sodium-javascript/crypto_kdf.js
Jim Pick 5159d68fa9 In kdf, truncate key before passing to blake to match sodium-native behaviour
Currently, sodium-native and sodium-javascript are returning different
hashes. The code in hyperdrive passes a 64 byte secret key to the kdf,
but only 32 bytes are used by the native version, but all 64 bytes are
used in the javascript version. As a result, hyperdrive secret keys
can't be imported/exported across the two sodium implementations.

https://gist.github.com/jimpick/3e869522eddaad77ac1bc9e64f36e1a7
2018-03-03 17:24:12 +00:00

40 lines
1.5 KiB
JavaScript

var assert = require('nanoassert')
var randombytes_buf = require('./randombytes').randombytes_buf
var blake2b = require('blake2b')
module.exports.crypto_kdf_PRIMITIVE = 'blake2b'
module.exports.crypto_kdf_BYTES_MIN = 16
module.exports.crypto_kdf_BYTES_MAX = 64
module.exports.crypto_kdf_CONTEXTBYTES = 8
module.exports.crypto_kdf_KEYBYTES = 64
function STORE64_LE(dest, int) {
var mul = 1
var i = 0
dest[0] = int & 0xFF
while (++i < 8 && (mul *= 0x100)) {
dest[i] = (int / mul) & 0xFF
}
}
module.exports.crypto_kdf_derive_from_key = function crypto_kdf_derive_from_key (subkey, subkey_id, ctx, key) {
assert(subkey.length >= module.exports.crypto_kdf_BYTES_MIN, 'subkey must be at least crypto_kdf_BYTES_MIN')
assert(subkey_id >= 0 && subkey_id <= 0x1fffffffffffff, 'subkey_id must be safe integer')
assert(ctx.length >= module.exports.crypto_kdf_CONTEXTBYTES, 'context must be at least crypto_kdf_CONTEXTBYTES')
var ctx_padded = new Uint8Array(blake2b.PERSONALBYTES)
var salt = new Uint8Array(blake2b.SALTBYTES)
ctx_padded.set(ctx, 0, module.exports.crypto_kdf_CONTEXTBYTES)
STORE64_LE(salt, subkey_id)
var outlen = Math.min(subkey.length, module.exports.crypto_kdf_BYTES_MAX)
blake2b(outlen, key.slice(0, blake2b.KEYBYTES), salt, ctx_padded, true)
.final(subkey)
}
module.exports.crypto_kdf_keygen = function crypto_kdf_keygen (out) {
assert(out.length >= module.exports.crypto_kdf_KEYBYTES, 'out.length must be crypto_kdf_KEYBYTES')
randombytes_buf(out.subarray(0, module.exports.crypto_kdf_KEYBYTES))
}