use origin input key by default

lib/resty/aes.lua

@@ -125,50 +125,75 @@ cipher = function (size, _cipher)
 end
 _M.cipher = cipher
 
-function _M.new(self, key, salt, _cipher, _hash, hash_rounds)
+
+local options = {
+    default = 0x01,
+    key_without_gen = 0x02
+    -- may add other things like padding mode; or use bit 'or/and' operation for combined option
+}
+_M.options = options
+
+function _M.new(self, key, salt, _cipher, _hash, hash_rounds, option)
     local encrypt_ctx = ffi_new(ctx_ptr_type)
     local decrypt_ctx = ffi_new(ctx_ptr_type)
     local _cipher = _cipher or cipher()
     local _hash = _hash or hash.md5
     local hash_rounds = hash_rounds or 1
+    local option = option or options.default
     local _cipherLength = _cipher.size/8
     local gen_key = ffi_new("unsigned char[?]",_cipherLength)
     local gen_iv = ffi_new("unsigned char[?]",_cipherLength)
 
-    if type(_hash) == "table" then
-        if not _hash.iv or #_hash.iv ~= 16 then
-          return nil, "bad iv"
-        end
+    if option == options.default then
+        if type(_hash) == "table" then
+            if not _hash.iv or #_hash.iv ~= 16 then
+              return nil, "bad iv"
+            end
+
+            if _hash.method then
+                local tmp_key = _hash.method(key)
 
-        if _hash.method then
-            local tmp_key = _hash.method(key)
+                if #tmp_key ~= _cipherLength then
+                    return nil, "bad key length"
+                end
 
-            if #tmp_key ~= _cipherLength then
+                ffi_copy(gen_key, tmp_key, _cipherLength)
+
+            elseif #key ~= _cipherLength then
                 return nil, "bad key length"
-            end
 
-            ffi_copy(gen_key, tmp_key, _cipherLength)
+            else
+                ffi_copy(gen_key, key, _cipherLength)
+            end
 
-        elseif #key ~= _cipherLength then
-            return nil, "bad key length"
+            ffi_copy(gen_iv, _hash.iv, 16)
 
         else
-            ffi_copy(gen_key, key, _cipherLength)
-        end
+            if salt and #salt ~= 8 then
+                return nil, "salt must be 8 characters or nil"
+            end
 
-        ffi_copy(gen_iv, _hash.iv, 16)
+            if C.EVP_BytesToKey(_cipher.method, _hash, salt, key, #key,
+                                hash_rounds, gen_key, gen_iv)
+                ~= _cipherLength
+            then
+                return nil
+            end
+        end
 
-    else
-        if salt and #salt ~= 8 then
-            return nil, "salt must be 8 characters or nil"
+    elseif option == options.key_without_gen then
+        -- use origin key
+        if not key then
+            return nil, "key is nil!"
         end
 
-        if C.EVP_BytesToKey(_cipher.method, _hash, salt, key, #key,
-                            hash_rounds, gen_key, gen_iv)
-            ~= _cipherLength
-        then
-            return nil
+        if #key > _cipherLength then
+            return nil, "key too long"
         end
+
+        -- note it's key padding not data padding, and it use zero padding only;
+        key = key..string.rep("\0", _cipherLength - #key)
+        ffi_copy(gen_key, key, _cipherLength)
     end
 
     C.EVP_CIPHER_CTX_init(encrypt_ctx)

t/aes.t

@@ -293,3 +293,24 @@ failed to new: bad iv
 --- no_error_log
 [error]
 
+=== TEST 11: AES key_without_gen hello
+--- http_config eval: $::HttpConfig
+--- config
+    location /t {
+        content_by_lua '
+            local aes = require "resty.aes"
+            local str = require "resty.string"
+            local aes_default = aes:new("secret", nil, nil, nil, nil, aes.options.key_without_gen)
+            local encrypted = aes_default:encrypt("hello")
+            ngx.say("AES-128 CBC MD5: ", str.to_hex(encrypted))
+            local decrypted = aes_default:decrypt(encrypted)
+            ngx.say(decrypted == "hello")
+        ';
+    }
+--- request
+GET /t
+--- response_body
+AES-128 CBC MD5: c290e8b6de4ea5773414e019fe7f17a3
+true
+--- no_error_log
+[error]