func (c *crypter) Generate(key, salt []byte) (string, error) {
var rounds int
var isRoundsDef bool
if len(salt) == 0 {
salt = c.Salt.GenerateWRounds(SaltLenMax, RoundsDefault)
}
if !bytes.HasPrefix(salt, c.Salt.MagicPrefix) {
return "", common.ErrSaltPrefix
}
saltToks := bytes.Split(salt, []byte{'$'})
if len(saltToks) < 3 {
return "", common.ErrSaltFormat
}
if bytes.HasPrefix(saltToks[2], _rounds) {
isRoundsDef = true
pr, err := strconv.ParseInt(string(saltToks[2][7:]), 10, 32)
if err != nil {
return "", common.ErrSaltRounds
}
rounds = int(pr)
if rounds < RoundsMin {
rounds = RoundsMin
} else if rounds > RoundsMax {
rounds = RoundsMax
}
salt = saltToks[3]
} else {
rounds = RoundsDefault
salt = saltToks[2]
}
if len(salt) > 16 {
salt = salt[0:16]
}
// Compute alternate SHA512 sum with input KEY, SALT, and KEY.
Alternate := sha512.New()
Alternate.Write(key)
Alternate.Write(salt)
Alternate.Write(key)
AlternateSum := Alternate.Sum(nil) // 64 bytes
A := sha512.New()
A.Write(key)
A.Write(salt)
// Add for any character in the key one byte of the alternate sum.
i := len(key)
for ; i > 64; i -= 64 {
A.Write(AlternateSum)
}
A.Write(AlternateSum[0:i])
// Take the binary representation of the length of the key and for every add
// the alternate sum, for every 0 the key.
for i = len(key); i > 0; i >>= 1 {
if (i & 1) != 0 {
A.Write(AlternateSum)
} else {
A.Write(key)
}
}
Asum := A.Sum(nil)
// Start computation of P byte sequence.
P := sha512.New()
// For every character in the password add the entire password.
for i = 0; i < len(key); i++ {
P.Write(key)
}
Psum := P.Sum(nil)
// Create byte sequence P.
Pseq := make([]byte, 0, len(key))
for i = len(key); i > 64; i -= 64 {
Pseq = append(Pseq, Psum...)
}
Pseq = append(Pseq, Psum[0:i]...)
// Start computation of S byte sequence.
S := sha512.New()
for i = 0; i < (16 + int(Asum[0])); i++ {
S.Write(salt)
}
Ssum := S.Sum(nil)
// Create byte sequence S.
Sseq := make([]byte, 0, len(salt))
for i = len(salt); i > 64; i -= 64 {
Sseq = append(Sseq, Ssum...)
}
Sseq = append(Sseq, Ssum[0:i]...)
Csum := Asum
// Repeatedly run the collected hash value through SHA512 to burn CPU cycles.
for i = 0; i < rounds; i++ {
C := sha512.New()
// Add key or last result.
if (i & 1) != 0 {
C.Write(Pseq)
} else {
C.Write(Csum)
}
// Add salt for numbers not divisible by 3.
if (i % 3) != 0 {
C.Write(Sseq)
}
// Add key for numbers not divisible by 7.
if (i % 7) != 0 {
C.Write(Pseq)
}
// Add key or last result.
if (i & 1) != 0 {
C.Write(Csum)
} else {
C.Write(Pseq)
}
Csum = C.Sum(nil)
}
out := make([]byte, 0, 123)
out = append(out, c.Salt.MagicPrefix...)
if isRoundsDef {
out = append(out, []byte("rounds="+strconv.Itoa(rounds)+"$")...)
}
out = append(out, salt...)
out = append(out, '$')
out = append(out, common.Base64_24Bit([]byte{
Csum[42], Csum[21], Csum[0],
Csum[1], Csum[43], Csum[22],
Csum[23], Csum[2], Csum[44],
Csum[45], Csum[24], Csum[3],
Csum[4], Csum[46], Csum[25],
Csum[26], Csum[5], Csum[47],
Csum[48], Csum[27], Csum[6],
Csum[7], Csum[49], Csum[28],
Csum[29], Csum[8], Csum[50],
Csum[51], Csum[30], Csum[9],
Csum[10], Csum[52], Csum[31],
Csum[32], Csum[11], Csum[53],
Csum[54], Csum[33], Csum[12],
Csum[13], Csum[55], Csum[34],
Csum[35], Csum[14], Csum[56],
Csum[57], Csum[36], Csum[15],
Csum[16], Csum[58], Csum[37],
Csum[38], Csum[17], Csum[59],
Csum[60], Csum[39], Csum[18],
Csum[19], Csum[61], Csum[40],
Csum[41], Csum[20], Csum[62],
Csum[63],
})...)
// Clean sensitive data.
A.Reset()
Alternate.Reset()
P.Reset()
for i = 0; i < len(Asum); i++ {
Asum[i] = 0
}
for i = 0; i < len(AlternateSum); i++ {
AlternateSum[i] = 0
}
for i = 0; i < len(Pseq); i++ {
Pseq[i] = 0
}
return string(out), nil
}
func (c *crypter) Generate(key, salt []byte) (string, error) {
if len(salt) == 0 {
salt = c.Salt.Generate(SaltLenMax)
}
if !bytes.HasPrefix(salt, c.Salt.MagicPrefix) {
return "", common.ErrSaltPrefix
}
saltToks := bytes.Split(salt, []byte{'$'})
if len(saltToks) < 3 {
return "", common.ErrSaltFormat
} else {
salt = saltToks[2]
}
if len(salt) > 8 {
salt = salt[0:8]
}
// Compute alternate MD5 sum with input KEY, SALT, and KEY.
Alternate := md5.New()
Alternate.Write(key)
Alternate.Write(salt)
Alternate.Write(key)
AlternateSum := Alternate.Sum(nil) // 16 bytes
A := md5.New()
A.Write(key)
A.Write(c.Salt.MagicPrefix)
A.Write(salt)
// Add for any character in the key one byte of the alternate sum.
i := len(key)
for ; i > 16; i -= 16 {
A.Write(AlternateSum)
}
A.Write(AlternateSum[0:i])
// The original implementation now does something weird:
// For every 1 bit in the key, the first 0 is added to the buffer
// For every 0 bit, the first character of the key
// This does not seem to be what was intended but we have to follow this to
// be compatible.
for i = len(key); i > 0; i >>= 1 {
if (i & 1) == 0 {
A.Write(key[0:1])
} else {
A.Write([]byte{0})
}
}
Csum := A.Sum(nil)
// In fear of password crackers here comes a quite long loop which just
// processes the output of the previous round again.
// We cannot ignore this here.
for i = 0; i < RoundsDefault; i++ {
C := md5.New()
// Add key or last result.
if (i & 1) != 0 {
C.Write(key)
} else {
C.Write(Csum)
}
// Add salt for numbers not divisible by 3.
if (i % 3) != 0 {
C.Write(salt)
}
// Add key for numbers not divisible by 7.
if (i % 7) != 0 {
C.Write(key)
}
// Add key or last result.
if (i & 1) == 0 {
C.Write(key)
} else {
C.Write(Csum)
}
Csum = C.Sum(nil)
}
out := make([]byte, 0, 23+len(c.Salt.MagicPrefix)+len(salt))
out = append(out, c.Salt.MagicPrefix...)
out = append(out, salt...)
out = append(out, '$')
out = append(out, common.Base64_24Bit([]byte{
Csum[12], Csum[6], Csum[0],
Csum[13], Csum[7], Csum[1],
Csum[14], Csum[8], Csum[2],
Csum[15], Csum[9], Csum[3],
Csum[5], Csum[10], Csum[4],
Csum[11],
})...)
// Clean sensitive data.
A.Reset()
Alternate.Reset()
for i = 0; i < len(AlternateSum); i++ {
AlternateSum[i] = 0
}
return string(out), nil
}
