58 lines
1.1 KiB
Go
58 lines
1.1 KiB
Go
package configfile
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import (
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"fmt"
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"math"
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"os"
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"golang.org/x/crypto/scrypt"
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"github.com/rfjakob/gocryptfs/internal/cryptocore"
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)
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const (
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// 1 << 16 uses 64MB of memory,
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// takes 4 seconds on my Atom Z3735F netbook
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ScryptDefaultLogN = 16
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)
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type scryptKdf struct {
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Salt []byte
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N int
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R int
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P int
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KeyLen int
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}
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func NewScryptKdf(logN int) scryptKdf {
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var s scryptKdf
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s.Salt = cryptocore.RandBytes(cryptocore.KeyLen)
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if logN <= 0 {
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s.N = 1 << ScryptDefaultLogN
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} else {
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if logN < 10 {
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fmt.Println("Error: scryptn below 10 is too low to make sense. Aborting.")
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os.Exit(1)
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}
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s.N = 1 << uint32(logN)
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}
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s.R = 8 // Always 8
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s.P = 1 // Always 1
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s.KeyLen = cryptocore.KeyLen
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return s
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}
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func (s *scryptKdf) DeriveKey(pw string) []byte {
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k, err := scrypt.Key([]byte(pw), s.Salt, s.N, s.R, s.P, s.KeyLen)
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if err != nil {
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panic(fmt.Sprintf("DeriveKey failed: %s", err.Error()))
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}
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return k
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}
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// LogN - N is saved as 2^LogN, but LogN is much easier to work with.
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// This function gives you LogN = Log2(N).
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func (s *scryptKdf) LogN() int {
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return int(math.Log2(float64(s.N)) + 0.5)
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}
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