Why did Git migrate from SHA-1 to SHA-256?
SHA-1 produces 160-bit hashes with a known collision weakness. After 30+ years, collision attacks became practical, posing a theoretical integrity risk for very large repositories. SHA-256 provides 256-bit output with no known practical collisions, offering decades of safety. Git's migration is gradual to avoid breaking existing workflows.
Answered in
Merkle Trees: How Git Detects Changes in MillisecondsGit hashes files into nested cryptographic trees to skip unchanged directories in one comparison, finding changes across millions of files faster than scanning.
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