Lua AES Implementation


#1

I’ve recently made a 256 bit AES ECB implementation in pure Lua for use in Roblox. I haven’t verified the output with another AES implementation (if implemented correctly, another library should be able to decrypt cyphertext from my implementation) but it seems to be working as expected.

Do you see any potential problems or possible optimizations?

The full source and usage is found on GitHub but I have included the main script here:
(the tabs were originally 4 spaces wide)

--[[
	Copyright 2019 Tyler Richard Hoyer

	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

		http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
]]

local GF8x2 = {
[0]=0x00,0x02,0x04,0x06,0x08,0x0a,0x0c,0x0e,0x10,0x12,0x14,0x16,0x18,0x1a,0x1c,0x1e,
	0x20,0x22,0x24,0x26,0x28,0x2a,0x2c,0x2e,0x30,0x32,0x34,0x36,0x38,0x3a,0x3c,0x3e,
	0x40,0x42,0x44,0x46,0x48,0x4a,0x4c,0x4e,0x50,0x52,0x54,0x56,0x58,0x5a,0x5c,0x5e,
	0x60,0x62,0x64,0x66,0x68,0x6a,0x6c,0x6e,0x70,0x72,0x74,0x76,0x78,0x7a,0x7c,0x7e,
	0x80,0x82,0x84,0x86,0x88,0x8a,0x8c,0x8e,0x90,0x92,0x94,0x96,0x98,0x9a,0x9c,0x9e,
	0xa0,0xa2,0xa4,0xa6,0xa8,0xaa,0xac,0xae,0xb0,0xb2,0xb4,0xb6,0xb8,0xba,0xbc,0xbe,
	0xc0,0xc2,0xc4,0xc6,0xc8,0xca,0xcc,0xce,0xd0,0xd2,0xd4,0xd6,0xd8,0xda,0xdc,0xde,
	0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xee,0xf0,0xf2,0xf4,0xf6,0xf8,0xfa,0xfc,0xfe,
	0x1b,0x19,0x1f,0x1d,0x13,0x11,0x17,0x15,0x0b,0x09,0x0f,0x0d,0x03,0x01,0x07,0x05,
	0x3b,0x39,0x3f,0x3d,0x33,0x31,0x37,0x35,0x2b,0x29,0x2f,0x2d,0x23,0x21,0x27,0x25,
	0x5b,0x59,0x5f,0x5d,0x53,0x51,0x57,0x55,0x4b,0x49,0x4f,0x4d,0x43,0x41,0x47,0x45,
	0x7b,0x79,0x7f,0x7d,0x73,0x71,0x77,0x75,0x6b,0x69,0x6f,0x6d,0x63,0x61,0x67,0x65,
	0x9b,0x99,0x9f,0x9d,0x93,0x91,0x97,0x95,0x8b,0x89,0x8f,0x8d,0x83,0x81,0x87,0x85,
	0xbb,0xb9,0xbf,0xbd,0xb3,0xb1,0xb7,0xb5,0xab,0xa9,0xaf,0xad,0xa3,0xa1,0xa7,0xa5,
	0xdb,0xd9,0xdf,0xdd,0xd3,0xd1,0xd7,0xd5,0xcb,0xc9,0xcf,0xcd,0xc3,0xc1,0xc7,0xc5,
	0xfb,0xf9,0xff,0xfd,0xf3,0xf1,0xf7,0xf5,0xeb,0xe9,0xef,0xed,0xe3,0xe1,0xe7,0xe5
}

local GF8x3 = {
[0]=0x00,0x03,0x06,0x05,0x0c,0x0f,0x0a,0x09,0x18,0x1b,0x1e,0x1d,0x14,0x17,0x12,0x11,
	0x30,0x33,0x36,0x35,0x3c,0x3f,0x3a,0x39,0x28,0x2b,0x2e,0x2d,0x24,0x27,0x22,0x21,
	0x60,0x63,0x66,0x65,0x6c,0x6f,0x6a,0x69,0x78,0x7b,0x7e,0x7d,0x74,0x77,0x72,0x71,
	0x50,0x53,0x56,0x55,0x5c,0x5f,0x5a,0x59,0x48,0x4b,0x4e,0x4d,0x44,0x47,0x42,0x41,
	0xc0,0xc3,0xc6,0xc5,0xcc,0xcf,0xca,0xc9,0xd8,0xdb,0xde,0xdd,0xd4,0xd7,0xd2,0xd1,
	0xf0,0xf3,0xf6,0xf5,0xfc,0xff,0xfa,0xf9,0xe8,0xeb,0xee,0xed,0xe4,0xe7,0xe2,0xe1,
	0xa0,0xa3,0xa6,0xa5,0xac,0xaf,0xaa,0xa9,0xb8,0xbb,0xbe,0xbd,0xb4,0xb7,0xb2,0xb1,
	0x90,0x93,0x96,0x95,0x9c,0x9f,0x9a,0x99,0x88,0x8b,0x8e,0x8d,0x84,0x87,0x82,0x81,
	0x9b,0x98,0x9d,0x9e,0x97,0x94,0x91,0x92,0x83,0x80,0x85,0x86,0x8f,0x8c,0x89,0x8a,
	0xab,0xa8,0xad,0xae,0xa7,0xa4,0xa1,0xa2,0xb3,0xb0,0xb5,0xb6,0xbf,0xbc,0xb9,0xba,
	0xfb,0xf8,0xfd,0xfe,0xf7,0xf4,0xf1,0xf2,0xe3,0xe0,0xe5,0xe6,0xef,0xec,0xe9,0xea,
	0xcb,0xc8,0xcd,0xce,0xc7,0xc4,0xc1,0xc2,0xd3,0xd0,0xd5,0xd6,0xdf,0xdc,0xd9,0xda,
	0x5b,0x58,0x5d,0x5e,0x57,0x54,0x51,0x52,0x43,0x40,0x45,0x46,0x4f,0x4c,0x49,0x4a,
	0x6b,0x68,0x6d,0x6e,0x67,0x64,0x61,0x62,0x73,0x70,0x75,0x76,0x7f,0x7c,0x79,0x7a,
	0x3b,0x38,0x3d,0x3e,0x37,0x34,0x31,0x32,0x23,0x20,0x25,0x26,0x2f,0x2c,0x29,0x2a,
	0x0b,0x08,0x0d,0x0e,0x07,0x04,0x01,0x02,0x13,0x10,0x15,0x16,0x1f,0x1c,0x19,0x1a
}

local GF8x9 = {
[0]=0x00,0x09,0x12,0x1b,0x24,0x2d,0x36,0x3f,0x48,0x41,0x5a,0x53,0x6c,0x65,0x7e,0x77,
	0x90,0x99,0x82,0x8b,0xb4,0xbd,0xa6,0xaf,0xd8,0xd1,0xca,0xc3,0xfc,0xf5,0xee,0xe7,
	0x3b,0x32,0x29,0x20,0x1f,0x16,0x0d,0x04,0x73,0x7a,0x61,0x68,0x57,0x5e,0x45,0x4c,
	0xab,0xa2,0xb9,0xb0,0x8f,0x86,0x9d,0x94,0xe3,0xea,0xf1,0xf8,0xc7,0xce,0xd5,0xdc,
	0x76,0x7f,0x64,0x6d,0x52,0x5b,0x40,0x49,0x3e,0x37,0x2c,0x25,0x1a,0x13,0x08,0x01,
	0xe6,0xef,0xf4,0xfd,0xc2,0xcb,0xd0,0xd9,0xae,0xa7,0xbc,0xb5,0x8a,0x83,0x98,0x91,
	0x4d,0x44,0x5f,0x56,0x69,0x60,0x7b,0x72,0x05,0x0c,0x17,0x1e,0x21,0x28,0x33,0x3a,
	0xdd,0xd4,0xcf,0xc6,0xf9,0xf0,0xeb,0xe2,0x95,0x9c,0x87,0x8e,0xb1,0xb8,0xa3,0xaa,
	0xec,0xe5,0xfe,0xf7,0xc8,0xc1,0xda,0xd3,0xa4,0xad,0xb6,0xbf,0x80,0x89,0x92,0x9b,
	0x7c,0x75,0x6e,0x67,0x58,0x51,0x4a,0x43,0x34,0x3d,0x26,0x2f,0x10,0x19,0x02,0x0b,
	0xd7,0xde,0xc5,0xcc,0xf3,0xfa,0xe1,0xe8,0x9f,0x96,0x8d,0x84,0xbb,0xb2,0xa9,0xa0,
	0x47,0x4e,0x55,0x5c,0x63,0x6a,0x71,0x78,0x0f,0x06,0x1d,0x14,0x2b,0x22,0x39,0x30,
	0x9a,0x93,0x88,0x81,0xbe,0xb7,0xac,0xa5,0xd2,0xdb,0xc0,0xc9,0xf6,0xff,0xe4,0xed,
	0x0a,0x03,0x18,0x11,0x2e,0x27,0x3c,0x35,0x42,0x4b,0x50,0x59,0x66,0x6f,0x74,0x7d,
	0xa1,0xa8,0xb3,0xba,0x85,0x8c,0x97,0x9e,0xe9,0xe0,0xfb,0xf2,0xcd,0xc4,0xdf,0xd6,
	0x31,0x38,0x23,0x2a,0x15,0x1c,0x07,0x0e,0x79,0x70,0x6b,0x62,0x5d,0x54,0x4f,0x46
}

local GF8x11 = {
[0]=0x00,0x0b,0x16,0x1d,0x2c,0x27,0x3a,0x31,0x58,0x53,0x4e,0x45,0x74,0x7f,0x62,0x69,
	0xb0,0xbb,0xa6,0xad,0x9c,0x97,0x8a,0x81,0xe8,0xe3,0xfe,0xf5,0xc4,0xcf,0xd2,0xd9,
	0x7b,0x70,0x6d,0x66,0x57,0x5c,0x41,0x4a,0x23,0x28,0x35,0x3e,0x0f,0x04,0x19,0x12,
	0xcb,0xc0,0xdd,0xd6,0xe7,0xec,0xf1,0xfa,0x93,0x98,0x85,0x8e,0xbf,0xb4,0xa9,0xa2,
	0xf6,0xfd,0xe0,0xeb,0xda,0xd1,0xcc,0xc7,0xae,0xa5,0xb8,0xb3,0x82,0x89,0x94,0x9f,
	0x46,0x4d,0x50,0x5b,0x6a,0x61,0x7c,0x77,0x1e,0x15,0x08,0x03,0x32,0x39,0x24,0x2f,
	0x8d,0x86,0x9b,0x90,0xa1,0xaa,0xb7,0xbc,0xd5,0xde,0xc3,0xc8,0xf9,0xf2,0xef,0xe4,
	0x3d,0x36,0x2b,0x20,0x11,0x1a,0x07,0x0c,0x65,0x6e,0x73,0x78,0x49,0x42,0x5f,0x54,
	0xf7,0xfc,0xe1,0xea,0xdb,0xd0,0xcd,0xc6,0xaf,0xa4,0xb9,0xb2,0x83,0x88,0x95,0x9e,
	0x47,0x4c,0x51,0x5a,0x6b,0x60,0x7d,0x76,0x1f,0x14,0x09,0x02,0x33,0x38,0x25,0x2e,
	0x8c,0x87,0x9a,0x91,0xa0,0xab,0xb6,0xbd,0xd4,0xdf,0xc2,0xc9,0xf8,0xf3,0xee,0xe5,
	0x3c,0x37,0x2a,0x21,0x10,0x1b,0x06,0x0d,0x64,0x6f,0x72,0x79,0x48,0x43,0x5e,0x55,
	0x01,0x0a,0x17,0x1c,0x2d,0x26,0x3b,0x30,0x59,0x52,0x4f,0x44,0x75,0x7e,0x63,0x68,
	0xb1,0xba,0xa7,0xac,0x9d,0x96,0x8b,0x80,0xe9,0xe2,0xff,0xf4,0xc5,0xce,0xd3,0xd8,
	0x7a,0x71,0x6c,0x67,0x56,0x5d,0x40,0x4b,0x22,0x29,0x34,0x3f,0x0e,0x05,0x18,0x13,
	0xca,0xc1,0xdc,0xd7,0xe6,0xed,0xf0,0xfb,0x92,0x99,0x84,0x8f,0xbe,0xb5,0xa8,0xa3
}

local GF8x13 = {
[0]=0x00,0x0d,0x1a,0x17,0x34,0x39,0x2e,0x23,0x68,0x65,0x72,0x7f,0x5c,0x51,0x46,0x4b,
	0xd0,0xdd,0xca,0xc7,0xe4,0xe9,0xfe,0xf3,0xb8,0xb5,0xa2,0xaf,0x8c,0x81,0x96,0x9b,
	0xbb,0xb6,0xa1,0xac,0x8f,0x82,0x95,0x98,0xd3,0xde,0xc9,0xc4,0xe7,0xea,0xfd,0xf0,
	0x6b,0x66,0x71,0x7c,0x5f,0x52,0x45,0x48,0x03,0x0e,0x19,0x14,0x37,0x3a,0x2d,0x20,
	0x6d,0x60,0x77,0x7a,0x59,0x54,0x43,0x4e,0x05,0x08,0x1f,0x12,0x31,0x3c,0x2b,0x26,
	0xbd,0xb0,0xa7,0xaa,0x89,0x84,0x93,0x9e,0xd5,0xd8,0xcf,0xc2,0xe1,0xec,0xfb,0xf6,
	0xd6,0xdb,0xcc,0xc1,0xe2,0xef,0xf8,0xf5,0xbe,0xb3,0xa4,0xa9,0x8a,0x87,0x90,0x9d,
	0x06,0x0b,0x1c,0x11,0x32,0x3f,0x28,0x25,0x6e,0x63,0x74,0x79,0x5a,0x57,0x40,0x4d,
	0xda,0xd7,0xc0,0xcd,0xee,0xe3,0xf4,0xf9,0xb2,0xbf,0xa8,0xa5,0x86,0x8b,0x9c,0x91,
	0x0a,0x07,0x10,0x1d,0x3e,0x33,0x24,0x29,0x62,0x6f,0x78,0x75,0x56,0x5b,0x4c,0x41,
	0x61,0x6c,0x7b,0x76,0x55,0x58,0x4f,0x42,0x09,0x04,0x13,0x1e,0x3d,0x30,0x27,0x2a,
	0xb1,0xbc,0xab,0xa6,0x85,0x88,0x9f,0x92,0xd9,0xd4,0xc3,0xce,0xed,0xe0,0xf7,0xfa,
	0xb7,0xba,0xad,0xa0,0x83,0x8e,0x99,0x94,0xdf,0xd2,0xc5,0xc8,0xeb,0xe6,0xf1,0xfc,
	0x67,0x6a,0x7d,0x70,0x53,0x5e,0x49,0x44,0x0f,0x02,0x15,0x18,0x3b,0x36,0x21,0x2c,
	0x0c,0x01,0x16,0x1b,0x38,0x35,0x22,0x2f,0x64,0x69,0x7e,0x73,0x50,0x5d,0x4a,0x47,
	0xdc,0xd1,0xc6,0xcb,0xe8,0xe5,0xf2,0xff,0xb4,0xb9,0xae,0xa3,0x80,0x8d,0x9a,0x97
}

local GF8x14 = {
[0]=0x00,0x0e,0x1c,0x12,0x38,0x36,0x24,0x2a,0x70,0x7e,0x6c,0x62,0x48,0x46,0x54,0x5a,
	0xe0,0xee,0xfc,0xf2,0xd8,0xd6,0xc4,0xca,0x90,0x9e,0x8c,0x82,0xa8,0xa6,0xb4,0xba,
	0xdb,0xd5,0xc7,0xc9,0xe3,0xed,0xff,0xf1,0xab,0xa5,0xb7,0xb9,0x93,0x9d,0x8f,0x81,
	0x3b,0x35,0x27,0x29,0x03,0x0d,0x1f,0x11,0x4b,0x45,0x57,0x59,0x73,0x7d,0x6f,0x61,
	0xad,0xa3,0xb1,0xbf,0x95,0x9b,0x89,0x87,0xdd,0xd3,0xc1,0xcf,0xe5,0xeb,0xf9,0xf7,
	0x4d,0x43,0x51,0x5f,0x75,0x7b,0x69,0x67,0x3d,0x33,0x21,0x2f,0x05,0x0b,0x19,0x17,
	0x76,0x78,0x6a,0x64,0x4e,0x40,0x52,0x5c,0x06,0x08,0x1a,0x14,0x3e,0x30,0x22,0x2c,
	0x96,0x98,0x8a,0x84,0xae,0xa0,0xb2,0xbc,0xe6,0xe8,0xfa,0xf4,0xde,0xd0,0xc2,0xcc,
	0x41,0x4f,0x5d,0x53,0x79,0x77,0x65,0x6b,0x31,0x3f,0x2d,0x23,0x09,0x07,0x15,0x1b,
	0xa1,0xaf,0xbd,0xb3,0x99,0x97,0x85,0x8b,0xd1,0xdf,0xcd,0xc3,0xe9,0xe7,0xf5,0xfb,
	0x9a,0x94,0x86,0x88,0xa2,0xac,0xbe,0xb0,0xea,0xe4,0xf6,0xf8,0xd2,0xdc,0xce,0xc0,
	0x7a,0x74,0x66,0x68,0x42,0x4c,0x5e,0x50,0x0a,0x04,0x16,0x18,0x32,0x3c,0x2e,0x20,
	0xec,0xe2,0xf0,0xfe,0xd4,0xda,0xc8,0xc6,0x9c,0x92,0x80,0x8e,0xa4,0xaa,0xb8,0xb6,
	0x0c,0x02,0x10,0x1e,0x34,0x3a,0x28,0x26,0x7c,0x72,0x60,0x6e,0x44,0x4a,0x58,0x56,
	0x37,0x39,0x2b,0x25,0x0f,0x01,0x13,0x1d,0x47,0x49,0x5b,0x55,0x7f,0x71,0x63,0x6d,
	0xd7,0xd9,0xcb,0xc5,0xef,0xe1,0xf3,0xfd,0xa7,0xa9,0xbb,0xb5,0x9f,0x91,0x83,0x8d
}

local s = {
[0]=0x63,0x7C,0x77,0x7B,0xF2,0x6B,0x6F,0xC5,0x30,0x01,0x67,0x2B,0xFE,0xD7,0xAB,0x76,
	0xCA,0x82,0xC9,0x7D,0xFA,0x59,0x47,0xF0,0xAD,0xD4,0xA2,0xAF,0x9C,0xA4,0x72,0xC0,
	0xB7,0xFD,0x93,0x26,0x36,0x3F,0xF7,0xCC,0x34,0xA5,0xE5,0xF1,0x71,0xD8,0x31,0x15,
	0x04,0xC7,0x23,0xC3,0x18,0x96,0x05,0x9A,0x07,0x12,0x80,0xE2,0xEB,0x27,0xB2,0x75,
	0x09,0x83,0x2C,0x1A,0x1B,0x6E,0x5A,0xA0,0x52,0x3B,0xD6,0xB3,0x29,0xE3,0x2F,0x84,
	0x53,0xD1,0x00,0xED,0x20,0xFC,0xB1,0x5B,0x6A,0xCB,0xBE,0x39,0x4A,0x4C,0x58,0xCF,
	0xD0,0xEF,0xAA,0xFB,0x43,0x4D,0x33,0x85,0x45,0xF9,0x02,0x7F,0x50,0x3C,0x9F,0xA8,
	0x51,0xA3,0x40,0x8F,0x92,0x9D,0x38,0xF5,0xBC,0xB6,0xDA,0x21,0x10,0xFF,0xF3,0xD2,
	0xCD,0x0C,0x13,0xEC,0x5F,0x97,0x44,0x17,0xC4,0xA7,0x7E,0x3D,0x64,0x5D,0x19,0x73,
	0x60,0x81,0x4F,0xDC,0x22,0x2A,0x90,0x88,0x46,0xEE,0xB8,0x14,0xDE,0x5E,0x0B,0xDB,
	0xE0,0x32,0x3A,0x0A,0x49,0x06,0x24,0x5C,0xC2,0xD3,0xAC,0x62,0x91,0x95,0xE4,0x79,
	0xE7,0xC8,0x37,0x6D,0x8D,0xD5,0x4E,0xA9,0x6C,0x56,0xF4,0xEA,0x65,0x7A,0xAE,0x08,
	0xBA,0x78,0x25,0x2E,0x1C,0xA6,0xB4,0xC6,0xE8,0xDD,0x74,0x1F,0x4B,0xBD,0x8B,0x8A,
	0x70,0x3E,0xB5,0x66,0x48,0x03,0xF6,0x0E,0x61,0x35,0x57,0xB9,0x86,0xC1,0x1D,0x9E,
	0xE1,0xF8,0x98,0x11,0x69,0xD9,0x8E,0x94,0x9B,0x1E,0x87,0xE9,0xCE,0x55,0x28,0xDF,
	0x8C,0xA1,0x89,0x0D,0xBF,0xE6,0x42,0x68,0x41,0x99,0x2D,0x0F,0xB0,0x54,0xBB,0x16
}

local si = {
[0]=0x52,0x09,0x6A,0xD5,0x30,0x36,0xA5,0x38,0xBF,0x40,0xA3,0x9E,0x81,0xF3,0xD7,0xFB,
	0x7C,0xE3,0x39,0x82,0x9B,0x2F,0xFF,0x87,0x34,0x8E,0x43,0x44,0xC4,0xDE,0xE9,0xCB,
	0x54,0x7B,0x94,0x32,0xA6,0xC2,0x23,0x3D,0xEE,0x4C,0x95,0x0B,0x42,0xFA,0xC3,0x4E,
	0x08,0x2E,0xA1,0x66,0x28,0xD9,0x24,0xB2,0x76,0x5B,0xA2,0x49,0x6D,0x8B,0xD1,0x25,
	0x72,0xF8,0xF6,0x64,0x86,0x68,0x98,0x16,0xD4,0xA4,0x5C,0xCC,0x5D,0x65,0xB6,0x92,
	0x6C,0x70,0x48,0x50,0xFD,0xED,0xB9,0xDA,0x5E,0x15,0x46,0x57,0xA7,0x8D,0x9D,0x84,
	0x90,0xD8,0xAB,0x00,0x8C,0xBC,0xD3,0x0A,0xF7,0xE4,0x58,0x05,0xB8,0xB3,0x45,0x06,
	0xD0,0x2C,0x1E,0x8F,0xCA,0x3F,0x0F,0x02,0xC1,0xAF,0xBD,0x03,0x01,0x13,0x8A,0x6B,
	0x3A,0x91,0x11,0x41,0x4F,0x67,0xDC,0xEA,0x97,0xF2,0xCF,0xCE,0xF0,0xB4,0xE6,0x73,
	0x96,0xAC,0x74,0x22,0xE7,0xAD,0x35,0x85,0xE2,0xF9,0x37,0xE8,0x1C,0x75,0xDF,0x6E,
	0x47,0xF1,0x1A,0x71,0x1D,0x29,0xC5,0x89,0x6F,0xB7,0x62,0x0E,0xAA,0x18,0xBE,0x1B,
	0xFC,0x56,0x3E,0x4B,0xC6,0xD2,0x79,0x20,0x9A,0xDB,0xC0,0xFE,0x78,0xCD,0x5A,0xF4,
	0x1F,0xDD,0xA8,0x33,0x88,0x07,0xC7,0x31,0xB1,0x12,0x10,0x59,0x27,0x80,0xEC,0x5F,
	0x60,0x51,0x7F,0xA9,0x19,0xB5,0x4A,0x0D,0x2D,0xE5,0x7A,0x9F,0x93,0xC9,0x9C,0xEF,
	0xA0,0xE0,0x3B,0x4D,0xAE,0x2A,0xF5,0xB0,0xC8,0xEB,0xBB,0x3C,0x83,0x53,0x99,0x61,
	0x17,0x2B,0x04,0x7E,0xBA,0x77,0xD6,0x26,0xE1,0x69,0x14,0x63,0x55,0x21,0x0C,0x7D
}

local rcon = {
	0x8d,0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0x1b,0x36,0x6c,0xd8,0xab,0x4d,0x9a,
	0x2f,0x5e,0xbc,0x63,0xc6,0x97,0x35,0x6a,0xd4,0xb3,0x7d,0xfa,0xef,0xc5,0x91,0x39,
	0x72,0xe4,0xd3,0xbd,0x61,0xc2,0x9f,0x25,0x4a,0x94,0x33,0x66,0xcc,0x83,0x1d,0x3a,
	0x74,0xe8,0xcb,0x8d,0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0x1b,0x36,0x6c,0xd8,
	0xab,0x4d,0x9a,0x2f,0x5e,0xbc,0x63,0xc6,0x97,0x35,0x6a,0xd4,0xb3,0x7d,0xfa,0xef,
	0xc5,0x91,0x39,0x72,0xe4,0xd3,0xbd,0x61,0xc2,0x9f,0x25,0x4a,0x94,0x33,0x66,0xcc,
	0x83,0x1d,0x3a,0x74,0xe8,0xcb,0x8d,0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80,0x1b,
	0x36,0x6c,0xd8,0xab,0x4d,0x9a,0x2f,0x5e,0xbc,0x63,0xc6,0x97,0x35,0x6a,0xd4,0xb3,
	0x7d,0xfa,0xef,0xc5,0x91,0x39,0x72,0xe4,0xd3,0xbd,0x61,0xc2,0x9f,0x25,0x4a,0x94,
	0x33,0x66,0xcc,0x83,0x1d,0x3a,0x74,0xe8,0xcb,0x8d,0x01,0x02,0x04,0x08,0x10,0x20,
	0x40,0x80,0x1b,0x36,0x6c,0xd8,0xab,0x4d,0x9a,0x2f,0x5e,0xbc,0x63,0xc6,0x97,0x35,
	0x6a,0xd4,0xb3,0x7d,0xfa,0xef,0xc5,0x91,0x39,0x72,0xe4,0xd3,0xbd,0x61,0xc2,0x9f,
	0x25,0x4a,0x94,0x33,0x66,0xcc,0x83,0x1d,0x3a,0x74,0xe8,0xcb,0x8d,0x01,0x02,0x04,
	0x08,0x10,0x20,0x40,0x80,0x1b,0x36,0x6c,0xd8,0xab,0x4d,0x9a,0x2f,0x5e,0xbc,0x63,
	0xc6,0x97,0x35,0x6a,0xd4,0xb3,0x7d,0xfa,0xef,0xc5,0x91,0x39,0x72,0xe4,0xd3,0xbd,
	0x61,0xc2,0x9f,0x25,0x4a,0x94,0x33,0x66,0xcc,0x83,0x1d,0x3a,0x74,0xe8,0xcb,0x8d
}

local xor4 = {
[0]=0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,
	1,0,3,2,5,4,7,6,9,8,11,10,13,12,15,14,
	2,3,0,1,6,7,4,5,10,11,8,9,14,15,12,13,
	3,2,1,0,7,6,5,4,11,10,9,8,15,14,13,12,
	4,5,6,7,0,1,2,3,12,13,14,15,8,9,10,11,
	5,4,7,6,1,0,3,2,13,12,15,14,9,8,11,10,
	6,7,4,5,2,3,0,1,14,15,12,13,10,11,8,9,
	7,6,5,4,3,2,1,0,15,14,13,12,11,10,9,8,
	8,9,10,11,12,13,14,15,0,1,2,3,4,5,6,7,
	9,8,11,10,13,12,15,14,1,0,3,2,5,4,7,6,
	10,11,8,9,14,15,12,13,2,3,0,1,6,7,4,5,
	11,10,9,8,15,14,13,12,3,2,1,0,7,6,5,4,
	12,13,14,15,8,9,10,11,4,5,6,7,0,1,2,3,
	13,12,15,14,9,8,11,10,5,4,7,6,1,0,3,2,
	14,15,12,13,10,11,8,9,6,7,4,5,2,3,0,1,
	15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0,
}

local function xor8(a, b)
	local al = a % 16
	local bl = b % 16
	return 16 * xor4[a - al + (b - bl) / 16] + xor4[16 * al + bl]
end

local function addRoundKey(state, key)
	for i, byte in next, state do
		state[i] = xor8(byte, key[i])
	end
end

local function subBytes(state, s_box)
	for i, byte in next, state do
		state[i] = s_box[byte]
	end
end

local function shiftRows(state)
	state[5], state[6], state[7], state[8] =
	state[6], state[7], state[8], state[5]

	state[9], state[10], state[11], state[12] =
	state[11], state[12], state[9], state[10]

	state[13], state[14], state[15], state[16] =
	state[16], state[13], state[14], state[15]
end

local function inv_shiftRows(state)
	state[6], state[7], state[8], state[5] =
	state[5], state[6], state[7], state[8]

	state[11], state[12], state[9], state[10] =
	state[9], state[10], state[11], state[12]

	state[16], state[13], state[14], state[15] =
	state[13], state[14], state[15], state[16]
end

local function mixColumns(state)
	for cur = 1, 4 do
		local a, b, c, d = state[cur], state[cur + 4], state[cur + 8], state[cur + 12]
		state[cur +  0] = xor8(xor8(xor8(GF8x2[a], GF8x3[b]), c), d)
		state[cur +  4] = xor8(xor8(xor8(a, GF8x2[b]), GF8x3[c]), d)
		state[cur +  8] = xor8(xor8(xor8(a, b), GF8x2[c]), GF8x3[d])
		state[cur + 12] = xor8(xor8(xor8(GF8x3[a], b), c), GF8x2[d])
	end
end

local function inv_mixColumns(state)
	for cur = 1, 4 do
		local a, b, c, d = state[cur], state[cur + 4], state[cur + 8], state[cur + 12]
		state[cur +  0] = xor8(xor8(xor8(GF8x14[a], GF8x11[b]), GF8x13[c]), GF8x9[d])
		state[cur +  4] = xor8(xor8(xor8(GF8x9[a], GF8x14[b]), GF8x11[c]), GF8x13[d])
		state[cur +  8] = xor8(xor8(xor8(GF8x13[a], GF8x9[b]), GF8x14[c]), GF8x11[d])
		state[cur + 12] = xor8(xor8(xor8(GF8x11[a], GF8x13[b]), GF8x9[c]), GF8x14[d])
	end
end

-- 256-bit key constants
local n = 32 -- number of bytes in the 256-bit encryption key
local b = 240 -- number of bytes in 15 128-bit round keys
local function schedule256(key)
	local expanded = {}
	for c = 0, n do
		local byte = key % 256
		expanded[c] = byte
		key = (key - byte) / 256
	end

	local i = 1
	local c = n
	local t1 = expanded[1]
	local t2 = expanded[2]
	local t3 = expanded[3]
	local t4 = expanded[4]
	while c < b do
		t1, t2, t3, t4 = xor8(rcon[i], s[t2]), s[t3], s[t4], s[t1]
		i = i + 1

		for _ = 1, 4 do
			c = c + 1
			t1 = xor8(t1, expanded[c - n])
			expanded[c] = t1

			c = c + 1
			t2 = xor8(t2, expanded[c - n])
			expanded[c] = t2

			c = c + 1
			t3 = xor8(t3, expanded[c - n])
			expanded[c] = t3

			c = c + 1
			t4 = xor8(t4, expanded[c - n])
			expanded[c] = t4
		end

		t1 = s[t1]
		t2 = s[t2]
		t3 = s[t3]
		t4 = s[t4]

		for _ = 1, 4 do
			c = c + 1
			t1 = xor8(t1, expanded[c - n])
			expanded[c] = t1

			c = c + 1
			t2 = xor8(t2, expanded[c - n])
			expanded[c] = t2

			c = c + 1
			t3 = xor8(t3, expanded[c - n])
			expanded[c] = t3

			c = c + 1
			t4 = xor8(t4, expanded[c - n])
			expanded[c] = t4
		end
	end

	local roundKeys = {}
	for round = 0, 14 do
		local roundKey = {}
		for byte = 1, 16 do
			roundKey[byte] = expanded[round * 16 + byte]
		end
		roundKeys[round] = roundKey
	end
	return roundKeys
end

local function chunks(text, i)
	local first = i * 16 + 1
	if first > #text then
		return
	end
	i = i + 1

	local chunk = {text:byte(first, first + 15)}
	for j = #chunk + 1, 16 do
		chunk[j] = 0
	end

	return i, chunk
end

local function encrypt(state, roundKeys)
	addRoundKey(state, roundKeys[0])
	for round = 1, 13 do
		subBytes(state, s)
		shiftRows(state)
		mixColumns(state)
		addRoundKey(state, roundKeys[round])
	end
	subBytes(state, s)
	shiftRows(state)
	addRoundKey(state, roundKeys[14])
end

local function decrypt(state, roundKeys)
	addRoundKey(state, roundKeys[14])
	inv_shiftRows(state)
	subBytes(state, si)
	for round = 13, 1, -1 do
		addRoundKey(state, roundKeys[round])
		inv_mixColumns(state)
		inv_shiftRows(state)
		subBytes(state, si)
	end
	addRoundKey(state, roundKeys[0])
end

local function ECB_256(method, key, originaltext)
	local text = {}
	local roundKeys = schedule256(key)
	for chunk, state in chunks, originaltext, 0 do
		method(state, roundKeys)
		text[chunk] = string.char(unpack(state))
	end
	return table.concat(text)
end

return {
	encrypt = encrypt;
	decrypt = decrypt;
	ECB_256 = ECB_256;
}

#2

What’s the performance like?

I once tried to implement a standard algorithm (MD5) in Lua and with all the bit operations that Lua 5.1 does not do, it was unusably slow.


#3

It takes about 1.25 ms per a 16 byte block.

Here is a microprofiler dump and the .rbxl place used to generate it:
microprofile-20190210-140759.html (267.6 KB)
AES Test.rbxl (22.8 KB)

About 1/2 of the time is spend in xor… another fourth or more seems to be the calling overhead to xor. I’ll see if inlining xor helps. (btw the version used in that test file is updated: I exposed the 256 bit key scheduler so that it only needs to be called when the key changes rather than every call ECB.


#4

AES seems a little intense for Roblox, but its still really cool. I made my own simple but secure symmetric encryption method on roblox that I call “StratEncrypt”.

Do you think you could pull off a secure asymmetric encryption in Roblox? If so that would be amazing!


#5

This would be far faster if Roblox had a native bitwise operations library - there already exists a easy to implement library for doing this, and I think its been suggested on DevForum before, so meh.

Also, lookup tables aren’t particularly quick in Lua… you might want to try finding something else other then xor8.


#6

I Agree. With Lua 5.1 it should take 7 lines of C to implement xor. One for the function header, two lines for an assertion of the type of each argument, one line for the xor itself and pushing it onto the Lua stack, a return value of 1, a closing bracket, and a single line to add that function to the environment with a name. Backporting the Lua 5.2 bit32 library or 5.3 bitwise operators would also be a good option. They are super basic operations and there isn’t much of a reason not to support them.

OpenSSL uses 5 lookup tables to combine the subByte and mixColumns steps into a single lookup with a couple 32 bit xors. I may split those 5 tables into 40 so I can do 32 simple 4-bit xor lookups without shifting instead of 4 32-bit xors (which requires division, mods, and multiplication). Options, options… I have some other things I need to take care of first though.


I should be able to pull off an implementation of ECDH. Were you thinking of using it for signing? That would be difficult if so. X25519 looks like a good option. Maybe once I find time.