only %d-byte keys are supported, you passed %d bytes", chacha20poly1305.KeySize, len(key))
+	}
+	return &stupidChacha20poly1305{
+		stupidAEADCommon{
+			key:              append([]byte{}, key...), // private copy
+			openSSLEVPCipher: C.EVP_chacha20_poly1305(),
+			nonceSize:        chacha20poly1305.NonceSize,
+		},
+	}
+}