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XTEA

Extended TEA cipher by Wheeler and Needham with improved key schedule and better security than TEA. Uses 64 rounds with 64-bit blocks and 128-bit keys. Educational cipher for understanding Feistel networks.

Properties

Property	Value
Category	Block Ciphers
Sub-category	Block Cipher
Security status	🎓 Educational Only
Complexity	Beginner
Inventor	David Wheeler, Roger Needham
Year	1997
Origin	🇬🇧 United Kingdom
Source	algorithms/block/xtea.js

Parameters

Parameter	Supported values
Key sizes	16 bytes (128 bits)
Block sizes	8 bytes (64 bits)

Security

Status: 🎓 Educational Only

Known vulnerabilities

Issue	Description	Mitigation
Limited analysis	Less cryptanalysis compared to modern ciphers, potential unknown weaknesses exist	Use modern standardized ciphers like AES for production applications
Related-key attacks	While improved over TEA, XTEA may still be vulnerable to certain related-key attacks	Avoid key reuse and use proper key management practices

Documentation

• TEA extensions and corrections
• Cambridge Computer Laboratory
• Block TEA improvements

References

• Crypto++ XTEA Implementation
• Bouncy Castle XTEA Implementation
• Python XTEA Implementation

Test vectors

2 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.

Vector 1 — XTEA All Zeros Test Vector

Field	Value
key	00000000000000000000000000000000
input	0000000000000000
expected	dee9d4d8f7131ed9

Vector 2 — XTEA Pattern Test Vector

Field	Value
key	0123456789abcdef0123456789abcdef
input	0123456789abcdef
expected	27e795e076b2b537

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