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Fortuna

Fortuna is a cryptographically secure PRNG designed by Niels Ferguson and Bruce Schneier. Uses 32 SHA-256 entropy pools with exponential pool scheduling and AES-256 counter mode for output generation.

Properties

Property	Value
Category	Random Number Generators
Sub-category	Cryptographic PRNG
Security status	🛡️ Secure
Complexity	Advanced
Inventor	Niels Ferguson, Bruce Schneier
Year	2003
Origin	🇺🇸 United States
Source	algorithms/random/fortuna.js

Parameters

Parameter	Supported values
Seed sizes	0 bytes (0 bits) to 1024 bytes (8192 bits)

Capabilities

Flag	Value
IsDeterministic	Yes
IsCryptographicallySecure	Yes

Security

Status: 🛡️ Secure

No vulnerabilities are recorded for this implementation.

Documentation

• Practical Cryptography - Ferguson and Schneier (2003)
• LibTomCrypt Implementation
• Fortuna Design Analysis

References

• Wikipedia: Fortuna PRNG
• LibTomCrypt Documentation

Test vectors

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

Vector 1 — Deterministic test - 64 bytes entropy pattern, generate 32 bytes

Field	Value
seed	0123456789abcdef0123456789abcdef 0123456789abcdef0123456789abcdef 0123456789abcdef0123456789abcdef 0123456789abcdef0123456789abcdef
outputSize	32
input	null
expected	224a0fa0d0a71441a7190c4b9fdb0d8660905d0f5f390906ca61d2c469f4b886

Vector 2 — Multiple block test - 128 bytes sequential entropy, generate 64 bytes

Field	Value
seed	000102030405060708090a0b0c0d0e0f 101112131415161718191a1b1c1d1e1f 202122232425262728292a2b2c2d2e2f 303132333435363738393a3b3c3d3e3f 404142434445464748494a4b4c4d4e4f 505152535455565758595a5b5c5d5e5f 606162636465666768696a6b6c6d6e6f 707172737475767778797a7b7c7d7e7f
outputSize	64
input	null
expected	667dbf72dbf3a8b403512fc0e26ec57f 8b3ea2a5bd5efd0cf33b76dcfcf5bdd0 f181a1459a23164744c27c2655b296dd abf72282dd08fd7c01375758cacca9ba

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