What is a hexadecimal message type in sending transaction

Technical Discussion
#1

Reading the documentation and data about sending transactions I saw that there are 2 types of messages:

type 1 is plain,
type 2 is secure (encrypted)

Here is the example of transaction with type 1 message I am not sure but I believe this is the transaction with the type 2 message

Now looking at the official NEM wallet it looks like there is also a hexadecimal type:

nem
nem.jpg783×193 21.5 KB

What is this type? I know what hexadecimal means and can guess what it can mean but I would like to see a documentation reference or official explanation.

#2

How can I send a message to another Ethereum address? And how would that user receiving know that its a message? Is there an Ethereum wallet that will show that I sent a message to that address? And what is the max size I can send?

#3

@CryptoInfo you should ask this question on Ethereum forum :wink:

You can’t send directly message/transaction from NEM to Ethereum blockchain right now. If you want send a message from Ethereum to Ethereum address best place is ask on some Ethereum forum.

#4

@nem_curious

Unencrypted message is also send as hexadecimal string to API (mostly is called some UTF8toHEX function as in nanowallet). When you put message:

  • “test” is converted to “74657374” in hex string
  • “1234” is converted to “31323334” in hex string

Hexadecimal message type is a little bit different. User message is already hexadecimal string so it’s no need convert it to hex.
That’s why it allows you to put 2046 (2048 - 2) signs instead 1024bytes (signs) like in simple unencrypted message. Why -2? Because each hexadecimal message has prefix ‘fe’ to tell how it should be decrypted.

Decrypt algorithm (for unencrypted message):
if (it starts with ‘fe’)
remove ‘fe’ from beginning and rest is hexadecimal type message (no need to decrypt hextoutf8)
else
convert hexToUtf8

Example transactions and difference between unencrypted and hexadecimal:

Unencrypted with message “1234” (payload is “31323334”):
http://192.3.61.243:7890/transaction/get?hash=aa655b6c9828b667e64a6194e2e52b2aa715a4fc758de152edc630971a6e6f42

Hexadecimal with message “1234” (payload is “fe1234”):
http://192.3.61.243:7890/transaction/get?hash=40e61876c107a258c3cfcebb54590fe468b5f54f11d032eee133003bdf8c3bf3

So hexadecimal type is designed to send hex string directly (it allows you send more signs because you already sending hex). I guess this is main (only?) reason. @BloodyRookie, @gimre, @Jaguar0625 can confirm or not :slight_smile:

4 Likes
#5

Maybe you could try Interledger to communicate NEM with Ethereum.
Interledger is an open protocol suite for sending payments across different ledgers.

#6

@CryptoBeliever thank you very much for a very good explanation. So if I understood it correctly, all the time I am getting an information about the unencrypted transaction via the API I am getting a “hex encoded string” in a payload which I can ‘unhex’.

If the transaction payload starts with ‘fe’, no need to unencode it.

When I see a transaction in the blockexplorer, the message is already unencoded and the actual payload is 77656c636f6d6520746f207368656c74657264616f21.

One question is left. Is it possible to have a payload which starts with ‘fe’ which is not a hexadecimal string? If I want to send a string like “þÿ” it will be encoded to “feff” and then it will not be clear whether it is hexadecimal “ff” was sent or my “þÿ”.

As a suggestion, it would be nice to add this information to a documentation.

#7

Yes, that is the reason.

1 Like
#8

@nem_curious
Yes payload returned by API is “hex encoded string”. If starts with ‘fe’ you just remove it and it’s decded + it’s type hexadecimal. In explorer it’s already decoded.

About þ it will be no problem in nanowallet because nano first use rstr2utf8 function which “Converts a raw javascript string into a string of single byte characters using utf8 encoding.” So it changes þ to two single bytes characters.

If it would no rstr2utf8 then indeed it would be problem if message will start with þ. For example I remove rstr2utf8 conversion and provided message þaaa. Now it’s wrong interpreted by explorer as HEX:

http://bob.nem.ninja:8765/#/transfer/d0d80a73c2ac5e055f1f4f10c08302e85575c817487c95827db787f6d4a7863a

because payload starts with ‘fe’

http://192.3.61.243:7890/transaction/get?hash=d0d80a73c2ac5e055f1f4f10c08302e85575c817487c95827db787f6d4a7863a

#9

One more time thanks @CryptoBeliever. Probably the last question here, is payload for the message always in lowercase hex? Can I see something like “FE616161”?

#10

@nem_curious by API it will be returned always lowercase.

#11

Very nice explanation

(not sure if nano allows this right now, but you should also be able to combine hex input with encryption)

1 Like
#12

@gimre you have one-option choice {unencrypted, encrypted, hexadecimal} in nanowallet. So currently it doesn’t allow you to send encrypted hexadecimal message.