Git 3.0's upcoming SHA-256 default will be a costly mistake

Git 3.0 will change its default hash algorithm from SHA-1 to SHA-256, a move prompted by published SHA-1 collision attacks that show the 160-bit hash is no longer cryptographically secure. The new algorithm offers stronger collision resistance but may introduce significant compatibility and performance costs. The change reflects the need to mitigate theoretically possible malicious hash collisions.