起因於 Infineon Technologies 在產生 key 時的組合有限，於是要猜測的 keyspace 小很多。
以研究者的估算，可以看出 CPU year 都被大幅減少了，都是屬於「可行」的範圍：
The time complexity and cost for the selected key lengths (Intel E5-2650 v3@3GHz Q2/2014):
512 bit RSA keys - 2 CPU hours (the cost of $0.06);
1024 bit RSA keys – 97 CPU days (the cost of $40-$80);
2048 bit RSA keys – 140.8 CPU years, (the cost of $20,000 - $40,000).
而且這邊是用 CPU year 估算，如果考慮 FPGA 加速計算，應該會短更多...
2nd of November 2017 - Presentation of all details at the ACM CCS conference (to come)
16th of October 2017 - The initial version of the public disclosure published
May to October 2017 - Cooperation with the manufacturer and other affected parties to help evaluate and mitigate the vulnerability
1st of February - The vulnerability disclosed to Infineon Technologies AG
End of January - The vulnerability found
過一陣子就會去 conference 上報告了...