CIP-0055? | Babbage Era Protocol Parameters

CIP-0055/README.md

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+---
+CIP: 55
+Title: Babbage Era Protocol Parameters
+Authors: Jared Corduan <jared.corduan@iohk.io>
+Status: Proposed
+Type: Informational
+Created: 2022-05-19
+License: CC-BY-4.0
+Requires: CIP-0028
+---
+
+## Simple Summary/Abstract
+
+This CIP extends CIP-0028 to introduce a change to one of the Alonzo protocol parameters in the Babbage era, namely `lovelacePerUTxOWord`.
+We propose to have this updateable parameter be based on bytes instead of words (eight bytes).
+Additionally, two Alonzo era protocol parameters were removed, namely the decentralization parameter and the extra entropy parameter.
+
+## Motivation
+
+### Lovelace Per UTxO Byte
+
+Since the Shelley era, there has been an minimum number of lovelace requirement for every unspent transaction output.
+This requirement acts like a deposit, guarding the network from dust (the proliferation of small-valued unspent transaction outputs).
+Initially it was a constant value, since the Shelley era UTxO were simple and quite uniform.
+Starting in the Mary era, however, the constant value was replace with a
+[formula](https://cardano-ledger.readthedocs.io/en/latest/explanations/min-utxo-mary.html)
+to account for the variability in outputs that contained multi-assets.
+The formula was [changed again](https://cardano-ledger.readthedocs.io/en/latest/explanations/min-utxo-alonzo.html)
+in the Alonzo era.
+Both the Mary and the Alonzo era formulas provide an upper bound on the size in memory of an unspent transaction output in the Haskell implementation.
+We would like to simplify the formula to instead count the number of bytes in the CBOR serialization.
+
+### Transitional Praos
+
+Two Alonzo era protocol parameters need to be removed for the Babbage era, since they relate to `TPraos`.
+Transitional Praos (named `TPraos` in the code base) is the addition of two features to
+[Praos](https://iohk.io/en/research/library/papers/ouroboros-praosan-adaptively-securesemi-synchronous-proof-of-stake-protocol/),
+which were added to provide a smooth transition from
+[Ouroboros-BFT](https://iohk.io/en/research/library/papers/ouroboros-bfta-simple-byzantine-fault-tolerant-consensus-protocol).
+In particular, Transitional Praos included an overlay schedule which could be tuned by the `d` parameter
+(`d == 1` means that all the blocks are produced by the BFT nodes, `d == 0` means that none of them are).
+It also included a way of injecting extra entropy into the epoch nonce.
+The extra entropy feature was used precisely once, and was
+[explained wonderfully](https://iohk.io/en/blog/posts/2021/03/29/the-secure-transition-to-decentralization)
+by one of the original authors of the Praos paper.
+
+The Babbage era removes both of the "transitional" features of TPraos, rendering the decentralization parameter
+and the extra entropy parameter useless.
+
+
+## Specification
+
+The removal of the decentralization parameter and the extra entropy parameter is self explanatory.
+We now describe the specifacion of the `coinsPerUTxOByte` parameter.
+
+
+### Rename
+
+The name of the protocol parameter is actually `coinsPerUTxOWord` in the Haskell implementation.
+It should be renamed to `coinsPerUTxOByte`.
+
+### Translation from the Alonzo era to the Babbage era
+
+At the moment that the hard fork combinator translates the Alonzo era ledger state to the Babbage era,
+the current value of `coinsPerUTxOWord` will be converted to
+
+```
+⌊ coinsPerUTxOWord / 8 ⌋
+```
+
+### The new minimum lovelace calculation
+
+In the Babbage era, unspent transaction outputs will be required to contain _at least_
+
+```
+|serialized_output| * coinsPerUTxOByte
+```
+
+many lovelace.
+
+## Rationale
+
+We would like the formula for the minimum lovelace in a unspent transaction output
+be simpler and easier to reason about by all users of the Cardano network, while at
+the same time accounting for the size of the output.
+
+## Backwards compatibility
+
+The [translation](#translation-from-the-alonzo-era-to-the-babbage-era) section
+explains how we will transition from the `coinsPerUTxOWord` parameter to the `coinsPerUTxOByte` parameter.
+Starting in the Babbage era, update proposals that want to modify `coinsPerUTxOByte` must bear in mind
+that the measurement is in bytes, not words.
+
+The two protocol parameters that have been removed, `d` and `extraEntropy`, can no longer be used
+in protocol parameter updates.
+
+## Path to Active
+
+As of the time of this writing, this CIP has been implemented, but not release, in the Cardano ledger.
+
+## Copyright
+
+This CIP is licensed under Apache-2.0