A. SHA-1 (Secure Hash Algorithm 1)
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Developed by: NSA and published by NIST in 1995.
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Digest Size: 160 bits (20 bytes).
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Input Size: Arbitrary length (processed in 512-bit blocks).
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Output: 160-bit fixed hash value.
Process:
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The message is divided into 512-bit blocks.
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Each block goes through multiple rounds of processing involving logical functions, bitwise operations, and modular additions.
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Final output is a 160-bit digest.
Security Status:
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Broken: In 2017, a practical collision attack was demonstrated by Google and CWI Amsterdam.
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No longer considered secure for cryptographic purposes.
B. SHA-512 (Part of SHA-2 Family)
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Developed by: NSA and published by NIST in 2001.
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Digest Size: 512 bits (64 bytes).
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Input Size: Arbitrary length (processed in 1024-bit blocks).
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Output: 512-bit fixed hash value.
Process:
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Uses 64-bit words and processes input in 1024-bit chunks.
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Involves 80 rounds of mixing operations using logical functions, constants, and modular additions.
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Designed to resist known cryptographic attacks.
Security Status:
- Secure: As of today, SHA-512 remains secure and is widely recommended for high-security applications.
Conclusion
A secure hash function ensures data integrity, authenticity, and confidentiality. While SHA-1 is no longer suitable for secure systems due to vulnerability to collision attacks, SHA-512 offers a high level of security and is widely adopted in modern cryptographic protocols.