diff --git a/rfc/0017_transaction_comment_encryption.md b/rfc/0017_transaction_comment_encryption.md
index d57d9d91794c504ff8024d9d89c9ed5e703dad77..39d4041dff27884a417d634d45ab2bca420cb924 100644
--- a/rfc/0017_transaction_comment_encryption.md
+++ b/rfc/0017_transaction_comment_encryption.md
@@ -32,24 +32,24 @@ Encrypt bit per bit with XOR cipher.
 
 ## Serialize encrypted message with meta data
 
-| Prefix  | Message type | Message length | Nonce    | Encrypted message | Padding                    |
-|:-------:|:------------:|:--------------:|:--------:|:-----------------:|:--------------------------:|
-| 2 bytes | 1 byte       | 1 byte         | 12 bytes | Any bytes         | `Message length % 4` bytes |
+| Prefix | Message type | Message length | Nonce    | Encrypted message | Padding                          |
+|:------:|:------------:|:--------------:|:--------:|:-----------------:|:--------------------------------:|
+| 1 byte | 1 byte       | 1 byte         | 12 bytes | Any bytes         | `(1 - Message length) % 4` bytes |
 
 The padding is used so that the quantity of bytes to be serialized is always a multiple of 4. This is necessary for the encoding in base z85.
 
 ### Prefix
 
-A constant value that indicates the type of format. For the present format defined in this RFC, the prefix is `0x0100`. A possible future new format should choose a different prefix. This prefix can also be incremented for a future version of the present format.
+A constant value that indicates the type of format. For the present format defined in this RFC, the prefix is _1_ in [unsigned-varint] format, i.e. `0x01`. A possible future new format should choose a different prefix. This prefix can also be incremented for a future version of the present format. Due to [unsigned-varint], the prefix may be longer in future versions.
 
 ### Message type
 
-| Code | Significance                     |
-|:----:|:--------------------------------:|
-| 0x00 | Write by a human for a human     |
-| 0x01 | Write by a human for a machine   |
-| 0x10 | Write by a machine for a human   |
-| 0x11 | Write by a machine for a machine |
+| Code | Significance                      |
+|:----:|:---------------------------------:|
+| 0x00 | Written by a human to a human     |
+| 0x01 | Written by a human to a machine   |
+| 0x02 | Written by a machine to a human   |
+| 0x03 | Written by a machine to a machine |
 
 ## Encodinq in transaction document
 
@@ -59,4 +59,5 @@ DUBP protocol accept all [base z85] characters except `$`. We replace `$` by `_`
 
 [base z85]: https://rfc.zeromq.org/spec/32/
 [crypto_box_beforenm]: https://nacl.cr.yp.to/box.html
+[unsigned-varint]: https://github.com/multiformats/unsigned-varint
 [XOR cipher]: https://en.wikipedia.org/wiki/XOR_cipher