marshaller

Serializes go-passwd/hasher hashers to / from a single string in a Django-style format.

Installation

go get github.com/go-passwd/marshaller

Usage

import (
    "github.com/go-passwd/hasher"
    "github.com/go-passwd/marshaller"
)

h, _ := hasher.New(hasher.TypeSHA256)
h.SetPassword("secret")

s, _ := marshaller.DjangoMarshaller.Marshal(h)
// s == "sha256$2048$<salt>$<hex-digest>"

restored, _ := marshaller.DjangoMarshaller.Unmarshal(s)
restored.Check("secret") // true

Format

Output adapts to whether iter and salt carry information:

Iter	Salt	Format
> 1	non-empty	code$iter$salt$digest
> 1	empty	code$iter$digest
<= 1	non-empty	code$salt$digest
<= 1	empty	code$digest

The default separator is $. The default DjangoMarshaller encodes the digest as hex; Base64Marshaller encodes it as standard base64 (matching how Django's PBKDF2 stores hashes).

Predefined marshallers

• DjangoMarshaller — HexMarshaller{Separator: "$"}
• HexMarshaller{Separator: ":"} — same format with a different separator
• Base64Marshaller{Separator: "$"} — base64 instead of hex

Caveats

• The 3-segment form distinguishes iter from salt by trying to parse the middle segment as an integer. A purely numeric salt would be misread as iter. randomstring.Generate produces alphanumeric salts, so this only matters for hand-crafted salts.
• The format is Django-style, not Django-compatible: real Django MD5PasswordHasher and SHA1PasswordHasher use a 3-field algo$salt$hex shape with a single un-iterated digest.

Implementing your own hasher

To make a custom hasher.Hasher marshallable, implement marshaller.Marshalable:

type Marshalable interface {
    Code() string
    HashIter() int
    HashSalt() string
    HashedPassword() []byte
}

All hashers in go-passwd/hasher already do this.