Bitcoin: Understanding v28.0 PayToAnchor script

février 13, 2025

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Understanding the PayToAnchor Script v28.0: A Guide

Bitcoin, the first decentralized cryptocurrency, has undergone significant improvements to its underlying blockchain technology. The latest version of Bitcoin, v28.0, introduces a new script called PayToAnchor (PTA). In this article, we delve into the world of PayToAnchor and explore its inner workings.

What is PayToAnchor?

PayToAnchor is a script that allows anchor nodes to be used as payment addresses for transactions on the Bitcoin blockchain. Anchor nodes are responsible for verifying transaction data, creating new blocks, and maintaining the integrity of the blockchain. By using PTA, these nodes can now act as payment anchors, allowing them to accept payments from other users without having to broadcast the entire transaction.

PayToAnchor Script v28.0

The PayToAnchor script v28.0 is defined in the script.cpp file of the Bitcoin source code repository. Here is a high-level overview of the script:


#include 
#include "script/script.h"
namespace bitcoin {
struct anchor_script {
uint8_t paytoanchor_code[18];
uint8_t paytoanchor_data_size;
AnchorScriptType paytoanchor_type;
};
struct paytoanchor_script {
PayToAnchor paytoanchor;
};
PAYTOANCHOR_SCRIPT(paytoanchor_script)
: paytoanchor(AnchorScriptType::PayToAnchor) {}
} // bitcoin namespace

The variable `paytoanchor'' is an instance of theAnchorScriptType::PayToAnchor'' enumeration, which specifies the type of anchor node represented by the script.


PaytoAnchor Script Data Structure
The paytoanchor_script structure contains two members:

paytoanchor_code'': an 18-byte array containing the pay-to-anchor code used for the transaction data.

paytoanchor_data_size: an unsigned int specifying the size of the data paid to the anchors.

`paytoanchor_type: an enumeration value defining the type of anchor node.

AnchorScriptType

The `AnchorScriptType'' namespace defines two values: PayToAnchor and Unknown Anchor (UAN). The PayToAnchor value indicates that this script represents a pay-to-anchor node, while UAN is used when no specific anchor node type is specified.


PaytoAnchors on the Bitcoin network
When a transaction is broadcast to the Bitcoin network using the PayToAnchor script v28.0, it is split into three parts:

The transaction data itself.


The Pay to Anchors header (PAYTOANCHOR_SCRIPT), which defines the anchor node type and the associated code.


The remaining transaction data.

The pay-to-anchors header is encoded in two 32-byte blocks:paytoanchor_codeandpaytoanchor_data_size`. The first block contains the pay-to-anchors code, while the second block contains the pay-to-anchors data size.

Conclusion

In summary, the v28.0 PayToAnchor script is a key component of Bitcoin’s scalability improvements. By allowing anchor nodes to act as payment addresses, this script facilitates the creation of new blockchains and increases the overall functionality of the Bitcoin network. Understanding the underlying mechanisms of PayToAnchor scripts can help developers working on Bitcoin-related projects develop more efficient solutions to improve scalability and usability.

Additional Resources