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@ -1,5 +1,5 @@ |
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<pre> |
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BIP: 122 |
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BIP: (no number) |
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Title: Transaction Version 2 Specification (wildcard inputs) |
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Author: Chris Priest <cp368202@ohiou.edu> |
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Status: Draft |
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@ -15,7 +15,7 @@ version 1 transactions. |
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==Motivation== |
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Version 1 Bitcoin Transactions have one large inefficiency: When you want to spend |
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from multiple inputs with the exact same scriptSig, you have to list each |
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from multiple inputs with the exact same scriptPubKey, you have to list each |
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input separately, along with the same signature multiple times. |
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This bloats the transaction size and makes it expensive to spend from small value inputs. |
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@ -23,13 +23,32 @@ Because small value inputs are expensive to send, they remain in the UTXO pool |
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which full nodes have to keep around. It is believed that long term increase of the UTXO |
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set can have negative scaling consequences on the network. |
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If maximum blocksize is made to increase *slower* than the actual number of transactins bitcoin users are sending |
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to the network, this problem is projected to get worse. |
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If maximum blocksize is made to increase *slower* than the actual number of transactions bitcoin users are sending |
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to the network, this problem is projected to get worse. In other words, as transaction |
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fees increase, the minimum economical value of a spending a UTXO will increase. |
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==Specification== |
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A version 2 transaction is formulated the exact same way as a version 1 transaction |
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with one exception: each input is treated as a "wildcard input". |
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A wildcard input beings the value of all inputs with the exact same scriptSig |
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A wildcard input beings the value of all inputs with the exact same scriptPubKey |
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in a block lower or equal to the block the wildcard input is confirmed into. |
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== Changes needed to implement == |
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The bitcoin code needs to be modified in three places in order to handle Version 2 Transactions. |
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1. **Full Node V2 validation** - When a full node receives a V2 transaction, it has to |
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aggregate the value of all the UTXOs in the blockchain older than the input |
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with the same scriptPubKey. If this value is greater than or equal to the |
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amount of all outputs, then that V2 transaction is valid and can be propagated. |
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2. **Full Node V1 validation** - When a V1 transaction comes in, the code needs to be modified |
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to check if each inut has not been spent by a V2 transaction. If there exist any |
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V2 transaction in the blockchain with the same scriptPubKey *after* that input, |
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then the UTXO has been spent and the transaction is invalid. |
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3. **Wallet** - The user facing wallet portion of the reference client should notify |
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the user when their wallet contains many UTXOs that qualify it to benefit from |
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a V2 transaction. Wallets should not simply replace V1 transactions with V2 transactions. |
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