Researchers reproduce RC2 key-schedule π table generation method
What happened
A Hacker News front-page post on October 19 reports that researchers reproduced the 256-byte PITABLE in RC2's key schedule exactly, plus another table of unknown origin in RFC 2268. They used the decimal digits of π as the random source and a Fisher–Yates shuffle. Each draw read a fixed three digits, biased draws were discarded, and the whole shuffle used 828 digits. Rivest's MD2 uses the same shuffle but reads a different number of digits per draw, which the post suggests may be a previously unnoticed reason. The result does not affect RC2's security.
Written by AI from the coverage · updated 2 hours ago
Coverage
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- Hacker News front pageHow RC2's π table was made
研究者用 Fisher–Yates 洗牌、以 π 的十进制数字作为随机源，精确复现了 RC2 密钥调度中 256 字节的 PITABLE 及 RFC 2268 中另一张来源未明的表。每次抽取固定读取三位数字，偏差抽取被丢弃，整个洗牌共使用 828 位数字。该方法与 Rivest 的 MD2 使用同一洗牌但每次读取位数不同，这可能是此前未被发现的原因；结果不影响 RC2 的安全性。
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