go/src/crypto/des/block.go

func cryptBlock(subkeys []uint64, dst, src []byte, decrypt bool) { … }

// DES Feistel function. feistelBox must be initialized via
// feistelBoxOnce.Do(initFeistelBox) first.
func feistel(l, r uint32, k0, k1 uint64) (lout, rout uint32) { … }

var feistelBox …

var feistelBoxOnce …

// general purpose function to perform DES block permutations.
func permuteBlock(src uint64, permutation []uint8) (block uint64) { … }

func initFeistelBox() { … }

// permuteInitialBlock is equivalent to the permutation defined
// by initialPermutation.
func permuteInitialBlock(block uint64) uint64 { … }

// permuteFinalBlock is equivalent to the permutation defined
// by finalPermutation.
func permuteFinalBlock(block uint64) uint64 { … }

// creates 16 28-bit blocks rotated according
// to the rotation schedule.
func ksRotate(in uint32) (out []uint32) { … }

// creates 16 56-bit subkeys from the original key.
func (c *desCipher) generateSubkeys(keyBytes []byte) { … }

// Expand 48-bit input to 64-bit, with each 6-bit block padded by extra two bits at the top.
// By doing so, we can have the input blocks (four bits each), and the key blocks (six bits each) well-aligned without
// extra shifts/rotations for alignments.
func unpack(x uint64) uint64 { … }