AES Strong Encryption

BETA!

The code/project on this page is currently considered to be in beta, and should not be used in a production environment until proper testing has been completed

AES Encryption

The AES encryption standard is a cryptographically secure and widely supported symmetric key, stream encryption scheme. It takes a strong key and applies it to an input in a series of "rounds" to a 16-byte chunk of data (the state). The resulting cipher is so thoroughly different from the original that it is considered cryptographically secure. Indeed, there are as yet no reported cases of AES encryption being successfully broken except through side channel attacks, essentially using other available data or means to get at the original (not a fault of the algorithm itself).

For more information regarding the algorithm you may view the Wikipedia page.

Implementation

Usage

The usual restrictions on open-source software apply to the following code; namely there are very few! You may use the provided code in any project you wish so long as you give credit to the script author (Haravikk Mistral) for providing this code as a base, you are also asked to please provide a link to this wiki article.

Description

This implementation is a fairly basic one, it utilises a 16-byte wide state for effective encryption for 128, 192, and 256-bit keys only. This script accepts messages larger than 16-bytes long, and applies a segment number to them to reduce the chances of repeated segments producing the same cipher block. Data is zero-padded to ensure that it can be divided into 16-byte segments, with the last byte of the (unencrypted) data providing the number of padding bits added to the data.

This script provides methods for serialising/unserialising byte-data to and from base64 and hexadecimal alphabets. Support for additional alphabets (e.g a base 256 one) is easily added as the functions (lslAESBytesToString() and lslAESStringToBytes()) are designed to be flexible.

The implementation is based on the freely available open-source C/C++ implementation at Hoozi. The implementation therefore is mostly a straight port of the AES algorithm itself, with the aforementioned adjustments to make it more secure.

Future Development

Future development will be mostly performance-centric, aiming to further increase speed and reduce the memory footprint (allowing support for larger messages). This will be ongoing. Investigations will also be made into improving compatibility with widely available AES implementations in use.

Originally planned was to modify the algorithm for use for the WHIRLPOOL hashing function, however this has higher memory requirements (precomputed data is approximately 64 times larger!). However, a hashing function using the already implemented algorithm may be adapted easily.

An exact port to PHP is also planned, for full compatibility with the LSL version.

Thanks

Thanks to Strife Onizuka for work in optimising/testing the initial implementation.

Mono-LSL Code

The following code is provided as an encryption "client". That is, you can simply send it link-messages in order to encrypt your messages. You must first of all "prime" it with a key to use for encryption/decryption, this is very fast so you may swap keys in and out as required without much penalty. Once the engine is "primed" you may encrypt/decrypt as many messages as you wish, up to a size of 1.5kb, larger messages will be refused as they risk a stack/heap collision.

Link messages are identified by the integer argument by adding a command to the base constant. Here is a summary of the messages values, and the replies you will get:

Commands

Command	Code	Type	Description
Prime	33792	Hex	Primes engine with a key transmitted as a hexadecimal string. Invalid size will return an error.
	33793	Base64	Primes engine with a key transmitted as a base64 string (note that base64 uses blocks of width 6-bits, only use for keys that are a factor of six (i.e - 192 bits). Invalid size will return an error.
Encrypt	36864	Hex	Encrypts a hexadecimal string, returning the cipher-text as a padded hexadecimal string
	36865	Base64	Encrypts a base64 strings, returning the cipher-text as a padded base64 string
Decrypt	49152	Hex	Decrypts a hexadecimal string, removing the padding added by encryption and returning the decrypted hexadecimal data
	49153	Base64	Decrypts a base64 string, removing the padding added by encryption and returning the decrypted base64 data

Replies

Reply	Code	Type	Description
ERROR	65536	string	An error occurred, described by the string-data of the reply
Prime	66560	void	Indicates the AES engine was primed successfully using the hex key it was given
	65561	void	Indicates the AES engine was primed successfully using the base64 key it was given
Encrypt	69632	Hex	Contains a hexadecimal representation of the encrypted data
	69633	Base64	Contains a base64 representation of the encrypted data
Decrypt	81920	Hex	Contains a hexadecimal representation of the decrypted data
	81921	Base64	Contains a base64 representation of the decrypted data

Code

Below is the code. It will only compile within Mono at the moment due to the memory requirements. You may edit the constants used for communication at the top. It should be noted that for speed, this implementation uses a set of 16 integers as the state, and unrolls all loops into a set of instructions for speed. Also, data is processed as a list of integers rather than bytes to conserve memory, and where relevant a bit-header is attached to the top of a list to aid with serialisation.

<lsl>integer LSLAES_COMMS_BASE = 32768; integer LSLAES_COMMS_REPLY_BASE = 65536;

integer LSLAES_COMMS_BASE64 = 1; integer LSLAES_COMMS_PRIME = 1024; integer LSLAES_COMMS_ENCRYPT = 4096; integer LSLAES_COMMS_DECRYPT = 16384;

// Defines how "wide" the range of comms values are integer LSLAES_COMMS_WIDTH = 32767;

// Refuse any data longer than this many characters integer LSLAES_MAX_SIZE = 1536;

string LSLAES_HEX_CHARS = "0123456789ABCDEF"; string LSLAES_BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

// The inverted Rijndael SBox, values in the state are substituted with these list LSLAES_SBOX_INVERTED = [

   0x52096ad5, 0x3036a538, 0xbf40a39e, 0x81f3d7fb, 0x7ce33982, 
   0x9b2fff87, 0x348e4344, 0xc4dee9cb, 0x547b9432, 0xa6c2233d, 
   0xee4c950b, 0x42fac34e, 0x082ea166, 0x28d924b2, 0x765ba249, 
   0x6d8bd125, 0x72f8f664, 0x86689816, 0xd4a45ccc, 0x5d65b692, 
   0x6c704850, 0xfdedb9da, 0x5e154657, 0xa78d9d84, 0x90d8ab00, 
   0x8cbcd30a, 0xf7e45805, 0xb8b34506, 0xd02c1e8f, 0xca3f0f02, 
   0xc1afbd03, 0x01138a6b, 0x3a911141, 0x4f67dcea, 0x97f2cfce, 
   0xf0b4e673, 0x96ac7422, 0xe7ad3585, 0xe2f937e8, 0x1c75df6e, 
   0x47f11a71, 0x1d29c589, 0x6fb7620e, 0xaa18be1b, 0xfc563e4b, 
   0xc6d27920, 0x9adbc0fe, 0x78cd5af4, 0x1fdda833, 0x8807c731, 
   0xb1121059, 0x2780ec5f, 0x60517fa9, 0x19b54a0d, 0x2de57a9f, 
   0x93c99cef, 0xa0e03b4d, 0xae2af5b0, 0xc8ebbb3c, 0x83539961, 
   0x172b047e, 0xba77d626, 0xe1691463, 0x55210c7d

];

integer lslAESSBoxInvertedCached = -1; integer lslAESSBoxInvertedCache = 0;

// Treats the above list as a byte-array, retrieving the desired byte value. integer lslAESGetSBoxInvertedByte(integer n) {

   integer b = n % 4;  // Byte within integer
           n /= 4;     // Integer
   b = 3 - b;

   if (lslAESSBoxInvertedCached == n) n = lslAESSBoxInvertedCache;
   else {
       lslAESSBoxInvertedCached = n;
       lslAESSBoxInvertedCache = llList2Integer(LSLAES_SBOX_INVERTED, n);
   }
   return (lslAESSBoxInvertedCache >> (b << 3)) & 0xFF;

}

// The Rijndael SBox, values in the state are substituted with these list LSLAES_SBOX = [

   0x637c777b, 0xf26b6fc5, 0x3001672b, 0xfed7ab76, 0xca82c97d, 
   0xfa5947f0, 0xadd4a2af, 0x9ca472c0, 0xb7fd9326, 0x363ff7cc, 
   0x34a5e5f1, 0x71d83115, 0x04c723c3, 0x1896059a, 0x071280e2,
   0xeb27b275, 0x09832c1a, 0x1b6e5aa0, 0x523bd6b3, 0x29e32f84, 
   0x53d100ed, 0x20fcb15b, 0x6acbbe39, 0x4a4c58cf, 0xd0efaafb, 
   0x434d3385, 0x45f9027f, 0x503c9fa8, 0x51a3408f, 0x929d38f5, 
   0xbcb6da21, 0x10fff3d2, 0xcd0c13ec, 0x5f974417, 0xc4a77e3d, 
   0x645d1973, 0x60814fdc, 0x222a9088, 0x46eeb814, 0xde5e0bdb, 
   0xe0323a0a, 0x4906245c, 0xc2d3ac62, 0x9195e479, 0xe7c8376d, 
   0x8dd54ea9, 0x6c56f4ea, 0x657aae08, 0xba78252e, 0x1ca6b4c6, 
   0xe8dd741f, 0x4bbd8b8a, 0x703eb566, 0x4803f60e, 0x613557b9, 
   0x86c11d9e, 0xe1f89811, 0x69d98e94, 0x9b1e87e9, 0xce5528df, 
   0x8ca1890d, 0xbfe64268, 0x41992d0f, 0xb054bb16

];

integer lslAESSBoxCached = -1; integer lslAESSBoxCache = 0;

// Treats the above list as a byte-array, retrieving the desired byte value. integer lslAESGetSBoxByte(integer n) {

   integer b = n % 4;  // Byte within integer
           n /= 4;     // Integer
   b = 3 - b;

   if (lslAESSBoxCached == n) n = lslAESSBoxCache;
   else {
       lslAESSBoxCached = n;
       lslAESSBoxCache = llList2Integer(LSLAES_SBOX, n);
   }
   return (lslAESSBoxCache >> (b << 3)) & 0xFF;

}

// Used for the actual encryption, generated from Key list lslAESRoundKey = []; // The number of rounds to perform (bigger key == more rounds) integer lslAESRounds = 0;

// The following are used for the state instead of a list integer lslAESStateX0Y0 = 0; integer lslAESStateX0Y1 = 0; integer lslAESStateX0Y2 = 0; integer lslAESStateX0Y3 = 0; integer lslAESStateX1Y0 = 0; integer lslAESStateX1Y1 = 0; integer lslAESStateX1Y2 = 0; integer lslAESStateX1Y3 = 0; integer lslAESStateX2Y0 = 0; integer lslAESStateX2Y1 = 0; integer lslAESStateX2Y2 = 0; integer lslAESStateX2Y3 = 0; integer lslAESStateX3Y0 = 0; integer lslAESStateX3Y1 = 0; integer lslAESStateX3Y2 = 0; integer lslAESStateX3Y3 = 0;

//##########################################################################// // HIGH-LEVEL FUNCTIONS // //##########################################################################// // The following functions are the ones to call to encrypt/decrypt // //##########################################################################// // Decrypts a list of integers into a list of decrypted integers. Padding is // automatically removed as-per the method used by lslAESCipher. list lslAESInvertCipher(list data) {

   // Preserve the bit-count header for output
   integer bits = llList2Integer(data, 0);
   data = llList2List((data = []) + data, 1, -1);
   
   integer i = 0; integer j = 0;
   integer l = (data != []);
   list output = [];
   while (l > 0) {
       // Copy some input into state variables
       j = llList2Integer(data, 0);
       lslAESStateX0Y0 = ((j >> 24) & 0xFF);
       lslAESStateX0Y1 = ((j >> 16) & 0xFF);
       lslAESStateX0Y2 = ((j >> 8)  & 0xFF);
       lslAESStateX0Y3 = (j         & 0xFF);
       j = llList2Integer(data, 1);
       lslAESStateX1Y0 = ((j >> 24) & 0xFF);
       lslAESStateX1Y1 = ((j >> 16) & 0xFF);
       lslAESStateX1Y2 = ((j >> 8)  & 0xFF);
       lslAESStateX1Y3 = (j         & 0xFF);
       j = llList2Integer(data, 2);
       lslAESStateX2Y0 = ((j >> 24) & 0xFF);
       lslAESStateX2Y1 = ((j >> 16) & 0xFF);
       lslAESStateX2Y2 = ((j >> 8)  & 0xFF);
       lslAESStateX2Y3 = (j         & 0xFF);
       j = llList2Integer(data, 3);
       lslAESStateX3Y0 = ((j >> 24) & 0xFF);
       lslAESStateX3Y1 = ((j >> 16) & 0xFF);
       lslAESStateX3Y2 = ((j >> 8)  & 0xFF);
       lslAESStateX3Y3 = (j         & 0xFF);
       
       // Add last round key before rounds begin
       lslAESAddRoundKey(lslAESRounds);
       
       // There will be Rounds - 1 identical rounds
       j = lslAESRounds - 1;
       while (j > 0) {
           lslAESInvertShiftRows();
           lslAESInvertSubBytes();
           lslAESAddRoundKey(j--);
           lslAESInvertMixColumns();
       }
       
       // The last round requires no mixing
       lslAESInvertShiftRows();
       lslAESInvertSubBytes();
       lslAESAddRoundKey(0);
       
       if (l > 4) 
           data = llList2List((data = []) + data, 4, -1);
       else data = [];
       l -= 4;
       
       // XOR with i
       output = (output = []) + output + [
           ((lslAESStateX0Y0 ^ i) << 24) | ((lslAESStateX0Y1 ^ i) << 16) | 
               ((lslAESStateX0Y2 ^ i) << 8) | (lslAESStateX0Y3 ^ i),
           ((lslAESStateX1Y0 ^ i) << 24) | ((lslAESStateX1Y1 ^ i) << 16) | 
               ((lslAESStateX1Y2 ^ i) << 8) | (lslAESStateX1Y3 ^ i),
           ((lslAESStateX2Y0 ^ i) << 24) | ((lslAESStateX2Y1 ^ i) << 16) | 
               ((lslAESStateX2Y2 ^ i) << 8) | (lslAESStateX2Y3 ^ i),
           ((lslAESStateX3Y0 ^ i) << 24) | ((lslAESStateX3Y1 ^ i) << 16) | 
               ((lslAESStateX3Y2 ^ i) << 8) | (lslAESStateX3Y3 ^ i)
       ];
       i = (++i % 256);
   }
   
   // Remove padding bytes and add bit-header
   j = llList2Integer(output, -1) & 0xFF;
   return [bits - j] + 
       llList2List((output = []) + output, 0, -((j / 32) + 1));

}

// Encrypts a list of integers into a list of encrypted integers. Input is // padded using the number of required pad entries. Thus, after decryption // you will need to use the last byte of the decrypted string, to find how // many bytes in total were added as padding, so you may trim them. e.g - if // the byte is of value 12 then a total of 12 bytes were added, including the // one you read. Padding is ALWAYS added, even if the input is correctly // divisible (in which case a full-block of padding is added). list lslAESCipher(list data) {

   // Preserve the bit-count header for output
   integer bits = llList2Integer(data, 0);
   data = llList2List((data = []) + data, 1, -1);
   
   // Add padding integers
   integer l = data != [];
   integer j = 128 - (bits % 128);
   
   integer t = j / 32;
   integer i = 1;
   while (i < t) data = (data = []) + data + [++i];
   data = (data = []) + data + [j];

   list output = [bits + j];
   
   i = 0;
   l = (data != []);
   while (l > 0) {
       // Copy some input into state variables, and XOR with i
       j = llList2Integer(data, 0);
       lslAESStateX0Y0 = ((j >> 24) & 0xFF) ^ i;
       lslAESStateX0Y1 = ((j >> 16) & 0xFF) ^ i;
       lslAESStateX0Y2 = ((j >> 8)  & 0xFF) ^ i;
       lslAESStateX0Y3 = (j         & 0xFF) ^ i;
       j = llList2Integer(data, 1);
       lslAESStateX1Y0 = ((j >> 24) & 0xFF) ^ i;
       lslAESStateX1Y1 = ((j >> 16) & 0xFF) ^ i;
       lslAESStateX1Y2 = ((j >> 8)  & 0xFF) ^ i;
       lslAESStateX1Y3 = (j         & 0xFF) ^ i;
       j = llList2Integer(data, 2);
       lslAESStateX2Y0 = ((j >> 24) & 0xFF) ^ i;
       lslAESStateX2Y1 = ((j >> 16) & 0xFF) ^ i;
       lslAESStateX2Y2 = ((j >> 8)  & 0xFF) ^ i;
       lslAESStateX2Y3 = (j         & 0xFF) ^ i;
       j = llList2Integer(data, 3);
       lslAESStateX3Y0 = ((j >> 24) & 0xFF) ^ i;
       lslAESStateX3Y1 = ((j >> 16) & 0xFF) ^ i;
       lslAESStateX3Y2 = ((j >> 8)  & 0xFF) ^ i;
       lslAESStateX3Y3 = (j         & 0xFF) ^ i;
       
       // Add first round-key before starting rounds
       lslAESAddRoundKey(0);
       
       // There will be Rounds iterations, the first 
       // Rounds - 1 are identical.
       j = 1;
       while (j < lslAESRounds) {
           lslAESSubBytes();
           lslAESShiftRows();
           lslAESMixColumns();
           lslAESAddRoundKey(j++);
       }
       
       // The last column performs no mix
       lslAESSubBytes();
       lslAESShiftRows();
       lslAESAddRoundKey(lslAESRounds);
       
       if (l > 4) 
           data = llList2List((data = []) + data, 4, -1);
       else data = [];
       l -= 4;
       
       output = (output = []) + output + [
           (lslAESStateX0Y0 << 24) | (lslAESStateX0Y1 << 16) | 
               (lslAESStateX0Y2 << 8) | lslAESStateX0Y3,
           (lslAESStateX1Y0 << 24) | (lslAESStateX1Y1 << 16) | 
               (lslAESStateX1Y2 << 8) | lslAESStateX1Y3,
           (lslAESStateX2Y0 << 24) | (lslAESStateX2Y1 << 16) | 
               (lslAESStateX2Y2 << 8) | lslAESStateX2Y3,
           (lslAESStateX3Y0 << 24) | (lslAESStateX3Y1 << 16) | 
               (lslAESStateX3Y2 << 8) | lslAESStateX3Y3
       ];
       i = (++i % 256);
   }
   
   return (output = []) + output;

}

//##########################################################################// // PROCESSING FUNCTIONS // //##########################################################################// // The following functions are used to process data that is being // // encrypted or decrypted. // //##########################################################################// // XORs the value with RoundKey values lslAESAddRoundKey(integer round) {

   round = round << 2;
   
   integer t = llList2Integer(lslAESRoundKey, round);
   lslAESStateX0Y0 = lslAESStateX0Y0 ^ ((t >> 24) & 0xFF);
   lslAESStateX0Y1 = lslAESStateX0Y1 ^ ((t >> 16) & 0xFF);
   lslAESStateX0Y2 = lslAESStateX0Y2 ^ ((t >> 8)  & 0xFF);
   lslAESStateX0Y3 = lslAESStateX0Y3 ^ (t         & 0xFF);
   
   t = llList2Integer(lslAESRoundKey, ++round);
   lslAESStateX1Y0 = lslAESStateX1Y0 ^ ((t >> 24) & 0xFF);
   lslAESStateX1Y1 = lslAESStateX1Y1 ^ ((t >> 16) & 0xFF);
   lslAESStateX1Y2 = lslAESStateX1Y2 ^ ((t >> 8)  & 0xFF);
   lslAESStateX1Y3 = lslAESStateX1Y3 ^ (t         & 0xFF);
   
   t = llList2Integer(lslAESRoundKey, ++round);
   lslAESStateX2Y0 = lslAESStateX2Y0 ^ ((t >> 24) & 0xFF);
   lslAESStateX2Y1 = lslAESStateX2Y1 ^ ((t >> 16) & 0xFF);
   lslAESStateX2Y2 = lslAESStateX2Y2 ^ ((t >> 8)  & 0xFF);
   lslAESStateX2Y3 = lslAESStateX2Y3 ^ (t         & 0xFF);
   
   t = llList2Integer(lslAESRoundKey, ++round);
   lslAESStateX3Y0 = lslAESStateX3Y0 ^ ((t >> 24) & 0xFF);
   lslAESStateX3Y1 = lslAESStateX3Y1 ^ ((t >> 16) & 0xFF);
   lslAESStateX3Y2 = lslAESStateX3Y2 ^ ((t >> 8)  & 0xFF);
   lslAESStateX3Y3 = lslAESStateX3Y3 ^ (t         & 0xFF);

}

// Performs a substitution using SBox lslAESSubBytes() {

   lslAESStateX0Y0 = lslAESGetSBoxByte(lslAESStateX0Y0);
   lslAESStateX0Y1 = lslAESGetSBoxByte(lslAESStateX0Y1);
   lslAESStateX0Y2 = lslAESGetSBoxByte(lslAESStateX0Y2);
   lslAESStateX0Y3 = lslAESGetSBoxByte(lslAESStateX0Y3);
   lslAESStateX1Y0 = lslAESGetSBoxByte(lslAESStateX1Y0);
   lslAESStateX1Y1 = lslAESGetSBoxByte(lslAESStateX1Y1);
   lslAESStateX1Y2 = lslAESGetSBoxByte(lslAESStateX1Y2);
   lslAESStateX1Y3 = lslAESGetSBoxByte(lslAESStateX1Y3);
   lslAESStateX2Y0 = lslAESGetSBoxByte(lslAESStateX2Y0);
   lslAESStateX2Y1 = lslAESGetSBoxByte(lslAESStateX2Y1);
   lslAESStateX2Y2 = lslAESGetSBoxByte(lslAESStateX2Y2);
   lslAESStateX2Y3 = lslAESGetSBoxByte(lslAESStateX2Y3);
   lslAESStateX3Y0 = lslAESGetSBoxByte(lslAESStateX3Y0);
   lslAESStateX3Y1 = lslAESGetSBoxByte(lslAESStateX3Y1);
   lslAESStateX3Y2 = lslAESGetSBoxByte(lslAESStateX3Y2);
   lslAESStateX3Y3 = lslAESGetSBoxByte(lslAESStateX3Y3);

}

// Performs a substition using SBoxInverted lslAESInvertSubBytes() {

   lslAESStateX0Y0 = lslAESGetSBoxInvertedByte(lslAESStateX0Y0);
   lslAESStateX0Y1 = lslAESGetSBoxInvertedByte(lslAESStateX0Y1);
   lslAESStateX0Y2 = lslAESGetSBoxInvertedByte(lslAESStateX0Y2);
   lslAESStateX0Y3 = lslAESGetSBoxInvertedByte(lslAESStateX0Y3);
   lslAESStateX1Y0 = lslAESGetSBoxInvertedByte(lslAESStateX1Y0);
   lslAESStateX1Y1 = lslAESGetSBoxInvertedByte(lslAESStateX1Y1);
   lslAESStateX1Y2 = lslAESGetSBoxInvertedByte(lslAESStateX1Y2);
   lslAESStateX1Y3 = lslAESGetSBoxInvertedByte(lslAESStateX1Y3);
   lslAESStateX2Y0 = lslAESGetSBoxInvertedByte(lslAESStateX2Y0);
   lslAESStateX2Y1 = lslAESGetSBoxInvertedByte(lslAESStateX2Y1);
   lslAESStateX2Y2 = lslAESGetSBoxInvertedByte(lslAESStateX2Y2);
   lslAESStateX2Y3 = lslAESGetSBoxInvertedByte(lslAESStateX2Y3);
   lslAESStateX3Y0 = lslAESGetSBoxInvertedByte(lslAESStateX3Y0);
   lslAESStateX3Y1 = lslAESGetSBoxInvertedByte(lslAESStateX3Y1);
   lslAESStateX3Y2 = lslAESGetSBoxInvertedByte(lslAESStateX3Y2);
   lslAESStateX3Y3 = lslAESGetSBoxInvertedByte(lslAESStateX3Y3);

}

// Performs row shifts lslAESShiftRows() {

   integer t = 0;
   
   // Rotate first row 1 columns to left
   t = lslAESStateX1Y0;
   lslAESStateX1Y0 = lslAESStateX1Y1;
   lslAESStateX1Y1 = lslAESStateX1Y2;
   lslAESStateX1Y2 = lslAESStateX1Y3;
   lslAESStateX1Y3 = t;
   
   // Rotate second row 2 columns to left
   t = lslAESStateX2Y0;
   lslAESStateX2Y0 = lslAESStateX2Y2;
   lslAESStateX2Y2 = t;
   
   t = lslAESStateX2Y1;
   lslAESStateX2Y1 = lslAESStateX2Y3;
   lslAESStateX2Y3 = t;
   
   // Rotate third row 3 columns to left
   t = lslAESStateX3Y0;
   lslAESStateX3Y0 = lslAESStateX3Y3;
   lslAESStateX3Y3 = lslAESStateX3Y2;
   lslAESStateX3Y2 = lslAESStateX3Y1;
   lslAESStateX3Y1 = t;

}

// Undoes a set of row shifts lslAESInvertShiftRows() {

   integer t = 0;
   
   // Rotate first row 1 columns to right
   t = lslAESStateX1Y3;
   lslAESStateX1Y3 = lslAESStateX1Y2;
   lslAESStateX1Y2 = lslAESStateX1Y1;
   lslAESStateX1Y1 = lslAESStateX1Y0;
   lslAESStateX1Y0 = t;
   
   // Rotate second row 2 columns to right
   t = lslAESStateX2Y0;
   lslAESStateX2Y0 = lslAESStateX2Y2;
   lslAESStateX2Y2 = t;
   
   t = lslAESStateX2Y1;
   lslAESStateX2Y1 = lslAESStateX2Y3;
   lslAESStateX2Y3 = t;
   
   // Rotate third row 3 columns to right
   t = lslAESStateX3Y0;
   lslAESStateX3Y0 = lslAESStateX3Y1;
   lslAESStateX3Y1 = lslAESStateX3Y2;
   lslAESStateX3Y2 = lslAESStateX3Y3;
   lslAESStateX3Y3 = t;

}

// Mixes columns of the state lslAESMixColumns() {

   integer t = lslAESStateX0Y0;
   integer t1 = lslAESStateX0Y0 ^ lslAESStateX1Y0 ^ 
       lslAESStateX2Y0 ^ lslAESStateX3Y0;
   
   integer t2 = lslAESXTimes(lslAESStateX0Y0 ^ lslAESStateX1Y0);
   lslAESStateX0Y0 = lslAESStateX0Y0 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX1Y0 ^ lslAESStateX2Y0);
   lslAESStateX1Y0 = lslAESStateX1Y0 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX2Y0 ^ lslAESStateX3Y0);
   lslAESStateX2Y0 = lslAESStateX2Y0 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX3Y0 ^ t);
   lslAESStateX3Y0 = lslAESStateX3Y0 ^ t2 ^ t1;
   
   t = lslAESStateX0Y1;
   t1 = lslAESStateX0Y1 ^ lslAESStateX1Y1 ^ lslAESStateX2Y1 ^ lslAESStateX3Y1;
   
   t2 = lslAESXTimes(lslAESStateX0Y1 ^ lslAESStateX1Y1);
   lslAESStateX0Y1 = lslAESStateX0Y1 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX1Y1 ^ lslAESStateX2Y1);
   lslAESStateX1Y1 = lslAESStateX1Y1 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX2Y1 ^ lslAESStateX3Y1);
   lslAESStateX2Y1 = lslAESStateX2Y1 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX3Y1 ^ t);
   lslAESStateX3Y1 = lslAESStateX3Y1 ^ t2 ^ t1;
   
   t = lslAESStateX0Y2;
   t1 = lslAESStateX0Y2 ^ lslAESStateX1Y2 ^ lslAESStateX2Y2 ^ lslAESStateX3Y2;
   
   t2 = lslAESXTimes(lslAESStateX0Y2 ^ lslAESStateX1Y2);
   lslAESStateX0Y2 = lslAESStateX0Y2 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX1Y2 ^ lslAESStateX2Y2);
   lslAESStateX1Y2 = lslAESStateX1Y2 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX2Y2 ^ lslAESStateX3Y2);
   lslAESStateX2Y2 = lslAESStateX2Y2 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX3Y2 ^ t);
   lslAESStateX3Y2 = lslAESStateX3Y2 ^ t2 ^ t1;
   
   t = lslAESStateX0Y3;
   t1 = lslAESStateX0Y3 ^ lslAESStateX1Y3 ^ lslAESStateX2Y3 ^ lslAESStateX3Y3;
   
   t2 = lslAESXTimes(lslAESStateX0Y3 ^ lslAESStateX1Y3);
   lslAESStateX0Y3 = lslAESStateX0Y3 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX1Y3 ^ lslAESStateX2Y3);
   lslAESStateX1Y3 = lslAESStateX1Y3 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX2Y3 ^ lslAESStateX3Y3);
   lslAESStateX2Y3 = lslAESStateX2Y3 ^ t2 ^ t1;
   
   t2 = lslAESXTimes(lslAESStateX3Y3 ^ t);
   lslAESStateX3Y3 = lslAESStateX3Y3 ^ t2 ^ t1;

}

// Used when column mixing integer lslAESXTimes(integer x) {

   return ((x << 1) ^ (((x >> 7) & 1) * 0x1b)) & 0xFF;

}

// Used when column mixing integer lslAESMultiply(integer x, integer y) {

   integer xT  = lslAESXTimes(x);
   integer xT2 = lslAESXTimes(xT);
   integer xT3 = lslAESXTimes(xT2);
   
   return (((y & 1) * x) ^ (((y >> 1) & 1) * xT) ^ 
           (((y >> 2) & 1) * xT2) ^ (((y >> 3) & 1) * xT3) ^ 
           (((y >> 4) & 1) * lslAESXTimes(xT3))) & 0xFF;

}

// Try to understand this at your own peril! lslAESInvertMixColumns() {

   integer a = lslAESStateX0Y0;
   integer b = lslAESStateX1Y0;
   integer c = lslAESStateX2Y0;
   integer d = lslAESStateX3Y0;
   
   lslAESStateX0Y0 = lslAESMultiply(a, 0x0e) ^ lslAESMultiply(b, 0x0b) ^ 
       lslAESMultiply(c, 0x0d) ^ lslAESMultiply(d, 0x09);
   lslAESStateX1Y0 = lslAESMultiply(a, 0x09) ^ lslAESMultiply(b, 0x0e) ^ 
       lslAESMultiply(c, 0x0b) ^ lslAESMultiply(d, 0x0d);
   lslAESStateX2Y0 = lslAESMultiply(a, 0x0d) ^ lslAESMultiply(b, 0x09) ^ 
       lslAESMultiply(c, 0x0e) ^ lslAESMultiply(d, 0x0b);
   lslAESStateX3Y0 = lslAESMultiply(a, 0x0b) ^ lslAESMultiply(b, 0x0d) ^ 
       lslAESMultiply(c, 0x09) ^ lslAESMultiply(d, 0x0e);
       
   a = lslAESStateX0Y1;
   b = lslAESStateX1Y1;
   c = lslAESStateX2Y1;
   d = lslAESStateX3Y1;
   
   lslAESStateX0Y1 = lslAESMultiply(a, 0x0e) ^ lslAESMultiply(b, 0x0b) ^ 
       lslAESMultiply(c, 0x0d) ^ lslAESMultiply(d, 0x09);
   lslAESStateX1Y1 = lslAESMultiply(a, 0x09) ^ lslAESMultiply(b, 0x0e) ^ 
       lslAESMultiply(c, 0x0b) ^ lslAESMultiply(d, 0x0d);
   lslAESStateX2Y1 = lslAESMultiply(a, 0x0d) ^ lslAESMultiply(b, 0x09) ^ 
       lslAESMultiply(c, 0x0e) ^ lslAESMultiply(d, 0x0b);
   lslAESStateX3Y1 = lslAESMultiply(a, 0x0b) ^ lslAESMultiply(b, 0x0d) ^ 
       lslAESMultiply(c, 0x09) ^ lslAESMultiply(d, 0x0e);
       
   a = lslAESStateX0Y2;
   b = lslAESStateX1Y2;
   c = lslAESStateX2Y2;
   d = lslAESStateX3Y2;
   
   lslAESStateX0Y2 = lslAESMultiply(a, 0x0e) ^ lslAESMultiply(b, 0x0b) ^ 
       lslAESMultiply(c, 0x0d) ^ lslAESMultiply(d, 0x09);
   lslAESStateX1Y2 = lslAESMultiply(a, 0x09) ^ lslAESMultiply(b, 0x0e) ^ 
       lslAESMultiply(c, 0x0b) ^ lslAESMultiply(d, 0x0d);
   lslAESStateX2Y2 = lslAESMultiply(a, 0x0d) ^ lslAESMultiply(b, 0x09) ^ 
       lslAESMultiply(c, 0x0e) ^ lslAESMultiply(d, 0x0b);
   lslAESStateX3Y2 = lslAESMultiply(a, 0x0b) ^ lslAESMultiply(b, 0x0d) ^ 
       lslAESMultiply(c, 0x09) ^ lslAESMultiply(d, 0x0e);
       
   a = lslAESStateX0Y3;
   b = lslAESStateX1Y3;
   c = lslAESStateX2Y3;
   d = lslAESStateX3Y3;
   
   lslAESStateX0Y3 = lslAESMultiply(a, 0x0e) ^ lslAESMultiply(b, 0x0b) ^ 
       lslAESMultiply(c, 0x0d) ^ lslAESMultiply(d, 0x09);
   lslAESStateX1Y3 = lslAESMultiply(a, 0x09) ^ lslAESMultiply(b, 0x0e) ^ 
       lslAESMultiply(c, 0x0b) ^ lslAESMultiply(d, 0x0d);
   lslAESStateX2Y3 = lslAESMultiply(a, 0x0d) ^ lslAESMultiply(b, 0x09) ^ 
       lslAESMultiply(c, 0x0e) ^ lslAESMultiply(d, 0x0b);
   lslAESStateX3Y3 = lslAESMultiply(a, 0x0b) ^ lslAESMultiply(b, 0x0d) ^ 
       lslAESMultiply(c, 0x09) ^ lslAESMultiply(d, 0x0e);

}

//##########################################################################// // ENCRYPTION SET-UP FUNCTIONS // //##########################################################################// // The following functions are used to set-up the AES encryption engine // // using the value is Key. // //##########################################################################// // Takes the key bytes provided and sets up the engine ready to encrypt or // decrypt using it. string lslAESKeyExpansion(list keyBytes) {

    // Don't need the bit-count and the first round key is the key itself
   integer len = (
       (
           lslAESRoundKey = llDeleteSubList( // Remove header, copy into rounds
               (lslAESRoundKey = keyBytes = []) + keyBytes, 
               0, 
               0
           )
       ) != []); // Get the length

   // Check that we are within reasonable limits
   if ((len < 4) || (len > 8)) {
       lslAESRoundKey = [];
       return "Invalid key size; must be 128, 192, or 256 bits!";
   }

   // Calculate the number of required rounds
   lslAESRounds = len + 6;
   
   // All others are found from previous keys
   integer i = 0;
   integer x = (len * 3) + 28;

   integer t = llList2Integer(lslAESRoundKey, -1);
   
   do {
       if (!(i % len)) {
           // Rotate by 1, SubWord and Nudge [0x01020408, 0x01020408, 0x1b366cd8]
           t = ((lslAESGetSBoxByte((t >> 16) & 0xFF) ^ 
                    (0x000D8080 >> (7 ^ (i / len)))) << 24) | 
                (lslAESGetSBoxByte((t >>  8) & 0xFF) << 16) | 
                (lslAESGetSBoxByte((t      ) & 0xFF) <<  8) |
                 lslAESGetSBoxByte((t >> 24) & 0xFF);
       } else if ((len > 6) && (i % len) == 4) {
           // SubWord
           t = (lslAESGetSBoxByte((t >> 24) & 0xFF) << 24) | 
               (lslAESGetSBoxByte((t >> 16) & 0xFF) << 16) | 
               (lslAESGetSBoxByte((t >>  8) & 0xFF) <<  8) |
               (lslAESGetSBoxByte((t      ) & 0xFF)      );
       }
       
       // XOR k with four previous RoundKey values And add the new entries, yay!
       lslAESRoundKey = (lslAESRoundKey = []) + lslAESRoundKey + 
           (t = (t ^ llList2Integer(lslAESRoundKey, i)));
   } while ((i = -~i) < x);

   // On success no error message is returned
   return "";

}

//##########################################################################// // SERIALISATION FUNCTIONS // //##########################################################################// // The following functions are used to serialise a string into a list of // // byte data for use as a key, or to encrypt/decrypt. // //##########################################################################// // Load value as integers from a base64 string list lslAESBase64ToBytes(string base64Data) {

   integer x = llSubStringIndex(base64Data, "=");
   if (x > 0) 
       base64Data = llGetSubString(
           (base64Data = "") + base64Data, 
           0, 
           --x
       );
   return lslAESStringToBytes(
       (base64Data = "") + base64Data, 
       6, 
       LSLAES_BASE64_CHARS
   );

}

// Load value as integers from a hex string list lslAESHexToBytes(string hexData) {

   if (llGetSubString(hexData, 0, 1) == "0x") 
       hexData = llGetSubString((hexData = "") + hexData, 2, -1);
   return lslAESStringToBytes(
       (hexData = "") + hexData, 
       4, 
       LSLAES_HEX_CHARS
   );

}

// Loads a string as a list of integers, using the given bit <width> and // appropriate <alphabet> into Key list lslAESStringToBytes(string s, integer width, string alphabet) {

   integer l = llStringLength(s);
   
   list n = [l * width]; // Add bit-length
   integer bitbuf = 0;
   integer adjust = 32;
   
   integer i = 0;
   integer val;
   while (i < l) {
       val = llSubStringIndex(alphabet, llGetSubString(s, i, i));
       if (val < 0) {
           s = "";
           return (n = []) + 
               ["Invalid character at index "+(string)i];
       }

       if ((adjust -= width) <= 0) {
           bitbuf = bitbuf | (val >> -adjust);
           n = (n = []) + n + [bitbuf];
           
           adjust += 32;
           if (adjust < 32) bitbuf = (val << adjust);
           else bitbuf = 0;
       } else bitbuf = bitbuf | (val << adjust);

       ++i;
   }
   
   s = "";
   if (adjust < 32) 
       return (n = []) + n + [bitbuf];
   return (n = []) + n;

}

// Returns a hex string representing integers b, preceeded with "0x". string lslAESBytesToHex(list b) {

   return "0x" + lslAESBytesToString((b = []) + b, 4, LSLAES_HEX_CHARS);

}

// Returns a base64 string representing integers b, with padding equals signs string lslAESBytesToBase64(list b) {

   string s = lslAESBytesToString((b = []) + b, 6, LSLAES_BASE64_CHARS);
   integer l = llStringLength(s) % 3;
   if (l) {
       if (l == 1) return (s = "") + s + "==";
       return (s = "") + s + "=";
   }
   return (s = "") + s;

}

// Outputs integer data from b as characters representing width bits taken from // alphabet string lslAESBytesToString(list b, integer width, string alphabet) {

   integer bits = llList2Integer(b, 0);
   
   integer i = 0;
   integer mask = ~(-1 << width);
   integer shift = 32 - width;
   
   integer available = 0;
   integer prev = 0;
   integer buf;
   integer extra;
   integer value;
   
   string s = "";
   
   @lslAESBytesToStringLoop;
   if((bits -= 32) > -32) {
       available += 32 + (bits * (0 > bits));
       buf = llList2Integer(b, ++i);
       if (available >= width) {
           if (prev) {
               s = (s = "") + s + 
                   llGetSubString(
                       alphabet, 
                       value = (
                           extra | 
                           (
                               (buf >> (shift + prev)) & 
                               ~(-1 << (width - prev))
                           )
                       ), 
                       value
                   );
               buf = buf << (width - prev);
               available -= width;
           }
           while(available >= width) {
               s = (s = "") + s + 
                   llGetSubString(
                       alphabet, 
                       value = ((buf >> shift) & mask),
                       value
                   );
               buf = buf << width;
               available -= width;
           }
           if (prev = available) // Update prev
               extra = (buf >> shift) & mask;
           jump lslAESBytesToStringLoop;
       }
   }
   if(available) {
       mask = -1 << (width - prev);
       return (s = "") + s + 
           llGetSubString(
               alphabet, 
               value = ((extra & mask) | 
                       (
                           (buf >> (shift + prev)) & 
                           ((-1 << (width - available)) ^ mask))
                       ), 
               value
           );
   }
   return (s = "") + s;

}

default {

   link_message(integer x, integer y, string msg, key id) {        
       // Is the message in our range?
       if ((y >= LSLAES_COMMS_BASE) && 
           (y < (LSLAES_COMMS_BASE + LSLAES_COMMS_WIDTH))) {
           y -= LSLAES_COMMS_BASE;
           
           // Is input too large?
           if (llStringLength(msg) > LSLAES_MAX_SIZE) {
               llMessageLinked(
                   x, 
                   LSLAES_COMMS_REPLY_BASE, 
                   (msg = "") + "Input too large!", 
                   id
               );
               return;
           }
           
           // Load the data
           list l = [];
           if (y & LSLAES_COMMS_BASE64) 
               l = lslAESBase64ToBytes((msg = "") + msg);
           else l = lslAESHexToBytes((msg = "") + msg);
           
           // Was the value parsed successfully?
           if (llGetListEntryType(l, 0) != TYPE_INTEGER) {
               llMessageLinked(
                   x,
                   LSLAES_COMMS_REPLY_BASE,
                   llList2String((l = []) + l, 0),
                   id
               );
               return;
           }
           
           if (y & LSLAES_COMMS_PRIME) {
               msg = lslAESKeyExpansion((l = []) + l);
               if (msg == "") y += LSLAES_COMMS_REPLY_BASE;
               else y = LSLAES_COMMS_REPLY_BASE;
               
               llMessageLinked(x, y, (msg = "") + msg, id);
           } else {
               if (y & LSLAES_COMMS_ENCRYPT) 
                   l = lslAESCipher((l = []) + l);
               else if (y & LSLAES_COMMS_DECRYPT) 
                   l = lslAESInvertCipher((l = []) + l);
               else return;
               
               y += LSLAES_COMMS_REPLY_BASE;
               
               if (y & LSLAES_COMMS_BASE64) 
                   msg = lslAESBytesToBase64((l = []) + l);
               else msg = lslAESBytesToHex((l = []) + l);
               
               llMessageLinked(x, y, (msg = "") + msg, id);
           }
       }
   }

}</lsl>

Example use-cases

The following code-snippets contain basic example scripts which demonstrate how to use the AES encryption engine. You may edit these to better fit your code, or use the logic presented to implement it differently.

Encrypt a message

This snippet takes a key and a message store in global variables and encrypts the message using the key. You should NOT use the same key represented, and should avoid using the same key all the time where possible, however, secure key generation is not an aspect of this library.

<lsl>string myKey = "0123456789ABCDEF0123456789ABCDEF"; // 128-bit key in hexadecimal string message = "Hello world! I am a wonderful message awaiting some wonderful encryption!";

default {

   state_entry() { // First prime the engine with a key
       llMessageLinked(
           LINK_THIS, // Change this to wherever your AES engine script is located
           33792, // Prime a hex-key
           myKey,
           llGetKey()
       );
   }

   link_message(integer x, integer y, string msg, key id) {
       if ((y < 65536) || (id != llGetKey())) 
           return; // Ignore other messages

       y -= 65536;
       if (!y) llOwnerSay("ERROR: "+msg);
       else if (y == 1024) state encrypt;
   }

}

state encrypt {

   state_entry() { // Send our message
       llMessageLinked(
           LINK_THIS, // Same as above
           36865, // Encrypt a base64 message
           llStringToBase64(message),
           llGetKey()
       );
   }

   link_message(integer x, integer y, string msg, key id) {
       if ((y < 65536) || (id != llGetKey())) 
           return; // Ignore other messages

       y -= 65536;
       if (!y) llOwnerSay("ERROR: "+msg);
       else if (y == 4097) 
           llOwnerSay("Encrypted = "+msg);
   }

}</lsl>

Decrypt a message

This snippet will take a message encrypted using the above code and decrypt it.

<lsl>string myKey = "0123456789ABCDEF0123456789ABCDEF"; // 128-bit key in hexadecimal string ciphertext = "U/zfhxtVqvtq0vEyN6PPw3g20raPY5avp/T0mS26rlk==";

default {

   state_entry() { // First prime the engine with a key
       llMessageLinked(
           LINK_THIS, // Change this to wherever your AES engine script is located
           33792, // Prime a hex-key
           myKey,
           llGetKey()
       );
   }

   link_message(integer x, integer y, string msg, key id) {
       if ((y < 65536) || (id != llGetKey())) 
           return; // Ignore other messages

       y -= 65536;
       if (!y) llOwnerSay("ERROR: "+msg);
       else if (y == 1024) state decrypt;
   }

}

state decrypt {

   state_entry() { // Send our message
       llMessageLinked(
           LINK_THIS, // Same as above
           49153, // Decrypt a base64 message
           ciphertext,
           llGetKey()
       );
   }

   link_message(integer x, integer y, string msg, key id) {
       if ((y < 65536) || (id != llGetKey())) 
           return; // Ignore other messages

       y -= 65536;
       if (!y) llOwnerSay("ERROR: "+msg);
       else if (y == 16385) 
           llOwnerSay("Decrypted = "+llBase64ToString(msg));
   }

}</lsl>

PHP Code

An equivalent PHP solution is pending, and will be pretty much an exact port of the LSL code.