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package kdf
import (
"fmt"
"math"
"github.com/pkg/errors"
)
const (
bcryptHash = "2a"
scryptHash = "scrypt"
scryptHash16384 = "scrypt-16384"
scryptHash32768 = "scrypt-32768"
scryptHash65536 = "scrypt-65536"
)
var (
// ScryptMaxCost the the maximum value for ln. Maximum is set to avoid
// panics due to not enough memory errors. Memory used is ~4*32*(2^ln)*r
// bytes.
ScryptMaxCost = 20
// ScryptMaxBlockSize is the maximum value for r. The maximum is set to
// avoid panics due to not enough memory errors. Memory used is
// ~4*32*(2^ln)*r bytes.
ScryptMaxBlockSize = 32
// ScryptMaxParallelism is the maximum value for p.
ScryptMaxParallelism = 32
)
var scryptParams = map[string]scryptParam{
scryptHash16384: {16384, 8, 1, 32},
scryptHash32768: {32768, 8, 1, 32},
scryptHash65536: {65536, 8, 1, 32},
}
type scryptParam struct {
N, r, p int
kl int
}
func newScryptParams(s string) (*scryptParam, error) {
params := phcParamsToMap(s)
ln, err := phcAtoi(params["ln"], 16)
if err != nil || ln < 1 || ln > ScryptMaxCost {
return nil, errors.Errorf("invalid scrypt parameter ln=%s", params["ln"])
}
r, err := phcAtoi(params["r"], 8)
if err != nil || r < 1 || r > ScryptMaxBlockSize {
return nil, errors.Errorf("invalid scrypt parameter r=%s", params["r"])
}
p, err := phcAtoi(params["p"], 1)
if err != nil || p < 1 || p > ScryptMaxParallelism {
return nil, errors.Errorf("invalid scrypt parameter p=%s", params["p"])
}
return &scryptParam{
N: int(math.Pow(2, float64(ln))),
r: r,
p: p,
}, nil
}
func (s *scryptParam) getParams() string {
return fmt.Sprintf("ln=%d,r=%d,p=%d", int(math.Log2(float64(s.N))), s.r, s.p)
}
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