Hawkynt

Base91

Base91 (basE91) encoding using 91-character alphabet for efficient binary-to-text encoding. Achieves only 23% overhead compared to Base64’s 33% by using variable-length bit packing. Developed by Joachim Henke for maximum efficiency.

Properties

Property	Value
Category	Encoding Schemes
Sub-category	Base Encoding
Security status	🎓 Educational Only
Complexity	Advanced
Inventor	Joachim Henke
Year	2000
Origin	🇩🇪 Germany
Source	`algorithms/encoding/base91.js`

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

References

Test vectors

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

Vector 1 — Base91 empty string test

Field	Value
`input`	(empty)
`expected`	(empty)

Vector 2 — Base91 single character test - ‘a’

Field	Value
`input`	`61`
`expected`	`4742`

Vector 3 — Base91 word test - ‘test’

Field	Value
`input`	`74657374`
`expected`	`66504e4b64`

Vector 4 — Base91 palindrome test with newline

Field	Value
`input`	`4e65766572206f6464206f72206576656e0a`
`expected`	`5f4f5e6770404a6037527a746a626c4c41235f31654841`

Vector 5 — Base91 sentence test with newline

Field	Value
`input`	`4d61792061206d6f6f6479206261627920646f6f6d20612079616d3f0a`
`expected`	`3844394b63293d2f3224577a65467569 2347394b6d2b3c7b56543275394d5a69 6c7d5b41`

Vector 6 — Base91 all 256 byte values regression test - exercises the 91st alphabet symbol (double quote)

Field Value

input 000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f 404142434445464748494a4b4c4d4e4f 505152535455565758595a5b5c5d5e5f 606162636465666768696a6b6c6d6e6f 707172737475767778797a7b7c7d7e7f 808182838485868788898a8b8c8d8e8f 909192939495969798999a9b9c9d9e9f a0a1a2a3a4a5a6a7a8a9aaabacadaeaf b0b1b2b3b4b5b6b7b8b9babbbcbdbebf c0c1c2c3c4c5c6c7c8c9cacbcccdcecf d0d1d2d3d4d5d6d7d8d9dadbdcdddedf e0e1e2e3e4e5e6e7e8e9eaebecedeeef f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff

expected 3a4323283a433f685642244d53695645 776e6442414d5a527877466642423b49 573c7d59515621415f7624595f63257a 723463595150466c302c4068654d414a … (315 bytes; the full value is in the source)

Field	Value
`input`	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f 404142434445464748494a4b4c4d4e4f 505152535455565758595a5b5c5d5e5f 606162636465666768696a6b6c6d6e6f 707172737475767778797a7b7c7d7e7f 808182838485868788898a8b8c8d8e8f 909192939495969798999a9b9c9d9e9f a0a1a2a3a4a5a6a7a8a9aaabacadaeaf b0b1b2b3b4b5b6b7b8b9babbbcbdbebf c0c1c2c3c4c5c6c7c8c9cacbcccdcecf d0d1d2d3d4d5d6d7d8d9dadbdcdddedf e0e1e2e3e4e5e6e7e8e9eaebecedeeef f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff
`expected`	`3a4323283a433f685642244d53695645 776e6442414d5a527877466642423b49 573c7d59515621415f7624595f63257a 723463595150466c302c4068654d414a …` (315 bytes; the full value is in the source)

Vector 7 — Base91 pseudo-random 128-byte regression test - exercises the decode bit-queue-length branch for a decode value above the 13-bit mask (8191)

Field	Value
`input`	`614d13f8a060bea6b2892cc12663c843 464cbfe81f5efd2e7d762e4fec2fbd48 b7e7d8d5ebb86871547f1c5a7dd75f8a b41e5cbd036e007136a4f6e0db5bac07 3cf14ca26680c32c25e5bde205bba5c0 5160a88216eeb2a420426f61faf74ab6 f26a705f12b8cdd726ba0d5bbc0f9be7 1e11a43759de14c7394f97d24a039955`
`expected`	`366c234252585b406364364e544e354e 32587d79363154783346647b64363870 2471617d43727e6f286f2665684b3b6b 7535524c69234d713d515d2f67753126 6d6e7857616d686c7a5f516e667b4a56 6c6b5a3762225d6a2b5a77724b685b3d 5f222e42336438667d675e357e466167 477b243945676c38245e7047326d7e23 5b6f52214c3e466d233d424775263d30 394f423360364e61456c2f316041`

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