Understanding Bitcoin SIGHASH Types and Their Applications
Bitcoin, a decentralized cryptocurrency, relies on various cryptographic techniques to ensure secure and transparent transactions. A crucial aspect of these transactions is the use of Sign Hash (SIGHASH) types, which are used to verify input scripts in the context of Bitcoin.
In this article, we will explore the world of SIGHASH types, their importance in the Bitcoin transaction validation process, and provide guidance on how to determine which type to append to the end of a truncated transaction when verifying the input script.
Types of SGHASH
Bitcoin transactions are divided into two categories: signed and unsigned. Signed transactions contain scripts signed using signature hash (SIGHASH) types, while unsigned transactions do not include script signatures.
The main SIGHASH types used in Bitcoin transactions are:
- SUGHASH zero: This type indicates that the transaction is unsigned.
- SIGHASH one: This type enables input script verification, allowing the miner to validate the contents of the transaction.
- SIGHASH three: Similar to SIGHASH one, but with a larger block size limit.
Verifying cut transactions and input scripts
When verifying input scripts, the hashed transaction goes through several steps before being validated by the miner:
- Verification: The cut transaction is checked for errors or invalid data.
- Input script verification: If the cut transaction has input scripts, they are verified using SIGHASH types.
To determine what type of SIGHASH to append to the end of a truncated transaction during verification, we need to consider the following factors:
- Transaction Signature: The presence and content of the transaction signature (also known as a “SIGHASH zero” signature) will indicate whether input scripts are enabled.
- Input Scripts: If input scripts are present in the transaction, they will be verified using a SIGHASH. To verify input scripts, a miner must have the corresponding private key for each script.
- Block Size Limit: The maximum block size limit imposed by the network (currently 2 MB) will determine what type of SIGHASH is allowed.
Example: Understanding the Sample Transaction
Let’s say we’re looking at a sample transaction:
{
"version": 2,
"txid": "abcdef123",
"voter": [1, 2],
"locktime": 100000,
"confirmations": 10
}
In this case:
- The “version” field (2) indicates an unsigned transaction.
- The
txid,vout, andlocktimefields are present, meaning that input scripts are enabled.
- The “confirmations” field (10) also confirms that the transaction is valid.
To determine what type of SIGHASH to append to the end of this truncated transaction during verification:
- Verify that the transaction signature is a “zero SIGHASH” signature (i.e., it is unsigned). In this case, we assume that the transaction is indeed unsigned.
- Verify the presence and contents of input scripts by examining the “vout” field.
From our analysis, since the transaction has input scripts (the “vout” field), we must append a SIGHASH to enable verification of the input scripts during verification.
Conclusion
In conclusion, determining what type of SIGHASH to append to the end of a truncated transaction when verifying the Bitcoin input script involves considering a variety of factors, including the presence and contents of the transaction signature, verification of the input script, and block size limits. By understanding these concepts, you will be able to ensure that secure and transparent transactions are executed on the Bitcoin network.
Be sure to check out the official documentation for more detailed information on SIGHASH types, transaction verification processes, and other relevant Bitcoin topics.
