# SHA-0

> individual cryptographic hash function with output size of 160 bits

**Wikidata**: [Q3459557](https://www.wikidata.org/wiki/Q3459557)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/SHA-0)  
**Source**: https://4ort.xyz/entity/sha-0

## Summary
SHA-0 is a cryptographic hash function that produces a 160-bit output, originally designed as part of the SHA (Secure Hash Algorithm) family. Released in 1993, it was the first version of the SHA series but was later superseded due to vulnerabilities.

## Key Facts
- SHA-0 is an individual cryptographic hash function with a 160-bit output size.
- It was introduced in 1993 as the initial version of the SHA hash function family.
- Also known by aliases: SHA 0, SHA0, Secure Hash Algorithm 0, SHA, Sha-0.
- Classified under the SHA hash functions family, which includes other cryptographic hash functions.
- Assigned the ITU/ISO/IEC object identifier: 1.3.14.3.2.18.
- Wikipedia entries exist in German (de), English (en), and French (fr).
- Google Knowledge Graph ID: /g/1232phzp.
- Sitelink count: 3 (as of available data).

## FAQs
**What is SHA-0?**
SHA-0 is the original cryptographic hash function in the SHA family, producing a 160-bit output. It was released in 1993 but was later replaced due to security weaknesses.

**What are the aliases for SHA-0?**
SHA-0 is also referred to as SHA 0, SHA0, Secure Hash Algorithm 0, SHA, and Sha-0.

**What is the output size of SHA-0?**
SHA-0 generates a fixed-size output of 160 bits, consistent with early cryptographic hash function standards.

**When was SHA-0 introduced?**
SHA-0 was first published in 1993 as part of the Secure Hash Algorithm series.

**What is the relationship between SHA-0 and the SHA family?**
SHA-0 is the foundational member of the SHA hash functions family, a group of cryptographic hash functions widely used in security applications.

## Why It Matters
SHA-0 laid the groundwork for modern cryptographic hash functions, establishing the 160-bit output standard that influenced later versions like SHA-1. While it was later deemed insecure, its development marked a critical step in the evolution of secure hashing algorithms, shaping digital signatures, data integrity verification, and other cryptographic applications. Its vulnerabilities also provided valuable lessons for improving subsequent hash functions.

## Notable For
- Being the first version of the SHA (Secure Hash Algorithm) family.
- Introducing a 160-bit output size, a standard adopted by later hash functions.
- Serving as a precursor to more secure variants like SHA-1, despite its eventual deprecation.
- Holding an official ITU/ISO/IEC object identifier (1.3.14.3.2.18), indicating its recognition in international standards.

## Body
### **History and Development**
SHA-0 was released in 1993 as the initial iteration of the Secure Hash Algorithm (SHA) series, developed by the U.S. National Security Agency (NSA). It was designed to address the need for a secure hash function in cryptographic applications, particularly for digital signatures and data integrity checks. However, shortly after its release, vulnerabilities were discovered, leading to its replacement by SHA-1.

### **Technical Specifications**
- **Output Size**: 160 bits, a standard that persisted in later SHA variants.
- **Aliases**: Known by multiple names, including SHA 0, SHA0, and Secure Hash Algorithm 0.
- **Standards Compliance**: Assigned the ITU/ISO/IEC object identifier 1.3.14.3.2.18, reflecting its inclusion in international cryptographic standards.

### **Relationship to the SHA Family**
SHA-0 is the foundational member of the SHA hash functions family, a class of cryptographic hash functions that includes SHA-1, SHA-2, and SHA-3. While SHA-0 was quickly superseded, its design principles influenced subsequent versions, particularly in maintaining the 160-bit output structure.

### **Documentation and Recognition**
- **Wikipedia Coverage**: Entries exist in English, German, and French, indicating its historical significance in cryptography.
- **Google Knowledge Graph**: Identified under the ID /g/1232phzp, confirming its recognition in structured knowledge bases.
- **Sitelink Count**: 3, reflecting its presence in multiple online knowledge repositories.

### **Legacy and Impact**
Despite its vulnerabilities, SHA-0 played a pivotal role in the development of secure hashing algorithms. Its flaws highlighted the importance of rigorous cryptanalysis, leading to stronger successors like SHA-1 and SHA-2. The lessons learned from SHA-0’s weaknesses contributed to advancements in cryptographic security, ensuring more robust hash functions for modern applications.