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Task/The-ISAAC-Cipher/Go/the-isaac-cipher.go

@@ -0,0 +1,119 @@
+package main
+
+import "fmt"
+
+const (
+    msg = "a Top Secret secret"
+    key = "this is my secret key"
+)
+
+func main() {
+    var z state
+    z.seed(key)
+    fmt.Println("Message: ", msg)
+    fmt.Println("Key    : ", key)
+    fmt.Println("XOR    : ", z.vernam(msg))
+}
+
+type state struct {
+    aa, bb, cc uint32
+    mm         [256]uint32
+    randrsl    [256]uint32
+    randcnt    int
+}
+
+func (z *state) isaac() {
+    z.cc++
+    z.bb += z.cc
+    for i, x := range z.mm {
+        switch i % 4 {
+        case 0:
+            z.aa = z.aa ^ z.aa<<13
+        case 1:
+            z.aa = z.aa ^ z.aa>>6
+        case 2:
+            z.aa = z.aa ^ z.aa<<2
+        case 3:
+            z.aa = z.aa ^ z.aa>>16
+        }
+        z.aa += z.mm[(i+128)%256]
+        y := z.mm[x>>2%256] + z.aa + z.bb
+        z.mm[i] = y
+        z.bb = z.mm[y>>10%256] + x
+        z.randrsl[i] = z.bb
+    }
+}
+
+func (z *state) randInit() {
+    const gold = uint32(0x9e3779b9)
+    a := [8]uint32{gold, gold, gold, gold, gold, gold, gold, gold}
+    mix1 := func(i int, v uint32) {
+        a[i] ^= v
+        a[(i+3)%8] += a[i]
+        a[(i+1)%8] += a[(i+2)%8]
+    }
+    mix := func() {
+        mix1(0, a[1]<<11)
+        mix1(1, a[2]>>2)
+        mix1(2, a[3]<<8)
+        mix1(3, a[4]>>16)
+        mix1(4, a[5]<<10)
+        mix1(5, a[6]>>4)
+        mix1(6, a[7]<<8)
+        mix1(7, a[0]>>9)
+    }
+    for i := 0; i < 4; i++ {
+        mix()
+    }
+    for i := 0; i < 256; i += 8 {
+        for j, rj := range z.randrsl[i : i+8] {
+            a[j] += rj
+        }
+        mix()
+        for j, aj := range a {
+            z.mm[i+j] = aj
+        }
+    }
+    for i := 0; i < 256; i += 8 {
+        for j, mj := range z.mm[i : i+8] {
+            a[j] += mj
+        }
+        mix()
+        for j, aj := range a {
+            z.mm[i+j] = aj
+        }
+    }
+    z.isaac()
+}
+
+func (z *state) seed(seed string) {
+    for i, r := range seed {
+        if i == 256 {
+            break
+        }
+        z.randrsl[i] = uint32(r)
+    }
+    z.randInit()
+}
+
+func (z *state) random() (r uint32) {
+    r = z.randrsl[z.randcnt]
+    z.randcnt++
+    if z.randcnt == 256 {
+        z.isaac()
+        z.randcnt = 0
+    }
+    return
+}
+
+func (z *state) randA() byte {
+    return byte(z.random()%95 + 32)
+}
+
+func (z *state) vernam(msg string) string {
+    b := []byte(msg)
+    for i := range b {
+        b[i] ^= z.randA()
+    }
+    return fmt.Sprintf("%X", b)
+}