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utils.go
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/
utils.go
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package multi2
import (
"math/bits"
"encoding/binary"
)
// Endianness option
const littleEndian bool = false
func bytesToUint32s(b []byte) []uint32 {
size := len(b) / 4
dst := make([]uint32, size)
for i := 0; i < size; i++ {
j := i * 4
if littleEndian {
dst[i] = binary.LittleEndian.Uint32(b[j:])
} else {
dst[i] = binary.BigEndian.Uint32(b[j:])
}
}
return dst
}
func uint32sToBytes(w []uint32) []byte {
size := len(w) * 4
dst := make([]byte, size)
for i := 0; i < len(w); i++ {
j := i * 4
if littleEndian {
binary.LittleEndian.PutUint32(dst[j:], w[i])
} else {
binary.BigEndian.PutUint32(dst[j:], w[i])
}
}
return dst
}
func ROL(x uint32, n uint32) uint32 {
return bits.RotateLeft32(x, int(n))
}
func ROR(x uint32, n uint32) uint32 {
return ROL(x, 32 - n);
}
func pi1(p []uint32) {
p[1] ^= p[0]
}
func pi2(p []uint32, k []uint32) {
var t uint32
t = (p[1] + k[0]) & 0xFFFFFFFF
t = (ROL(t, 1) + t - 1) & 0xFFFFFFFF
t = (ROL(t, 4) ^ t) & 0xFFFFFFFF
p[0] ^= t
}
func pi3(p []uint32, k []uint32) {
var t uint32
t = p[0] + k[1]
t = (ROL(t, 2) + t + 1) & 0xFFFFFFFF
t = (ROL(t, 8) ^ t) & 0xFFFFFFFF
t = (t + k[2]) & 0xFFFFFFFF
t = (ROL(t, 1) - t) & 0xFFFFFFFF
t = ROL(t, 16) ^ (p[0] | t)
p[1] ^= t
}
func pi4(p []uint32, k []uint32) {
var t uint32
t = (p[1] + k[3]) & 0xFFFFFFFF
t = (ROL(t, 2) + t + 1) & 0xFFFFFFFF
p[0] ^= t
}
func setup(dk []uint32, k []uint32, uk []uint32) {
var n, t int32
var p [2]uint32
p[0] = dk[0]
p[1] = dk[1]
t = 4
n = 0
pi1(p[:])
pi2(p[:], k)
uk[n] = p[0]
n++
pi3(p[:], k)
uk[n] = p[1]
n++
pi4(p[:], k)
uk[n] = p[0]
n++
pi1(p[:])
uk[n] = p[1]
n++
pi2(p[:], k[t:])
uk[n] = p[0]
n++
pi3(p[:], k[t:])
uk[n] = p[1]
n++
pi4(p[:], k[t:])
uk[n] = p[0]
n++
pi1(p[:])
uk[n] = p[1]
n++
}
func encrypt(p []uint32, N int32, uk []uint32) {
var n, t int32
t, n = 0, 0
for {
pi1(p)
n++
if n == N {
break
}
pi2(p, uk[t:])
n++
if n == N {
break
}
pi3(p, uk[t:])
n++
if n == N {
break
}
pi4(p, uk[t:])
n++
if n == N {
break
}
t ^= 4
}
}
func decrypt(p []uint32, N int32, uk []uint32) {
var n, t int32
var nn int32
t = 4*(((N-1)>>2)&1)
n = N
for {
if n <= 4 {
nn = n
} else {
nn = ((n-1)%4)+1
}
switch nn {
case 4:
pi4(p, uk[t:])
n--
fallthrough
case 3:
pi3(p, uk[t:])
n--
fallthrough
case 2:
pi2(p, uk[t:])
n--
fallthrough
case 1:
pi1(p)
n--
case 0:
return
}
t ^= 4
}
}