[RFC17] change base z85 -> base 64

rfc/0017_transaction_comment_encryption.md

@@ -32,12 +32,11 @@ 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         | `4 - (Message length % 4)` bytes |
+| Prefix  | Message type | Message length | Nonce    | Encrypted message |
+|:-------:|:------------:|:--------------:|:--------:|:-----------------:|
+| 2 bytes | 1 byte       | 1 byte         | 12 bytes | Any bytes         |
 
-The maximum length of a message is 186 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.
+The maximum length of a message is 173 bytes.
 
 ### Prefix
 
@@ -54,10 +53,7 @@ A constant value that indicates the type of format. For the present format defin
 
 ## Encodinq in transaction document
 
-Encrypted message in encoded in [base z85] in transaction comment directly.
+Encrypted message in encoded in base 64 in transaction comment directly (DUBP protocol already accept all base 64 characters).
 
-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
 [XOR cipher]: https://en.wikipedia.org/wiki/XOR_cipher