git add files

1 files changed, 35 insertions, 0 deletions

diff --git a/helper.go b/helper.go
new file mode 100644
index 0000000..8fc8ccb
--- /dev/null
+++ b/helper.go
@@ -0,0 +1,35 @@
+package rabaead
+
+import (
+	"encoding/binary"
+
+	"snix.ir/poly1305"
+)
+
+func headtail(in []byte, n int) (head, tail []byte) {
+	total := len(in) + n
+
+	if cap(in) >= total {
+		head = in[:total]
+	} else {
+		head = make([]byte, total)
+		copy(head, in)
+	}
+	tail = head[len(in):]
+	return
+}
+
+func writePadding(p *poly1305.MAC, b []byte) {
+	p.Write(b)
+	if rem := len(b) % 16; rem != 0 {
+		var buf [16]byte
+		padLen := 16 - rem
+		p.Write(buf[:padLen])
+	}
+}
+
+func writeUint64(p *poly1305.MAC, n int) {
+	var buf [8]byte
+	binary.LittleEndian.PutUint64(buf[:], uint64(n))
+	p.Write(buf[:])
+}