f = (f << 1) | (f >> 31)

				feistelBox[s][t] = uint32(f)
			}
		}
	}
}

// permuteInitialBlock is equivalent to the permutation defined
// by initialPermutation.
func permuteInitialBlock(block uint64) uint64 {
	// block = b7 b6 b5 b4 b3 b2 b1 b0 (8 bytes)
	b1 := block >> 48
	b2 := block << 48
	block ^= b1 ^ b2 ^ b1<<48 ^ b2>>48

		panic("crypto/des: output not full block")
	}
	if alias.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
		panic("crypto/des: invalid buffer overlap")
	}

	b := byteorder.BeUint64(src)
	b = permuteInitialBlock(b)
	left, right := uint32(b>>32), uint32(b)

	left = (left << 1) | (left >> 31)
	right = (right << 1) | (right >> 31)

	for i := 0; i < 8; i++ {