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Diffstat (limited to 'bip-0158.mediawiki')
| -rw-r--r-- | bip-0158.mediawiki | 33 |
1 files changed, 15 insertions, 18 deletions
diff --git a/bip-0158.mediawiki b/bip-0158.mediawiki index 5ebfaed..054aa1f 100644 --- a/bip-0158.mediawiki +++ b/bip-0158.mediawiki @@ -19,7 +19,7 @@ This BIP describes a structure for compact filters on block data, for use in the BIP 157 light client protocol<ref>bip-0157.mediawiki</ref>. The filter construction proposed is an alternative to Bloom filters, as used in BIP 37, that minimizes filter size by using Golomb-Rice coding for compression. This -document specifies two initial types of filters based on this construction that +document specifies one initial filter type based on this construction that enables basic wallets and applications with more advanced smart contracts. == Motivation == @@ -27,9 +27,8 @@ enables basic wallets and applications with more advanced smart contracts. [[bip-0157.mediawiki|BIP 157]] defines a light client protocol based on deterministic filters of block content. The filters are designed to minimize the expected bandwidth consumed by light clients, downloading filters -and full blocks. This document defines two initial filter types, ''basic'' and -''extended'', to provide support for advanced applications while reducing the -filter size for regular wallets. +and full blocks. This document defines the initial filter type ''basic'' +that is designed to reduce the filter size for regular wallets. == Definitions == @@ -274,18 +273,16 @@ This BIP defines one initial filter type: The basic filter is designed to contain everything that a light client needs to sync a regular Bitcoin wallet. A basic filter MUST contain exactly the following items for each transaction in a block: -* The previous output script (the script being spent) for each input, except - for the coinbase transaction. -* The scriptPubKey of each output, aside from all <code>OP_RETURN</code> output - scripts. +* The previous output script (the script being spent) for each input, except for the coinbase transaction. +* The scriptPubKey of each output, aside from all <code>OP_RETURN</code> output scripts. Any "nil" items MUST NOT be included into the final set of filter elements. -We exclude all <code>OP_RETURN</code> outputs in order to allow filters to -easily be committed to in the future via a soft-fork. A likely area for future -commitments is an additional <code>OP_RETURN</code> output in the coinbase -transaction similar to the current witness commitment -<ref>https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki</rev>. By +We exclude all outputs that start with <code>OP_RETURN</code> in order to allow +filters to easily be committed to in the future via a soft-fork. A likely area +for future commitments is an additional <code>OP_RETURN</code> output in the +coinbase transaction similar to the current witness commitment +<ref>https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki</ref>. By excluding all <code>OP_RETURN</code> outputs we avoid a circular dependency between the commitment, and the item being committed to. @@ -300,9 +297,9 @@ one is able to select <code>P</code> and <code>M</code> independently, then setting <code>M=1.497137 * 2^P</code> is close to optimal <ref>https://gist.github.com/sipa/576d5f09c3b86c3b1b75598d799fc845</ref>. -Empirical analysis also shows that was chosen as these parameters minimize the -bandwidth utilized, considering both the expected number of blocks downloaded -due to false positives and the size of the filters themselves. +Empirical analysis also shows that these parameters minimize the bandwidth +utilized, considering both the expected number of blocks downloaded due to false +positives and the size of the filters themselves. The parameter <code>k</code> MUST be set to the first 16 bytes of the hash (in standard little-endian representation) of the block for which the filter is @@ -325,7 +322,7 @@ This BIP allocates a new service bit: |- | NODE_COMPACT_FILTERS | style="white-space: nowrap;" | <code>1 << 6</code> -| If enabled, the node MUST respond to all BIP 157 messages for filter types <code>0x00</code> and <code>0x01</code> +| If enabled, the node MUST respond to all BIP 157 messages for filter type <code>0x00</code> |} == Compatibility == @@ -350,7 +347,7 @@ Light client: [https://github.com/lightninglabs/neutrino] Full-node indexing: https://github.com/Roasbeef/btcd/tree/segwit-cbf -Golomb-Rice Coded sets: https://github.com/Roasbeef/btcutil/tree/gcs/gcs +Golomb-Rice Coded sets: https://github.com/btcsuite/btcutil/blob/master/gcs == Appendix A: Alternatives == |