Measured: Full DES-56 Exhaustive Key Search Costs ~$1.2M on Commodity AWS, and Bounded Subspace Attacks Cost $0.41
DES has been considered broken since 1998, but this paper (arXiv 2607.23443) supplies the missing concrete number using today's commodity cloud. A distributed C/OpenMP system across 37 c6i.2xlarge EC2 instances measured 2.91M keys/s per instance (~108M keys/s aggregate) over 15 trials covering keyspace offsets from 10^6 to 1.5x10^10. For small offsets, total time is dominated by ~90s AWS boot latency, giving a mean of 116.8±20.1s at $0.41 per attack; a key at offset 1.5x10^10 takes ~87 minutes and $18. Exhausting the full 2^56 space on those 37 instances would take ~21 years, but because the workload is embarrassingly parallel the authors extrapolate ~$1.2M and about one day with a sufficiently large fleet — firmly within reach of a well-funded attacker renting standard capacity.
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