sodium-javascript/crypto_kdf.js

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var assert = require('nanoassert')
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var randombytes_buf = require('./randombytes').randombytes_buf
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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) {
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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')
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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)
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var outlen = Math.min(subkey.length, module.exports.crypto_kdf_BYTES_MAX)
blake2b(outlen, key, salt, ctx_padded, true)
.final(subkey)
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}
module.exports.crypto_kdf_keygen = function crypto_kdf_keygen (out) {
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assert(out.length >= module.exports.crypto_kdf_KEYBYTES, 'out.length must be crypto_kdf_KEYBYTES')
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randombytes_buf(out.subarray(0, module.exports.crypto_kdf_KEYBYTES))
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}