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UUencode

UUencoding (Unix-to-Unix encoding) binary-to-text encoding developed by Mary Ann Horton at UC Berkeley in 1980. Encodes 3 bytes into 4 characters using printable ASCII characters with space (0x20) offset. Widely used in early email and UUCP systems.

Properties

Property	Value
Category	Encoding Schemes
Sub-category	Binary-to-Text
Security status	🎓 Educational Only
Complexity	Beginner
Inventor	Mary Ann Horton
Year	1980
Origin	🇺🇸 United States
Source	algorithms/encoding/uuencode.js

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

• POSIX IEEE Std 1003.1-2017
• UUencoding Wikipedia
• Original UUCP Documentation

References

• Berkeley Unix Manual
• UUencode Online Tool
• RFC 1341 MIME UUencoding

Test vectors

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

Vector 1 — UUencode empty string test

Field	Value
input	(empty)
expected	(empty)

Vector 2 — UUencode single zero byte test

Field	Value
input	00
expected	2020

Vector 3 — UUencode single character ‘M’ test

Field	Value
input	4d
expected	3330

Vector 4 — UUencode two character ‘Ma’ test

Field	Value
input	4d61
expected	333624

Vector 5 — UUencode three character ‘Man’ test

Field	Value
input	4d616e
expected	3336254e

Vector 6 — UUencode four character ‘Test’ test - full 3-byte group (‘Tes’) plus a 1-byte tail group (‘t’) encoded as its full 2 characters

Field	Value
input	54657374
expected	352635533d20

Vector 7 — UUencode 128-byte regression test - final group is a 2-byte tail, not the whole input, so the old data.length-based tail check silently dropped its 3rd character

Field	Value
input	61616161616161616161616161616161 61616161616161616161616161616161 61616161616161616161616161616161 61616161616161616161616161616161 61616161616161616161616161616161 61616161616161616161616161616161 61616161616161616161616161616161 61616161616161616161616161616161
expected	38362541383625413836254138362541 38362541383625413836254138362541 38362541383625413836254138362541 38362541383625413836254138362541 38362541383625413836254138362541 38362541383625413836254138362541 38362541383625413836254138362541 38362541383625413836254138362541 38362541383625413836254138362541 38362541383625413836254138362541 3836254138362541383624

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