Unexpected serialization of PoolRegistration cert

[AngelCastilloB]

The pool registration certificate is defined in the CDDL as:

pool_registration = (3, pool_params)

I would expect this to be serialized to something like: [ 03, [ pool param data ] ] (array of 2 elements with a nested array of 9 elements for pool params), or in CBOR:

82                                      # array(2)
   03                                   # unsigned(3)
   89                                   # array(9)
      58 1C                             # bytes(28)
         D85087C646951407198C27B1B950FD2E99F28586C000CE39F6E6EF92 # "\xD8P\x87\xC6F\x95\u0014\a\u0019\x8C'\xB1\xB9P\xFD.\x99\xF2\x85\x86\xC0\u0000\xCE9\xF6\xE6\xEF\x92"
      58 20                             # bytes(32)
         8DD154228946BD12967C12BEDB1CB6038B78F8B84A1760B1A788FA72A4AF3DB0 # "\x8D\xD1T\"\x89F\xBD\u0012\x96|\u0012\xBE\xDB\u001C\xB6\u0003\x8Bx\xF8\xB8J\u0017`\xB1\xA7\x88\xFAr\xA4\xAF=\xB0"
      19 2710                           # unsigned(10000)
      19 03E8                           # unsigned(1000)
      D8 1E                             # tag(30)
         82                             # array(2)
            01                          # unsigned(1)
            05                          # unsigned(5)
      58 1D                             # bytes(29)
         E1CB0EC2692497B458E46812C8A5BFA2931D1A2D965A99893828EC810F # "\xE1\xCB\u000E\xC2i$\x97\xB4X\xE4h\u0012ȥ\xBF\xA2\x93\u001D\u001A-\x96Z\x99\x898(\xEC\x81\u000F"
      81                                # array(1)
         58 1C                          # bytes(28)
            CB0EC2692497B458E46812C8A5BFA2931D1A2D965A99893828EC810F # "\xCB\u000E\xC2i$\x97\xB4X\xE4h\u0012ȥ\xBF\xA2\x93\u001D\u001A-\x96Z\x99\x898(\xEC\x81\u000F"
      83                                # array(3)
         83                             # array(3)
            01                          # unsigned(1)
            19 1388                     # unsigned(5000)
            6B                          # text(11)
               6578616D706C652E636F6D   # "example.com"
         84                             # array(4)
            00                          # unsigned(0)
            19 1770                     # unsigned(6000)
            44                          # bytes(4)
               7F000001                 # "\u0000\u0000\u0001"
            F6                          # primitive(22)
         82                             # array(2)
            02                          # unsigned(2)
            6B                          # text(11)
               6578616D706C652E636F6D   # "example.com"
      82                                # array(2)
         73                             # text(19)
            68747470733A2F2F6578616D706C652E636F6D # "https://example.com"
         58 20                          # bytes(32)
            0F3ABBC8FC19C2E61BAB6059BF8A466E6E754833A08A62A6C56FE0E78F19D9D5 # "\u000F:\xBB\xC8\xFC\u0019\xC2\xE6\e\xAB`Y\xBF\x8AFnnuH3\xA0\x8Ab\xA6\xC5o\xE0\xE7\x8F\u0019\xD9\xD5"

However the CML is serializing this certificate as [ 03 + pool param data] (single flat array of 10 elements), or in CBOR:

8A                                      # array(10)
   03                                   # unsigned(3)
   58 1C                                # bytes(28)
      D85087C646951407198C27B1B950FD2E99F28586C000CE39F6E6EF92 # "\xD8P\x87\xC6F\x95\u0014\a\u0019\x8C'\xB1\xB9P\xFD.\x99\xF2\x85\x86\xC0\u0000\xCE9\xF6\xE6\xEF\x92"
   58 20                                # bytes(32)
      8DD154228946BD12967C12BEDB1CB6038B78F8B84A1760B1A788FA72A4AF3DB0 # "\x8D\xD1T\"\x89F\xBD\u0012\x96|\u0012\xBE\xDB\u001C\xB6\u0003\x8Bx\xF8\xB8J\u0017`\xB1\xA7\x88\xFAr\xA4\xAF=\xB0"
   19 2710                              # unsigned(10000)
   19 03E8                              # unsigned(1000)
   D8 1E                                # tag(30)
      82                                # array(2)
         01                             # unsigned(1)
         05                             # unsigned(5)
   58 1D                                # bytes(29)
      E1CB0EC2692497B458E46812C8A5BFA2931D1A2D965A99893828EC810F # "\xE1\xCB\u000E\xC2i$\x97\xB4X\xE4h\u0012ȥ\xBF\xA2\x93\u001D\u001A-\x96Z\x99\x898(\xEC\x81\u000F"
   81                                   # array(1)
      58 1C                             # bytes(28)
         CB0EC2692497B458E46812C8A5BFA2931D1A2D965A99893828EC810F # "\xCB\u000E\xC2i$\x97\xB4X\xE4h\u0012ȥ\xBF\xA2\x93\u001D\u001A-\x96Z\x99\x898(\xEC\x81\u000F"
   83                                   # array(3)
      83                                # array(3)
         01                             # unsigned(1)
         19 1388                        # unsigned(5000)
         6B                             # text(11)
            6578616D706C652E636F6D      # "example.com"
      84                                # array(4)
         00                             # unsigned(0)
         19 1770                        # unsigned(6000)
         44                             # bytes(4)
            7F000001                    # "\u0000\u0000\u0001"
         F6                             # primitive(22)
      82                                # array(2)
         02                             # unsigned(2)
         6B                             # text(11)
            6578616D706C652E636F6D      # "example.com"
   82                                   # array(2)
      73                                # text(19)
         68747470733A2F2F6578616D706C652E636F6D # "https://example.com"
      58 20                             # bytes(32)
         0F3ABBC8FC19C2E61BAB6059BF8A466E6E754833A08A62A6C56FE0E78F19D9D5 # "\u000F:\xBB\xC8\xFC\u0019\xC2\xE6\e\xAB`Y\xBF\x8AFnnuH3\xA0\x8Ab\xA6\xC5o\xE0\xE7\x8F\u0019\xD9\xD5"

This is different that how the other structures are serialized, in which each sub structure is encoded as is as a single entry in the parent array, is there any reason why this particular case is different?

[rooooooooob]

@AngelCastilloB notice how pool_params is defined:

pool_params = ( operator:       pool_keyhash
              , vrf_keyhash:    vrf_keyhash
              , pledge:         coin
              , cost:           coin
              , margin:         unit_interval
              , reward_account: reward_account
              , pool_owners:    set<addr_keyhash>
              , relays:         [* relay]
              , pool_metadata:  pool_metadata / null
              )

pool_params is a basic group (it is NOT encoded as an array - notice the ( and ) not [ and ]) which means the fields will be inserted into pool_registration.

[AngelCastilloB]

Hi @rooooooooob I see now, thanks for the information and the quick reply!.

[rooooooooob]

If you want more info about basic groups and the behavior check out section 2.1 of the CDDL RFC (groups and composition). Keep in mind in babbage.cddl (and ONLY in babbage - previous eras seem to correctly follow the basic group insertion for operational certs/versions) we seem to have the babbage.cddl spec possibly incorrect regarding basic groups (input-output-hk/cardano-ledger#3559). The currently published CML hasn't been updated regarding this but the next version should have that fix (#246). It's only an issue if you're working with babbage blocks/block headers though.

[AngelCastilloB]

This is really useful @rooooooooob thanks