UCL library “Not Really Vanished” LZ77 variant 2D. Bit-tagged literal/match stream with an exponential-Golomb offset (with single-symbol repeat-offset shortcut) and a two-tier length code, used inside the UPX executable packer.
| Property | Value |
|---|---|
| Category | Compression Algorithms |
| Sub-category | Dictionary-based |
| Security status | Not classified |
| Complexity | Advanced |
| Inventor | Markus F.X.J. Oberhumer |
| Year | 1999 |
| Origin | Not specified |
| Source | algorithms/compression/nrv2d.js |
Status: not classified — treat as unverified.
No vulnerabilities are recorded for this implementation.
3 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.
Vector 1 — Empty input
| Field | Value |
|---|---|
input |
(empty) |
expected |
00000000 |
Vector 2 — Highly repetitive input (64 ‘A’ bytes)
| Field | Value |
|---|---|
input |
41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 41414141414141414141414141414141 |
expected |
40000000000042b54101 |
Vector 3 — Text sample
| Field | Value |
|---|---|
input |
74686520717569636b2062726f776e20 666f78206a756d7073206f7665722074 6865206c617a7920646f672e20746865 20717569636b2062726f776e20666f78 2e |
expected |
41000000feffffff7468652071756963 6b2062726f776e20666f78206a756d70 73206f76657220185af6ff3c6c617a79 20646f672e1b592e |