Which statement about SHA-1 is commonly accepted?

• A. They are deprecated due to weaknesses
• B. They are the most secure hash functions
• C. They produce quantum-safe results
• D. They are encryption algorithms

Answer: (A)

SHA-1 has known weaknesses that led to its deprecation. It’s a 160-bit hash function that was once trusted for integrity and digital signatures, but researchers have demonstrated practical collisions—two different inputs producing the same hash—undermining its collision resistance. Because attackers can exploit these collisions in signatures or certificates, security standards and major platforms now require migrating away from SHA-1 to stronger options like SHA-256 or SHA-3. It’s not an encryption algorithm, and the issue is not about quantum safety; it’s about vulnerable collision resistance. That combination of weaknesses and real-world exploitability is why its deprecation is widely accepted.