Online Double SHA256 Hash Generator
Double SHA-256 (also known as SHA256d or hash256) applies SHA-256 twice: SHA256(SHA256(data)). This is the hash function used in Bitcoin for block headers and transaction IDs.
Bitcoin Usage: Double SHA-256 is used in Bitcoin for mining (proof-of-work), block headers, and transaction identifiers (TXIDs).
What is Double SHA-256?
Double SHA-256 is SHA-256 applied twice in succession: hash = SHA256(SHA256(data)). It is also known as SHA256d or hash256.
Why Double Hashing?
- Length Extension Attack Protection: Prevents certain cryptographic attacks
- Additional Security Margin: Provides extra protection against potential weaknesses
- Bitcoin Standard: Required for Bitcoin protocol compatibility
Bitcoin Applications
- Block Headers: Mining proof-of-work calculation
- Transaction IDs: TXID calculation
- Merkle Trees: Transaction tree hashing
- Address Generation: Part of the address derivation process