pith:OKQ6B4BA
Cryptanalysis of the Legendre Pseudorandom Function over Extension Fields
The single-degree Legendre PRF over extension fields admits efficient key recovery through periodic fracture bucketing and geometric-sequence collisions.
arxiv:2604.04833 v3 · 2026-04-06 · cs.CR · math.NT
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\usepackage{pith}
\pithnumber{OKQ6B4BATZFOUK5AQTSLKR6HS3}
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Record completeness
Claims
We demonstrate that an adversary can systematically group fractured sequences by their structural shapes to bypass this defense, recovering the secret key in O(U · p^r/M) operations... an adversary can circumvent the additive fracture by evaluating the PRF along a geometric sequence generated by a primitive polynomial... extract the key in O(p^r/M) operations. Finally, we establish the cryptographic boundaries of these attacks, formally proving the necessity of higher-degree key variants (d ≥ 2) to achieve exponential security against structural reduction in extension fields.
The analysis relies on polynomial input encoding without carry-overs producing a deterministically periodic fracture, and on the existence of primitive polynomials enabling strict multiplicative homomorphism in the active model; if real implementations use different encodings or the fracture periodicity does not hold as claimed, the bucketing and collision attacks may fail.
The Legendre PRF over extension fields admits key recovery in O(p^r/M) operations via differential signature bucketing on fractured sequences or geometric sequence queries exploiting multiplicative homomorphism, proving higher-degree keys are required for exponential security.
Receipt and verification
| First computed | 2026-05-25T02:01:18.931731Z |
|---|---|
| Builder | pith-number-builder-2026-05-17-v1 |
| Signature | Pith Ed25519
(pith-v1-2026-05) · public key |
| Schema | pith-number/v1.0 |
Canonical hash
72a1e0f0209e4aea2ba084e4b547c796d68f2a643322ebfbe09eff4d857cc050
Aliases
· · · · ·Agent API
Verify this Pith Number yourself
curl -sH 'Accept: application/ld+json' https://pith.science/pith/OKQ6B4BATZFOUK5AQTSLKR6HS3 \
| jq -c '.canonical_record' \
| python3 -c "import sys,json,hashlib; b=json.dumps(json.loads(sys.stdin.read()), sort_keys=True, separators=(',',':'), ensure_ascii=False).encode(); print(hashlib.sha256(b).hexdigest())"
# expect: 72a1e0f0209e4aea2ba084e4b547c796d68f2a643322ebfbe09eff4d857cc050
Canonical record JSON
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"license": "http://creativecommons.org/licenses/by/4.0/",
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"submitted_at": "2026-04-06T16:35:32Z",
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