slip39 0.1.5-dev.1

The dart implementation of the SLIP39 for Shamir's Secret-Sharing for Mnemonic Codes.

slip39-dart

The dart implementation of the SLIP39 for Shamir's Secret-Sharing for Mnemonic Codes.

The code based on the Reference implementation of SLIP-0039.

DISCLAIMER

This project is still in early development phase. Use it at your own risk.

Description

This SLIP39 implementation uses a 3 level height (l=3) of a 16 degree (d=16) tree (T), which is represented as an array of the level two nodes (groups, G).

The degree (d) and the level (l) of the tree are 16 and 3 respectively, which means that max d^(l-1), i.e. 16^2, leaf nodes (M) can be in a complete tree (or forest).

The first level (l=1) node of the tree is the the root (R), the level 2 ones are the SSS groups (Gs or group nodes) e.g. [G0, ..., Gd].

The last, the third, level nodes are the only leafs (M, group members) which contains the generated mnemonics.

Every node has two values:

• the N and
• M i.e. n(N,M).

Whihc means, that N (threshold) number of M children are required to reconstruct the node's secret.

Format

The tree's human friendly array representation only uses the group (l=2) nodes as arrays. For example. : [[1,1], [1,1], [3,5], [2,6]] The group's first parameter is the N (group threshold) while the second is the M, the number of members in the group. See, details in Example.

Installing

Add the following into the pubspec.yaml:

dependencies:
  slip39: ^0.1.3

Example

import 'package:slip39/slip39dart';

int main() {
// threshold (N) number of group shares required to reconstruct the master secret.
final threshold = 2;
final masterSecret = "ABCDEFGHIJKLMNOP";
final passphrase = "TREZOR";

// 4 groups shares and 2 are required to reconstruct the master secret.
final groups = [
  // Alice group shares. 1 is enough to reconstruct a group share,
  // therefore she needs at least two group shares to be reconstructed,
  [1, 1],
  [1, 1],
  // 3 of 5 Friends' shares are required to reconstruct this group share
  [3, 5],
  // 2 of 6 Family's shares are required to reconstruct this group share
  [2, 6]
];

final slip = Slip39.fromArray(
    masterSecret: masterSecret,
    passphrase: passphrase,
    threshold: threshold,
    groups: groups);

// One of Alice's share
final aliceShare = slip.fromPath('r/0').mnemonics;

// and any two of family's shares.
var familyShares = slip.fromPath('r/3/1').mnemonics;
familyShares = familyShares..addAll(slip.fromPath('r/3/3').mnemonics);

final allShares = aliceShare..addAll(familyShares);

print("Shares used for restoring the master secret:");
allShares..forEach((s) => print(s));

final recoveredSecret = Slip39.recoverSecret(allShares, passphrase);
assert(masterSecret == recoveredSecret);
print("Recovered secret: $recoveredSecret");
}

TODOS

• Add unit tests.
• Test with the reference code's test vectors.
• Refactor the helpers to different helper classes e.g. CryptoHelper(), ShamirHelper() etc.
• Add JSON representation, see JSON representation below.
• Refactor to much simpler code.

JSON Representation

  {
  "name": "Slip39",
  "threshold": 2,
  "shares": [
    {
      "name": "My Primary",
      "threshold": 1,
      "shares": [
        "Primary"
      ]
    },
    {
      "name": "My Secondary",
      "threshold": 1,
      "shares": [
        "Secondary"
      ]
    },
    {
      "name": "Friends",
      "threshold": 3,
      "shares": [
        "Alice",
        "Bob",
        "Charlie",
        "David",
        "Erin"
      ]
    },
    {
      "name": "Family",
      "threshold": 2,
      "shares": [
        "Adam",
        "Brenda",
        "Carol",
        "Dan",
        "Edward",
        "Frank"
      ]
    }
  ]
}

LICENSE

CopyRight (c) 2019 Pal Dorogi "iLap" [e-mail]

MIT License