CIP-0020: Transaction messages/comments metadata

CIP-0010/registry.json

@@ -1,4 +1,8 @@
 [
+  {
+    "transaction_metadatum_label": 674,
+    "description": "CIP-0020 - Transaction message/comment metadata"
+  },
   {
     "transaction_metadatum_label": 1967,
     "description": "nut.link metadata oracles registry"

CIP-0020/CIP-0020.md

@@ -0,0 +1,102 @@
+---
+CIP: 20
+Title: Transaction message/comment metadata
+Authors: Martin Lang <[email protected]>, Ola Ahlman <[email protected]>, Andrew Westberg <[email protected]>
+Comments-URI: no comments yet
+Status: Draft
+Type: Informational
+Created: 2021-06-13
+License: CC-BY-4.0
+---
+
+# Abstract
+
+This proposal describes a basic JSON schema to add messages/comments/memos as transaction metadata by using the metadatum label **674**.
+Adding **informational text, invoice-numbers or similar** to a transaction on the cardano blockchain.
+
+# Motivation
+
+We have the utilities on the cardano blockchain now since the introduction of the "allegra-era". A simple consens about adding messages, comments or memos to transactions is still missing.
+So the CIP authors came together to form a first implementation of this. It is straight and simple, additional keys and content can be added later.
+The IOG main wallet `Daedalus` can now also directly show attached metadata information in the transaction details view. This CIP is the missing link to bring it together.
+
+Current Tools/Sites/Explorers that have implemented it already or have plans to implement it:
+* [CNTools](https://cardano-community.github.io/guild-operators/#/Scripts/cntools)
+* [JorManager](https://bitbucket.org/muamw10/jormanager/)
+* [StakePoolOperator Scripts](https://github.com/gitmachtl/scripts)
+* [Cardanoscan.io](https://cardanoscan.io)
+* [AdaStat.net](https://adastat.net)
+* [CardanoCommunityWallet](https://ccwallet.io)
+* [CardanoWall](https://cardanowall.com)
+
+# Specification
+
+The specification for the individual strings follow the general design specification for JSON metadata, which is already implemented and in operation on the cardano blockchain.
+The used metadatum label is **`"674":`**, this number was choosen because it is the T9 encoding of the string "msg".
+The message content has the key **`"msg":`** and consists of an array of individual **message-strings**. 
+The number of theses **message-strings** must be at least one for a single message, more for multiple messages/lines. Each of theses individual **message-strings** array entries must be at most 64 bytes when UTF-8 encoded.
+
+Format:
+``` 
+{ 
+  "674":
+         { "msg": 
+                  [ 
+                    "message-string 1" //Optional: ,"message-string 2","message-string 3" ...
+                  ]
+         }
+}
+```
+
+
+
+Example for a single message/comment/memo:
+``` json
+{ 
+  "674":
+         { "msg": 
+                  [ 
+                    "This is a comment for the transaction xyz, thank you very much!"
+                  ]
+         }
+}
+```
+
+Example for multiple messages/comments/memos:
+``` json
+{ 
+  "674":
+         { "msg": 
+                  [ 
+                    "Invoice-No: 1234567890",
+                    "Customer-No: 555-1234",
+                    "P.S.: i will shop again at your store :-)"
+                  ]
+         }
+}
+```
+Example above in **Daedalus** currently (could be improved if CIP is implemented):
+![image](https://user-images.githubusercontent.com/47434720/121822100-85b38a80-cc9d-11eb-9d13-1869746a69b2.png)
+
+**Cardanoscan.io**, **Adastat.net** and other tools implemented it already, to show messages along transactions:
+![image](https://user-images.githubusercontent.com/47434720/124379245-1f2af680-dcb6-11eb-97b7-10f70d840e88.png)
+![image](https://user-images.githubusercontent.com/47434720/124381343-3ff94900-dcc2-11eb-8d03-8fbacd3322b0.png)
+
+**ccwallet.io** has added it with a message field on the sending-page, and shows it also on the transactions-page:
+![image](https://user-images.githubusercontent.com/47434720/127367420-b360972d-c6e0-4002-865e-df070904bd30.png)
+![image](https://user-images.githubusercontent.com/47434720/127367228-339ac059-007a-40fd-a6c0-97f890e93964.png)
+![image](https://user-images.githubusercontent.com/47434720/127368912-c85dc9f0-6ee3-4cc1-a24b-9716a20f27d3.png)
+
+
+# Rationale
+
+This design is simple, so many tools on the cardano blockchain can implement it easily. The array type was choosen to have consistency, no need to switch between a string or
+an array format, or testing against a string or array format. Updates in the future are possible, like adding a versioning key `"ver":`, adding a key `"utxo":` to provide specific data for every tx-out#idx in the transaction, making subarrays in the message-strings, etc. But for now, we need a common agreement to provide general messages/comments/memos with this CIP. The starting design war choosen as simple as possible to keep the additional transaction fees as low as possible.
+
+## Wallet Implementation
+
+Would be a good idea to hide the message/comment/note behind a "show unmoderated content" button/drop-down. Like the Metadata display on the Cardano Explorer. Also, it should be displayed as plain-text non-clickable. To enhance security further, URLs could be automatically deleted or hidden from such comments, to not welcome bad actors with phishing attempts. Another solution to start with would be to really limit the character space for display in Wallets, like limiting it to `a-zA-z0-9` and a handful of special chars like `+-_#()[]:` without a `.<>"/\` chars, so a domain or html code would not work. Last points are worth for discussions of course, because it would also filter out unicode.
+
+# Copyright
+
+This CIP is licensed under [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/legalcode)