Add Speck-128 implementation

cipher/cipher.go

@@ -0,0 +1,16 @@
+package cipher
+
+import "errors"
+
+var ErrInvalidKeyLength = errors.New("Invalid key length")
+
+type Block interface {
+	// Encrypt a source block into the destination. Panics if blocks are not sized correctly.
+	Encrypt(dst, src []byte)
+	// Decrypt a source block into the destination. Panics if blocks are not sized correctly.
+	Decrypt(dst, src []byte)
+	// BlockSize returns the blocksize in bytes
+	BlockSize() int
+	// Algorithm returns the name of the algorithm
+	Algorithm() string
+}