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-rw-r--r--util/hmac.lua67
1 files changed, 67 insertions, 0 deletions
diff --git a/util/hmac.lua b/util/hmac.lua
new file mode 100644
index 00000000..b3098380
--- /dev/null
+++ b/util/hmac.lua
@@ -0,0 +1,67 @@
+local hashes = require "util.hashes"
+local xor = require "bit".bxor
+
+module "hmac"
+
+local function arraystr(array)
+ t = {}
+ for i = 1,table.getn(array) do
+ table.insert(t, string.char(array[i]))
+ end
+
+ return table.concat(t)
+end
+
+--[[
+key
+ the key to use in the hash
+message
+ the message to hash
+hash
+ the hash function
+blocksize
+ the blocksize for the hash function in bytes
+hex
+ return raw hash or hexadecimal string
+--]]
+function hmac(key, message, hash, blocksize, hex)
+ local opad = {}
+ local ipad = {}
+
+ for i = 1,blocksize do
+ opad[i] = 0x5c
+ ipad[i] = 0x36
+ end
+
+ if #key > blocksize then
+ key = hash(key)
+ end
+
+ for i = 1,#key do
+ ipad[i] = xor(ipad[i],key:sub(i,i):byte())
+ opad[i] = xor(opad[i],key:sub(i,i):byte())
+ end
+
+ opad = arraystr(opad)
+ ipad = arraystr(ipad)
+
+ if hex then
+ return hash(opad..hash(ipad..message), true)
+ else
+ return hash(opad..hash(ipad..message))
+ end
+end
+
+function md5(key, message, hex)
+ return hmac(key, message, hashes.md5, 64, hex)
+end
+
+function sha1(key, message, hex)
+ return hmac(key, message, hashes.sha1, 64, hex)
+end
+
+function sha256(key, message, hex)
+ return hmac(key, message, hashes.sha256, 64, hex)
+end
+
+return _M