PPL 031 / 177 permanent IDsPrize Problem Ledger · PPLChecked 2026.07.27
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Prize Problem Ledgerdistributed.netPPL 031distributed.net RC5-72 key recovery

Permanent problem IDPPL 031

Verified openInstitutionalcomputational target

Cryptography

distributed.net RC5-72 key recovery

Recover the unknown 72-bit key and plaintext for distributed.net’s published RC5-32/12/9 ciphertext, ordinarily by contributing verified key-space work to the live distributed search.

RC5key searchdistributed computing
01

The problem

Recover the unknown 72-bit key and plaintext for distributed.net’s published RC5-32/12/9 ciphertext, ordinarily by contributing verified key-space work to the live distributed search.

Open since2002project launch
Last checked2026.07.27Catalog verification
02

Reward offers

Offer 01$4,000 allocationDistributed Computing Technologies, Inc.
Documented

The operative replacement pledge allocates $1,000 to the finder, $1,000 to the finder’s team—or the finder if unaffiliated—and $2,000 to the Free Software Foundation. The first verified key ends the project.

Only $2,000 of the base allocation can reach the finder/team; the remainder is a designated donation.

Award source ↗Rules ↗
03

Sources & reading

2 unique reference linksCurrent project page · in progress Claim or award rules
04

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