init

net/CFB8/cfb8.go

@@ -0,0 +1,54 @@
+//From https://play.golang.org/p/LTbId4b6M2
+
+package CFB8
+
+import "crypto/cipher"
+
+type CFB8 struct {
+	c         cipher.Block
+	blockSize int
+	iv, tmp   []byte
+	de        bool
+}
+
+func NewCFB8Decrypt(c cipher.Block, iv []byte) *CFB8 {
+	cp := make([]byte, len(iv))
+	copy(cp, iv)
+	return &CFB8{
+		c:         c,
+		blockSize: c.BlockSize(),
+		iv:        cp,
+		tmp:       make([]byte, c.BlockSize()),
+		de:        true,
+	}
+}
+
+func NewCFB8Encrypt(c cipher.Block, iv []byte) *CFB8 {
+	cp := make([]byte, len(iv))
+	copy(cp, iv)
+	return &CFB8{
+		c:         c,
+		blockSize: c.BlockSize(),
+		iv:        cp,
+		tmp:       make([]byte, c.BlockSize()),
+		de:        false,
+	}
+}
+
+func (cf *CFB8) XORKeyStream(dst, src []byte) {
+	for i := 0; i < len(src); i++ {
+		val := src[i]
+		copy(cf.tmp, cf.iv)
+		cf.c.Encrypt(cf.iv, cf.iv)
+		val = val ^ cf.iv[0]
+
+		copy(cf.iv, cf.tmp[1:])
+		if cf.de {
+			cf.iv[15] = src[i]
+		} else {
+			cf.iv[15] = val
+		}
+
+		dst[i] = val
+	}
+}