trezor-firmware/core/src/apps/cardano

Cardano

MAINTAINER = Rafael Korbaš rafael.korbas@vacuumlabs.com

ORIGINAL AUTHOR = Juraj Muravský juraj.muravsky@vacuumlabs.com

REVIEWER = Jan Matejek jan.matejek@satoshilabs.com, Tomas Susanka tomas.susanka@satoshilabs.com

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Useful links

Cardano documentation - official documentation. Cardano developer documentation - official developer documentation. Delegation Design Spec - contains information about delegation (addresses, certificates, withdrawals, ...). Multi Asset CDDL spec. Byron address format. The Shelley 1852' purpose and staking path. cbor.me - very useful tool for CBOR inspection.

Important notes

Unfortunately we are aware of the fact that currently at most ~14 inputs are supported per transaction. To resolve this, the cardano app will have to be rewritten to support transaction streaming.

Cardano requires a custom seed.py file and Keychain class. This is because the original Cardano derivation schemes don't separate seed generation from key tree derivation and also because we need to support both Byron (44') and Shelley (1852') purposes. More on this can be found here and here.

Cardano uses extended public keys. This also means that the transaction signature is built using the ed25519.sign_ext function.

Protocol magic vs. Network id

Protocol magic is used to identify the network on the protocol level. Each network (mainnet, testnet, testnet 2, ...) has its own protocol magic. It's a 4 byte number. Network Id is a more compact version of the protocol magic - it's only 4 bits. It is used in addresses to determine, whether they belong to a testnet or any of the (possibly in the future existing) mainnets. Network Id 0 is reserved for all the testnets that might ever exist and the remaining 15 values are used for mainnets. Current mainnet protocol magic: 764824073 Current mainnet network id: 1

Key types

In Shelley two types of keys are used. Payment key and staking key. Payment keys are derived from m/1852'/1815'/x/[0,1]/y paths and are used for holding/transfering funds. Staking keys are derived from m/1852'/1815'/x/2/0 paths, thus there is only one staking key per account. They are used for staking operations - certificates, withdrawals. Shelley addresses are built from the combination of hashes of these keys.

Addresses

Since the Shelley era Cardano supports multiple address types. Information about address types added in Shelley can be found here. In short, all Shelley address types contain a header, which is 1 byte long. The header is built as: ((address_type << 4) | networkId). Byron address has an address type of 0b1000 but never contains the network id. Instead, protocol magic is included in the address in a different way (more about that here).

Address encoding (Base58 vs. Bech32)

In Shelley, address encoding has been switched from Base58 to Bech32. However, Byron addresses still need to be encoded as Base58. Other address types use Bech32. Thus both formats need to be supported.

Byron address

Legacy address used mainly during the Byron era, but still supported in Shelley. Has no staking rights. More about address format can be found here. Example: Mainnet: Ae2tdPwUPEZCanmBz5g2GEwFqKTKpNJcGYPKfDxoNeKZ8bRHr8366kseiK2 Testnet: 2657WMsDfac7BteXkJq5Jzdog4h47fPbkwUM49isuWbYAr2cFRHa3rURP236h9PBe

Base address

Introduced in Shelley: [header] + [payment_key_hash] + [staking_key_hash] Base address can have staking rights (as it contains a staking key hash), but the staking key has to be registered on the blockchain first. Funds can be received even without the staking key being registered though. It is also possible to own the funds (payment key) but to use a different staking key to build the address. This would transfer the staking rights to the owner of the staking key. This can be useful for staking your funds for a charity. Example: Mainnet: addr1q8v42wjda8r6mpfj40d36znlgfdcqp7jtj03ah8skh6u8wnrqua2vw243tmjfjt0h5wsru6appuz8c0pfd75ur7myyeqsx9990 Testnet: addr_test1qrv42wjda8r6mpfj40d36znlgfdcqp7jtj03ah8skh6u8wnrqua2vw243tmjfjt0h5wsru6appuz8c0pfd75ur7myyeqnsc9fs

Pointer address

Introduced in Shelley: [header] + [payment_key_hash] + [certificate_pointer] Certificate pointer is a pointer (block, transaction, certificate) to the staking key registration certificate on the blockchain. It replaces staking_key_hash from base address, but serves the same purpose. Thus pointer address is pretty much the same as base address in function, but is much shorter (~35B vs 57B) thanks to the certificate pointer. Example: Mainnet: addr1gxq0nckg3ekgzuqg7w5p9mvgnd9ym28qh5grlph8xd2z92spqgpsl97q83 Testnet: addr_test1gzq0nckg3ekgzuqg7w5p9mvgnd9ym28qh5grlph8xd2z925ph3wczvf2ag2x9t

Enterprise address

Introduced in Shelley: [header] + [payment_key_hash] Entreprise address has no staking rights. This is useful for example for exchanges which contain a lot of funds and thus would control too much stake. Example: Mainnet: addr1vxq0nckg3ekgzuqg7w5p9mvgnd9ym28qh5grlph8xd2z92su77c6m Testnet: addr_test1vzq0nckg3ekgzuqg7w5p9mvgnd9ym28qh5grlph8xd2z92s8k2y47

Reward address

Introduced in Shelley: [header] + [staking_key_hash] Staking rewards are gathered on this address after stake registration and delegation. They can then be withdrawn by a transaction with withdrawals filled in. All of the rewards have to be taken out at once. Example: Mainnet: stake1uyfz49rtntfa9h0s98f6s28sg69weemgjhc4e8hm66d5yacalmqha Testnet: stake_test1uqfz49rtntfa9h0s98f6s28sg69weemgjhc4e8hm66d5yac643znq

Transactions

Transactions don't have a distinct type. Every transaction may transfer funds, post a certificate, withdraw funds or do all at once (to a point).

Unfortunately we are aware of the fact that currently at most ~14 inputs are supported per transaction. This should be resolved when the cardano app is updated to support transaction streaming.

Witnesses

Transactions need a witness (signature) for each input, withdrawal and some certificates. A witness for each key is included only once in a transaction. The signature is built using the ed25519.sign_ext function. There are significant differences between Byron and Shelley witnesses - although we need to support both, because a transaction may have Byron inputs.

Shelley witnesses: They only need to contain the public key (not the extended public key) and the signature. Nothing else is needed to verify the signature, although the signing happens with an extended private key.

Byron witnesses: In order to be able to properly verify them, Byron witnesses need to contain the public key, signature, chain code and address attributes (which are empty on mainnet or contain the protocol magic on testnet).

More on witness structure can be found here.

Multi Asset support

Multi Asset support has been added in the Cardano Mary era

Quote from developer docs:

This feature extends the existing accounting infrastructure defined in the ledger model, which is designed for processing ada-only transactions, to accommodate transactions that simultaneously use a range of assets. These assets include ada and a variety of user-define custom token types.

Transaction outputs may include custom tokens on top of ADA tokens:

1: [
 [
  address, [
   ADA_amount, {
    policy_id: {
     asset_name: asset_amount
    }}]]]

Please see the transaction below for more details.

The serialized transaction output size is currently limited to 512 bytes. This limitation is a mitigation measure to prevent sending large (especially change) outputs containing many tokens that Trezor would not be able to spend given that currently the full Cardano transaction is held in-memory. Once Cardano-transaction signing is refactored to be streamed, this limit can be lifted

Certificates

Certificates are posted to the blockchain via transactions and they mark a certain action, thus there are multiple certificate types:

• stake key registration certificate
• stake key de-registration certificate
• delegation certificate

And these three which are not supported by Trezor at the moment:

• stake pool registration certificate
• stake pool retirement certificate
• operational key certificate

Stake key de-registration and delegation certificates both need to be witnessed by the corresponding staking key.

You can read more on certificates in the delegation design spec. Info about their structure can be found here.

Withdrawals

Withdrawals are posted to the blockchain via transactions and they are used to withdraw rewards from reward accounts. When withdrawing funds, the transaction needs to be witnessed by the corresponding staking key.

You can read more on withdrawals in the delegation design spec (there is not a dedicated section to withdrawals, simply search for 'withdrawal').

Metadata

Each transaction may contain metadata. Metadata format can be found here. It's basically a CBOR serialized map and can contain numbers, bytes, strings or nested maps/lists.

Due to memory limitations we currently enforce a maximum size of 500 bytes for metadata.

Transaction Explorer

Cardano explorer.

Submitting a transaction

You can use a combination of cardano-node and cardano-cli (part of the cardano-node repo) to submit a transaction.

Serialization format

Cardano uses CBOR as a serialization format. Here is the CDDL specification for after Multi Asset support has been added.

Raw transaction example

83a700818258203b40265111d8bb3c3c608d95b3a0bf83461ace32d79336579a1939b3aad1c0b700018282583901eb0baa5e570cffbe2934db29df0b6a3d7c0430ee65d4c3a7ab2fefb91bc428e4720702ebd5dab4fb175324c192dc9bb76cc5da956e3c8dff821904d2a1581c95a292ffee938be03e9bae5657982a74e9014eb4960108c9e23a5b39a14874652474436f696e1910e18258390180f9e2c88e6c817008f3a812ed889b4a4da8e0bd103f86e7335422aa122a946b9ad3d2ddf029d3a828f0468aece76895f15c9efbd69b427719115c02182a030a048182008200581c122a946b9ad3d2ddf029d3a828f0468aece76895f15c9efbd69b427705a1581de1122a946b9ad3d2ddf029d3a828f0468aece76895f15c9efbd69b42771903e80814a10082825820bc65be1b0b9d7531778a1317c2aa6de936963c3f9ac7d5ee9e9eda25e0c97c5e5840c6e85c7eec254f765ddc119b1f40ef50944dcb1882822c3d61641785bbc312d1049ed0a92ded74745986f5d464d0d0caafc9f0c66285a056309d3d39cf19b20e8258205d010cf16fdeff40955633d6c565f3844a288a24967cf6b76acbeb271b4f13c158401feabb9e56bca7d3cb75f0942d1ebaec92f167193c70fb9b416e9ae3d3e0f368f49fde3f4a862eb6a02f9a27834d0b7c1f6dd689616809432c99f3ab7249ad0ef6

The same transactions with structure description

# transaction
# array(3)
[
 # transaction body
 # map(6)
 {
   # inputs [id, index]
   # uint(0), array(1), array(2), bytes(32), uint(0)
   0: [[h'3B4...', 0]],

   # outputs [address, [ada_amount, { policy_id => { asset_name => asset_amount }}]]
   # uint(1), array(2)
   1: [
    # multi asset output
    # array(2), bytes(57), uint(1234), map(1), bytes(28), map(1), bytes(8), uint(4321)
    [
     h'01E...', [
      1234, {
       h'95A...': {
        h'74652474436F696E': 4321
       }
      }
     ]
    ],
    # output containing only ADA [address, ada_amount]
    # array(2), bytes(57), uint(4444)
    [h'018...', 4444],
   ]

   # fee
   # uint(2), uint(42)
   2: 42,

   # ttl
   # uint(3), uint(10)
   3: 10,

   # certificates [[type, [keyhash/scripthash, keyhash]]]
   # uint(4), array(1), array(2), uint(0), array(2), uint(0), bytes(28)
   4: [[0,[0, h'122...']]],

   # withdrawal [reward_address: amount]
   # uint(5), map(1), bytes(29), uint(7204944340)
   5: {h'E11...': 1000},

   # validity_interval_start
   # uint(8), uint(20)
   8: 20
 },
  # witnesses
  # map(1)
 {
   # verifying key witnesses [[vkey -> signature]]
   # uint(0), array(2)
   0: [
       # array(2), bytes(32), bytes(64)
       [h'BC6...', h'C6E...'],
       # array(2), bytes(32), bytes(64)
       [h'5D0...', h'1FE...']
   ]
 },

 # metadata
 # primitive(22)
 null
]