/*
 * Copyright (c) 2013-2016 Galois, Inc.
 * Distributed under the terms of the BSD3 license (see LICENSE file)
 */
module Keys where

import CfrgCurves
import Blake2s
import SCrypt
import Base58

type MinilockID = [46][8]

// Given a public key compute the ASCII ID
encodeID : Public25519 -> MinilockID
encodeID pub = base58enc (join (pub # [h]))
  where
  h = blake2s `{nn=1} pub : [8]

decodeID : MinilockID -> (Bit,Public25519)
decodeID ident = (hComp == hRecv, key)
 where
  bs    = split (base58dec ident)  : [33][8]
  hRecv = bs ! 0
  hComp = blake2s `{nn=1} key      : [8]
  key   = take bs                  : [32][8]

// Accept a possibly-short key (base58 is value dependent encoding)
// and expand it to the full, fixed, size.
mkFullLengthID : {n} (46 >= n, n>= 1) => [n][8] -> MinilockID
mkFullLengthID n = drop (['1' | _ <- [0..45] : [_][8]]  # n)

mkID : {passBytes, saltBytes}
       ( fin passBytes, fin saltBytes
       , 64 >= width passBytes
       , 32 >= width (4*saltBytes)
       )
    => [passBytes][8] -> [saltBytes][8] -> (MinilockID,Private25519)
mkID pw email = (encodeID pub,priv)
  where
  // XXX wait for cryptol 2.3: priv = SCrypt `{N=2^^17,r=8} (split (blake2s `{nn=32} pw)) email
  priv : Private25519
  priv = SCrypt `{N=2^^1,r=8} (split (blake2s `{nn=32} pw)) email
  // XXX we can't interpret N=2^^17 so this N value is a place holder...
  pub  = Curve25519 priv basePoint25519

// XXX we can not run these tests in the cryptol interpreter, SCrypt is too expensive.
testPass = "some bears eat all the honey in the jar"
testEmail = "example@example.com"

testID : MinilockID
testID = mkFullLengthID "28ZvW9rqRqvqpFTtHnusUntRqrxb4qqZAaNAd3QsqjSsXq"

testID_computed = "28ZvW9rqRqvqpFTtHnusUntRqrxb4qqZAaNAd3QsqjSsXq"  // Computed on deathstar
testPriv_computed =
  [0x12, 0x86, 0xe0, 0x18, 0xc6, 0x68, 0x34, 0x96, 0x09, 0x2e, 0x53,
   0x32, 0x37, 0x76, 0x80, 0x3c, 0x30, 0xb4, 0x75, 0x2d, 0xd7, 0x70,
   0xea, 0xa9, 0x6f, 0x0d, 0xda, 0x25, 0xc7, 0xfe, 0x28, 0x1f]

// Deathstar results:
// ([0x32, 0x38, 0x5a, 0x76, 0x57, 0x39, 0x72, 0x71, 0x52, 0x71, 0x76,
//   0x71, 0x70, 0x46, 0x54, 0x74, 0x48, 0x6e, 0x75, 0x73, 0x55, 0x6e,
//   0x74, 0x52, 0x71, 0x72, 0x78, 0x62, 0x34, 0x71, 0x71, 0x5a, 0x41,
//   0x61, 0x4e, 0x41, 0x64, 0x33, 0x51, 0x73, 0x71, 0x6a, 0x53, 0x73,
//   0x58, 0x71],
//  [0x12, 0x86, 0xe0, 0x18, 0xc6, 0x68, 0x34, 0x96, 0x09, 0x2e, 0x53,
//   0x32, 0x37, 0x76, 0x80, 0x3c, 0x30, 0xb4, 0x75, 0x2d, 0xd7, 0x70,
//   0xea, 0xa9, 0x6f, 0x0d, 0xda, 0x25, 0xc7, 0xfe, 0x28, 0x1f])


// testPriv : Private25519
testPriv = [0x12, 0x86, 0xe0, 0x18, 0xc6, 0x68, 0x34, 0x96, 0x09, 0x2e, 0x53, 0x32, 0x37, 0x76, 0x80, 0x3c, 0x30, 0xb4, 0x75, 0x2d, 0xd7, 0x70,0xea, 0xa9, 0x6f, 0x0d, 0xda, 0x25, 0xc7, 0xfe, 0x28, 0x1f]

testPub = Curve25519 testPriv basePoint25519
property kat_pub_id_eq = testPub == (decodeID testID).1 /\ encodeID testPub == testID /\ testID == testID_computed /\ testPriv == testPriv_computed