350 lines
7.9 KiB
Go
350 lines
7.9 KiB
Go
package utils
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import (
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"bytes"
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"crypto/rand"
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"crypto/sha512"
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"errors"
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"strconv"
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)
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// code in this file taken from https://github.com/tredoe/osutil/blob/master/v2/userutil/crypt/sha512_crypt/sha512_crypt.go
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var (
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ErrSaltPrefix = errors.New("invalid magic prefix")
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ErrSaltFormat = errors.New("invalid salt format")
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ErrSaltRounds = errors.New("invalid rounds")
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)
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// Salt represents a salt.
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type Salt struct {
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MagicPrefix []byte
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SaltLenMin int
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SaltLenMax int
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RoundsMin int
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RoundsMax int
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RoundsDefault int
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}
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type crypter struct{ Salt Salt }
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var _rounds = []byte("rounds=")
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const (
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MagicPrefix = "$6$"
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SaltLenMin = 1
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SaltLenMax = 16
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RoundsMin = 1000
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RoundsMax = 999999999
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RoundsDefault = 5000
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alphabet = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
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)
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// Generate generates a random salt of a given length.
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//
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// The length is set thus:
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//
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// length > SaltLenMax: length = SaltLenMax
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// length < SaltLenMin: length = SaltLenMin
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func (s *Salt) Generate(length int) []byte {
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if length > s.SaltLenMax {
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length = s.SaltLenMax
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} else if length < s.SaltLenMin {
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length = s.SaltLenMin
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}
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saltLen := (length * 6 / 8)
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if (length*6)%8 != 0 {
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saltLen++
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}
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salt := make([]byte, saltLen)
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rand.Read(salt)
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out := make([]byte, len(s.MagicPrefix)+length)
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copy(out, s.MagicPrefix)
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copy(out[len(s.MagicPrefix):], Base64_24Bit(salt))
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return out
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}
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// GenerateWRounds creates a random salt with the random bytes being of the
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// length provided, and the rounds parameter set as specified.
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//
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// The parameters are set thus:
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//
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// length > SaltLenMax: length = SaltLenMax
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// length < SaltLenMin: length = SaltLenMin
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//
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// rounds < 0: rounds = RoundsDefault
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// rounds < RoundsMin: rounds = RoundsMin
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// rounds > RoundsMax: rounds = RoundsMax
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//
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// If rounds is equal to RoundsDefault, then the "rounds=" part of the salt is
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// removed.
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func (s *Salt) GenerateWRounds(length, rounds int) []byte {
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if length > s.SaltLenMax {
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length = s.SaltLenMax
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} else if length < s.SaltLenMin {
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length = s.SaltLenMin
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}
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if rounds < 0 {
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rounds = s.RoundsDefault
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} else if rounds < s.RoundsMin {
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rounds = s.RoundsMin
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} else if rounds > s.RoundsMax {
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rounds = s.RoundsMax
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}
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//fmt.Printf("GenerateWRounds length is %d and rounds is %d\n", length, rounds)
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saltLen := (length * 6 / 8)
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if (length*6)%8 != 0 {
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saltLen++
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}
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salt := make([]byte, saltLen)
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rand.Read(salt)
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roundsText := ""
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if rounds != s.RoundsDefault {
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roundsText = "rounds=" + strconv.Itoa(rounds) + "$"
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}
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out := make([]byte, len(s.MagicPrefix)+len(roundsText)+length)
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copy(out, s.MagicPrefix)
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//fmt.Printf("GenerateWRounds copy 1 : '%v'\n", out)
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copy(out[len(s.MagicPrefix):], []byte(roundsText))
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//fmt.Printf("GenerateWRounds copy 2 : '%v'\n", out)
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copy(out[len(s.MagicPrefix)+len(roundsText):], Base64_24Bit(salt))
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//fmt.Printf("GenerateWRounds copy 3 : '%v'\n", out)
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return out
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}
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func Base64_24Bit(src []byte) (hash []byte) {
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if len(src) == 0 {
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return []byte{} // TODO: return nil
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}
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hashSize := (len(src) * 8) / 6
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if (len(src) % 6) != 0 {
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hashSize += 1
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}
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hash = make([]byte, hashSize)
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dst := hash
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for len(src) > 0 {
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switch len(src) {
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default:
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dst[0] = alphabet[src[0]&0x3f]
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dst[1] = alphabet[((src[0]>>6)|(src[1]<<2))&0x3f]
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dst[2] = alphabet[((src[1]>>4)|(src[2]<<4))&0x3f]
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dst[3] = alphabet[(src[2]>>2)&0x3f]
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src = src[3:]
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dst = dst[4:]
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case 2:
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dst[0] = alphabet[src[0]&0x3f]
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dst[1] = alphabet[((src[0]>>6)|(src[1]<<2))&0x3f]
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dst[2] = alphabet[(src[1]>>4)&0x3f]
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src = src[2:]
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dst = dst[3:]
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case 1:
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dst[0] = alphabet[src[0]&0x3f]
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dst[1] = alphabet[(src[0]>>6)&0x3f]
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src = src[1:]
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dst = dst[2:]
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}
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}
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return
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}
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func Generate(key, salt []byte) (string, error) {
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var rounds int
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var isRoundsDef bool
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var c crypter
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c.Salt = GetSalt()
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if len(salt) == 0 {
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salt = c.Salt.GenerateWRounds(SaltLenMax, RoundsDefault)
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//fmt.Printf("Generate created salt with value '%v'\n", salt)
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}
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if !bytes.HasPrefix(salt, c.Salt.MagicPrefix) {
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//fmt.Printf("Generate salt '%v' has no magic prefix\n", salt)
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return "", ErrSaltPrefix
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}
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saltToks := bytes.Split(salt, []byte{'$'})
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if len(saltToks) < 3 {
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return "", ErrSaltFormat
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}
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if bytes.HasPrefix(saltToks[2], _rounds) {
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isRoundsDef = true
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pr, err := strconv.ParseInt(string(saltToks[2][7:]), 10, 32)
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if err != nil {
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return "", ErrSaltRounds
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}
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rounds = int(pr)
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if rounds < RoundsMin {
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rounds = RoundsMin
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} else if rounds > RoundsMax {
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rounds = RoundsMax
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}
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salt = saltToks[3]
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} else {
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rounds = RoundsDefault
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salt = saltToks[2]
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}
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if len(salt) > SaltLenMax {
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salt = salt[0:SaltLenMax]
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}
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// Compute alternate SHA512 sum with input KEY, SALT, and KEY.
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Alternate := sha512.New()
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Alternate.Write(key)
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Alternate.Write(salt)
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Alternate.Write(key)
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AlternateSum := Alternate.Sum(nil) // 64 bytes
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A := sha512.New()
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A.Write(key)
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A.Write(salt)
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// Add for any character in the key one byte of the alternate sum.
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i := len(key)
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for ; i > 64; i -= 64 {
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A.Write(AlternateSum)
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}
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A.Write(AlternateSum[0:i])
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// Take the binary representation of the length of the key and for every add
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// the alternate sum, for every 0 the key.
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for i = len(key); i > 0; i >>= 1 {
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if (i & 1) != 0 {
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A.Write(AlternateSum)
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} else {
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A.Write(key)
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}
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}
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Asum := A.Sum(nil)
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// Start computation of P byte sequence.
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P := sha512.New()
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// For every character in the password add the entire password.
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for i = 0; i < len(key); i++ {
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P.Write(key)
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}
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Psum := P.Sum(nil)
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// Create byte sequence P.
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Pseq := make([]byte, 0, len(key))
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for i = len(key); i > 64; i -= 64 {
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Pseq = append(Pseq, Psum...)
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}
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Pseq = append(Pseq, Psum[0:i]...)
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// Start computation of S byte sequence.
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S := sha512.New()
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for i = 0; i < (16 + int(Asum[0])); i++ {
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S.Write(salt)
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}
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Ssum := S.Sum(nil)
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// Create byte sequence S.
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Sseq := make([]byte, 0, len(salt))
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for i = len(salt); i > 64; i -= 64 {
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Sseq = append(Sseq, Ssum...)
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}
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Sseq = append(Sseq, Ssum[0:i]...)
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Csum := Asum
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// Repeatedly run the collected hash value through SHA512 to burn CPU cycles.
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for i = 0; i < rounds; i++ {
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C := sha512.New()
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// Add key or last result.
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if (i & 1) != 0 {
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C.Write(Pseq)
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} else {
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C.Write(Csum)
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}
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// Add salt for numbers not divisible by 3.
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if (i % 3) != 0 {
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C.Write(Sseq)
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}
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// Add key for numbers not divisible by 7.
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if (i % 7) != 0 {
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C.Write(Pseq)
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}
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// Add key or last result.
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if (i & 1) != 0 {
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C.Write(Csum)
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} else {
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C.Write(Pseq)
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}
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Csum = C.Sum(nil)
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}
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out := make([]byte, 0, 123)
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out = append(out, MagicPrefix...)
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if isRoundsDef {
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out = append(out, []byte("rounds="+strconv.Itoa(rounds)+"$")...)
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}
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out = append(out, salt...)
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out = append(out, '$')
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out = append(out, Base64_24Bit([]byte{
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Csum[42], Csum[21], Csum[0],
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Csum[1], Csum[43], Csum[22],
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Csum[23], Csum[2], Csum[44],
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Csum[45], Csum[24], Csum[3],
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Csum[4], Csum[46], Csum[25],
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Csum[26], Csum[5], Csum[47],
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Csum[48], Csum[27], Csum[6],
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Csum[7], Csum[49], Csum[28],
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Csum[29], Csum[8], Csum[50],
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Csum[51], Csum[30], Csum[9],
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Csum[10], Csum[52], Csum[31],
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Csum[32], Csum[11], Csum[53],
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Csum[54], Csum[33], Csum[12],
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Csum[13], Csum[55], Csum[34],
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Csum[35], Csum[14], Csum[56],
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Csum[57], Csum[36], Csum[15],
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Csum[16], Csum[58], Csum[37],
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Csum[38], Csum[17], Csum[59],
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Csum[60], Csum[39], Csum[18],
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Csum[19], Csum[61], Csum[40],
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Csum[41], Csum[20], Csum[62],
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Csum[63],
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})...)
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// Clean sensitive data.
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A.Reset()
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Alternate.Reset()
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P.Reset()
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for i = 0; i < len(Asum); i++ {
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Asum[i] = 0
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}
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for i = 0; i < len(AlternateSum); i++ {
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AlternateSum[i] = 0
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}
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for i = 0; i < len(Pseq); i++ {
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Pseq[i] = 0
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}
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return string(out), nil
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}
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func (c *crypter) SetSalt(salt Salt) { c.Salt = salt }
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func GetSalt() Salt {
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return Salt{
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MagicPrefix: []byte(MagicPrefix),
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SaltLenMin: SaltLenMin,
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SaltLenMax: SaltLenMax,
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RoundsDefault: RoundsDefault,
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RoundsMin: RoundsMin,
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RoundsMax: RoundsMax,
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}
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}
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