BIP32 amendment: base58chk-encoded extended keys are always 111 chars #1584

1. 
   jonatack commented at 9:56 pm on April 30, 2024: contributor

   Replaces #727. The description below is copied from that PR.

   Base58chk-encoded extended keys are always 111 characters long. Amend wording of BIP32 accordingly.

   Diff: -This results in a Base58-encoded string of up to 112 characters. +This results in a Base58-encoded string of exactly 111 characters.

   Proof: Version bytes: 0x0488b21e (“xpub”), 0x0488ade4 (“xprv”), 0x043587cf (“tpub”), 0x04358394 (“tprv”)

   Largest version byte is 0x0488b21e, smallest 0x04358394.

   Largest “possible” key:

   0kL = 0x0488b21effffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff (78 bytes)
   1b58chk(kL) = xpubEPi3iGSX9RiyuXPTijevUmMctBDQs2TWCMgUd3qKp6qCgUc8RUsPdPBrRC6whFeWTg37DcmnJJiKFL73DH4sjdApJkXBD3vFcBP4xHq3fPY
   2len(b58chk(kL)) = 111
   

   Smallest “possible” key:

   0kS = 0x043583940000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 (78 bytes)
   1b58chk(kS) = tprv8ZgxMBicQKsPcsbCVeqqF1KVdH7gwDJbxbzpCxDUsoXHdb6SnTPYxdwSAKDC6KKJzv7khnNWRAJQsRA8BBQyiSfYnRt6zuu4vZQGKjeW4YF
   2len(b58chk(kS)) = 111
   

2. Base58chk-encoded extended keys are always 111 characters long. Amend wording of BIP accordingly.

   -This results in a Base58-encoded string of up to 112 characters.
   +This results in a Base58-encoded string of exactly 111 characters.
   
   Version bytes: 0x0488b21e (“xpub”), 0x0488ade4 (“xprv”), 0x043587cf (“tpub”), 0x04358394 (“tprv”)
   
   Largest “possible” key:
      kL = 0x0488b21effffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff (78 bytes)
      b58chk(kL) = xpubEPi3iGSX9RiyuXPTijevUmMctBDQs2TWCMgUd3qKp6qCgUc8RUsPdPBrRC6whFeWTg37DcmnJJiKFL73DH4sjdApJkXBD3vFcBP4xHq3fPY (111 chars)
   
   Smallest “possible” key:
      kS = 0x043583940000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 (78 bytes)
      b58chk(kS) = tprv8ZgxMBicQKsPcsbCVeqqF1KVdH7gwDJbxbzpCxDUsoXHdb6SnTPYxdwSAKDC6KKJzv7khnNWRAJQsRA8BBQyiSfYnRt6zuu4vZQGKjeW4YF (111 chars)

   f1c296bb32
3. 
   jonatack commented at 9:58 pm on April 30, 2024: contributor

   Replaces #727 with cherry-picked 81644ddfa131bb0e387ead2cc309ca18e57542b1; note that BIP32 has status Final.

   Pinging @sipa for feedback.

4. jonatack added the label Proposed BIP modification on Apr 30, 2024
5. murchandamus assigned sipa on May 1, 2024
6. murchandamus added the label Pending acceptance on May 8, 2024
7. TyG34 approved
8. TyG34 approved
9. TyG34 approved
10. TyG34 approved

Contributors
jonatack TyG34

Labels
Proposed BIP modification Pending acceptance