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crypto_box: fix keypair, implement seal/seal_open

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Secret Key is a random nonce, and public key is a point on elliptic
curve.

`crypto_box_seal`/`crypto_box_seal_open` are implemented using existing
primitives and newly exported `core_hsalsa20` in `xsalsa20`
This commit is contained in:
Fedor Indutny 2019-08-13 08:00:27 -07:00 committed by Emil Bay
parent 49587c3d7f
commit 4e42b942a5
1 changed files with 54 additions and 2 deletions
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56
index.js
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@ -1,5 +1,7 @@
'use strict';
var xsalsa20 = require('xsalsa20')
// Based on https://github.com/dchest/tweetnacl-js/blob/6dcbcaf5f5cbfd313f2dcfe763db35c828c8ff5b/nacl-fast.js.
var sodium = module.exports
@ -1739,8 +1741,52 @@ function crypto_secretbox_open_easy(msg, box, n, k) {
function crypto_box_keypair(pk, sk) {
check(pk, crypto_box_PUBLICKEYBYTES)
check(sk, crypto_box_SECRETKEYBYTES)
randombytes(pk, 32);
return crypto_scalarmult_base(sk, pk);
randombytes(sk, 32)
return crypto_scalarmult_base(pk, sk)
}
function crypto_box_seal(c, m, pk) {
check(c, crypto_box_SEALBYTES + m.length)
check(pk, crypto_box_PUBLICKEYBYTES)
var epk = c.subarray(0, crypto_box_PUBLICKEYBYTES)
var esk = new Uint8Array(crypto_box_SECRETKEYBYTES)
crypto_box_keypair(epk, esk)
var n = new Uint8Array(crypto_box_NONCEBYTES)
sodium.crypto_generichash_batch(n, [ epk, pk ])
var s = new Uint8Array(crypto_box_PUBLICKEYBYTES)
crypto_scalarmult(s, esk, pk)
var k = new Uint8Array(crypto_box_BEFORENMBYTES)
var zero = new Uint8Array(16)
xsalsa20.core_hsalsa20(k, zero, s, xsalsa20.SIGMA)
crypto_secretbox_easy(c.subarray(epk.length), m, n, k)
cleanup(esk)
}
function crypto_box_seal_open(m, c, pk, sk) {
check(c, crypto_box_SEALBYTES)
check(m, c.length - crypto_box_SEALBYTES)
check(pk, crypto_box_PUBLICKEYBYTES)
check(sk, crypto_box_SECRETKEYBYTES)
var epk = c.subarray(0, crypto_box_PUBLICKEYBYTES)
var n = new Uint8Array(crypto_box_NONCEBYTES)
sodium.crypto_generichash_batch(n, [ epk, pk ])
var s = new Uint8Array(crypto_box_PUBLICKEYBYTES)
crypto_scalarmult(s, sk, epk)
var k = new Uint8Array(crypto_box_BEFORENMBYTES)
var zero = new Uint8Array(16)
xsalsa20.core_hsalsa20(k, zero, s, xsalsa20.SIGMA)
return crypto_secretbox_open_easy(m, c.subarray(epk.length), n, k)
}
var crypto_secretbox_KEYBYTES = 32,
@ -1755,6 +1801,8 @@ var crypto_secretbox_KEYBYTES = 32,
crypto_box_NONCEBYTES = crypto_secretbox_NONCEBYTES,
crypto_box_ZEROBYTES = crypto_secretbox_ZEROBYTES,
crypto_box_BOXZEROBYTES = crypto_secretbox_BOXZEROBYTES,
crypto_box_SEALBYTES = 48,
crypto_box_BEFORENMBYTES = 32,
crypto_sign_BYTES = 64,
crypto_sign_PUBLICKEYBYTES = 32,
crypto_sign_SECRETKEYBYTES = 64,
@ -1797,7 +1845,11 @@ sodium.crypto_secretbox_open_detached = crypto_secretbox_open_detached
sodium.crypto_box_PUBLICKEYBYTES = crypto_box_PUBLICKEYBYTES
sodium.crypto_box_SECRETKEYBYTES = crypto_box_SECRETKEYBYTES
sodium.crypto_box_SEALBYTES = crypto_box_SEALBYTES
sodium.crypto_box_BEFORENMBYTES = crypto_box_BEFORENMBYTES
sodium.crypto_box_keypair = crypto_box_keypair
sodium.crypto_box_seal = crypto_box_seal
sodium.crypto_box_seal_open = crypto_box_seal_open
function cleanup(arr) {
for (var i = 0; i < arr.length; i++) arr[i] = 0;