# SHA-2

> set of cryptographic hash functions designed by the NSA

**Wikidata**: [Q1968605](https://www.wikidata.org/wiki/Q1968605)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/SHA-2)  
**Source**: https://4ort.xyz/entity/sha-2

## Summary
SHA-2 is a set of cryptographic hash functions designed by the National Security Agency (NSA), part of the broader class of cryptographic hash functions. It includes multiple variants such as SHA-224, SHA-256, SHA-384, and SHA-512, each with distinct output sizes and security properties. The standard was established in 2002 and later revised, with SHA-3 succeeding it in 2015.

## Key Facts
- **Designed by**: National Security Agency (NSA)
- **Inception**: 2002
- **Followed by**: SHA-3 (2015)
- **Aliases**: SHA-512/224, SHA512/256, SHA 2, SHA-224, SHA512/224, SHA256, SHA-512/256, SHA-384, SHA-256, SHA224, SHA512, SHA384, Secure Hash Algorithm 2, SHA-512, SHA2, 安全散列演算法2
- **Classifications**: Technical standard, cryptographic hash function
- **Subclass of**: Cryptographic hash function, technical standard
- **Contains**: SHA-512/224, SHA-512/256, SHA-224, SHA-384, SHA-512
- **Described by**: RFC 4634, RFC 6234
- **Wikipedia languages**: Arabic, Catalan, German, English, Spanish, Basque, Persian, French, Hebrew, Hungarian, Indonesian, Italian, Japanese, Korean, Latvian, Polish, Portuguese, Romanian, Russian, Serbian, Turkish, Ukrainian, Uzbek, Wu Chinese, Chinese, Min Nan Chinese
- **GitHub topic**: sha-2
- **Rosetta Code page**: SHA-256
- **File format wiki page**: SHA-2
- **Wikidata description**: Set of cryptographic hash functions designed by the NSA

## FAQs
**What is SHA-2?**
SHA-2 is a set of cryptographic hash functions designed by the NSA, consisting of multiple variants like SHA-224, SHA-256, SHA-384, and SHA-512, each with different output sizes and security properties.

**When was SHA-2 created?**
SHA-2 was established in 2002, with later revisions and updates.

**What are the main variants of SHA-2?**
The main variants include SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256.

**What is the difference between SHA-2 and SHA-3?**
SHA-2 was designed by the NSA and succeeded by SHA-3, which was standardized in 2015.

**Which organizations use SHA-2?**
SHA-2 is part of technical standards and cryptographic hash functions, used in various security protocols and applications.

## Why It Matters
SHA-2 is a foundational cryptographic standard used for secure data integrity and authentication. Its variants provide different levels of security, making it suitable for various applications from digital signatures to password hashing. The standard was revised in 2015 to address potential vulnerabilities, with SHA-3 introduced as a successor. Its widespread adoption ensures secure data transmission and storage across digital systems.

## Notable For
- **Multiple variants**: Includes SHA-224, SHA-256, SHA-384, and SHA-512, each with distinct output sizes.
- **NSA-designed**: Developed by the National Security Agency, reflecting its role in cryptographic standards.
- **Technical standard**: Recognized as a required norm for consistent cryptographic practices.
- **Predecessor to SHA-3**: Succeeded by SHA-3 in 2015, marking a significant update in cryptographic algorithms.

## Body
### History
SHA-2 was designed by the NSA and established in 2002. It includes multiple variants with different output sizes, each tailored for specific security needs. The standard was later revised, with SHA-3 succeeding it in 2015.

### Variants
SHA-2 consists of several variants:
- **SHA-224**: 224-bit output size
- **SHA-256**: 256-bit output size
- **SHA-384**: 384-bit output size
- **SHA-512**: 512-bit output size
- **SHA-512/224**: 224-bit output derived from SHA-512
- **SHA-512/256**: 256-bit output derived from SHA-512

### Technical Standards
SHA-2 is classified as a technical standard, ensuring consistent implementation across cryptographic applications. It is described by RFC 4634 and RFC 6234, providing detailed specifications for its use.

### Related Standards
SHA-2 is part of the broader class of cryptographic hash functions and technical standards. It preceded SHA-3, which was standardized in 2015.

### Wikipedia and Documentation
SHA-2 is documented in multiple languages on Wikipedia, including Arabic, Catalan, German, English, Spanish, and others. It is also referenced in technical documents like RFC 4634 and RFC 6234.

### GitHub and Development
The GitHub topic "sha-2" is associated with SHA-2, indicating its relevance in software development and cryptographic libraries.

### File Formats and Usage
SHA-2 is referenced in file format documentation, highlighting its role in ensuring data integrity and security in digital systems.

## References

1. Freebase Data Dumps. 2013
2. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)