Hawkynt

Self-Shrinking Generator

Self-Shrinking Generator (SSG) is a pseudorandom generator derived from a single Linear Feedback Shift Register (LFSR). It processes LFSR output in pairs: the first bit is a selector, and the second bit is output only when the selector is 1. Introduced as a structurally simpler alternative to the two-LFSR Shrinking Generator, it is a well-studied cryptographic building block but is not considered secure against modern cryptanalysis and should not be used for cryptographic purposes.

Properties

Property Value
Category Random Number Generators
Sub-category Cryptographic PRNG
Security status 🎓 Educational Only
Complexity Intermediate
Inventor Willi Meier and Othmar Staffelbach
Year 1994
Origin 🇨🇭 Switzerland
Source algorithms/random/self-shrinking-generator.js

Parameters

Parameter Supported values
Seed sizes 1 byte (8 bits) to 8 bytes (64 bits)

Capabilities

Flag Value
IsDeterministic Yes
IsCryptographicallySecure No

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

References

Test vectors

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

Vector 1 — SSG Test Vector 1: Polynomial 0x3B, Seed 0x01

Field Value
seed 01
polynomial 59
outputSize 8
input null
expected 20240a0007702aa0

Vector 2 — SSG Test Vector 2: Polynomial 0x3B, Seed 0xFF

Field Value
seed ff
polynomial 59
outputSize 8
input null
expected f9ffed42be2f7f92

Vector 3 — SSG Test Vector 3: Polynomial 0xD5, Seed 0x42

Field Value
seed 42
polynomial 213
outputSize 8
input null
expected 40cc111100c88844

Vector 4 — SSG Test Vector 4: Polynomial 0x3B, Seed 0xAB

Field Value
seed ab
polynomial 59
outputSize 8
input null
expected baa4b49aaa802aae

Vector 5 — SSG Test Vector 5: Polynomial 0x3B, Seed 0x12

Field Value
seed 12
polynomial 59
outputSize 8
input null
expected 0694062519a00000

← All algorithms

This site is open source. Improve this page.