SHA-1 & MD5 Hash Calculator
Compute legacy SHA-1 and MD5 hashes for backward compatibility checks, file integrity verification, and legacy system audits.
Security Notice: SHA-1 & MD5 Are Cryptographically Broken
Practical collision attacks exist for both MD5 (Wang et al., 2004) and SHA-1 (SHAttered, 2017). Never use them for digital signatures, SSL certificates, or password storage. This tool is provided strictly for legacy file integrity verification and checksum lookups.
Why Are SHA-1 & MD5 Considered Insecure?
The History of Collision Attacks (MD5 & SHAttered)
A hash function is considered broken when two distinct inputs can be found that yield the exact same output hash (a collision).
In 2004, Xiaoyun Wang demonstrated practical collisions in MD5 in mere seconds on commodity hardware. In 2017, researchers from CWI Amsterdam and Google published the SHAttered attack, generating two distinct PDF documents with identical SHA-1 hashes. Because of this, NIST formally decommissioned SHA-1 for digital signatures in 2011, and major browsers stopped trusting SHA-1 certificates in 2017.
When Is SHA-1 Still Acceptable and How to Migrate?
SHA-1 is still used in Git object hashing (though Git is actively transitioning to SHA-256 via the Object Format v2 extension) and for legacy deduplication where intentional adversarial collision is not a threat model.
For any security-sensitive application — password hashing, API authentication, HMAC tokens, or TLS certificate chains — migrate immediately to SHA-256 (or SHA-512) for integrity and Argon2id or bcrypt for password storage.