File size: 2,804 Bytes
7e9dc27 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 | local HMAC = require("lockbox.mac.hmac");
local Stream = require("lockbox.util.stream");
local Array = require("lockbox.util.array");
local HKDF = function()
local public = {};
local Digest = nil;
local inputKeyMaterial = nil;
local salt = nil;
local info = nil;
local outputLen = nil;
local hashLen = nil;
local secret = nil;
local extract = function()
local res = HMAC()
.setDigest(Digest)
.setKey(salt)
.init()
.update(Stream.fromArray(inputKeyMaterial))
.finish()
.asBytes();
hashLen = #res;
return res;
end
local expand = function(prk)
local iterations = math.ceil(outputLen / hashLen);
local mixin = {};
local results = {};
local remainingBytes = outputLen;
for i = 1, iterations do
local mac = HMAC()
.setDigest(Digest)
.setKey(prk)
.init();
mac.update(Stream.fromArray(mixin));
if info then
mac.update(Stream.fromArray(info));
end
mac.update(Stream.fromArray({ i }));
local stepResult = mac.finish().asBytes();
local stepSize = math.min(remainingBytes, #stepResult);
for j = 1, stepSize do
results[#results + 1] = stepResult[j];
end
mixin = stepResult;
remainingBytes = remainingBytes - stepSize;
end
return results;
end
public.setDigest = function(digestModule)
Digest = digestModule;
return public;
end
public.setInputKeyMaterial = function(ikm)
inputKeyMaterial = ikm;
return public;
end
public.setSalt = function(s)
salt = s;
return public;
end
public.setInfo = function(i)
info = i;
return public;
end
public.setOutputLen = function(len)
outputLen = len;
return public;
end
public.finish = function()
if not salt then
salt = Array.fromHex("0000000000000000000000000000000000000000");
end
local prk = extract(salt, inputKeyMaterial);
secret = expand(prk, info, outputLength);
return public;
end
public.asBytes = function()
return secret;
end
public.asHex = function()
local hex = "";
for i = 1, #secret do
hex = hex .. string.format("%02x", secret[i])
end
return hex;
end
return public;
end
return HKDF;
|