<p>Some of the checksums in Bitcoin are the first 4 bytes of the HASH256 of the data. HASH256 is just double SHA256, so <code>SHA256(SHA256(data))</code>. What is the advantage of that over using a dedicated checksum function, like CRC32?</p>

CC BY-SA 4.0
2024-03-08T15:09:48.507Z
Hi dbv, in case it is relevant, you seem to be asking about a specific application of checksums, but there are many different places in which checksums appear. Not all of them use the construction you describe, for example checksums in Bech32 and Bech32m addresses use BCH codes.
Murch
CC BY-SA 4.0
2024-03-11T20:15:02.433Z
Hi Murch, thanks for clarification. I updated the question.
dbv
<address><hash><sha256><checksum>
What is the advantage of using truncated HASH256 over CRC32?
dbv
# What is the advantage of using truncated HASH256 over CRC32?

(Asked by: username_0 on 2024-03-04)

Some of the checksums in Bitcoin are the first 4 bytes of the HASH256 of the data. HASH256 is just double SHA256, so `SHA256(SHA256(data))`. What is the advantage of that over using a dedicated checksum function, like CRC32?

**Tags:** address, hash, sha256, checksum

> **Comments:**
> **username_1**: Hi dbv, in case it is relevant, you seem to be asking about a specific application of checksums, but there are many different places in which checksums appear. Not all of them use the construction you describe, for example checksums in Bech32 and Bech32m addresses use BCH codes.  
> **username_0**: Hi username_1, thanks for clarification. I updated the question.  

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