diff --git a/crypto/AEAD.go b/crypto/AEAD.go
new file mode 100644
index 00000000..d6804179
--- /dev/null
+++ b/crypto/AEAD.go
@@ -0,0 +1,8 @@
+package crypto
+
+import "io"
+
+// An AEAD implements QUIC's authenticated encryption and associated data
+type AEAD interface {
+	Open(associatedData []byte, ciphertext io.Reader) (io.Reader, error)
+}