参考

https://csrc.nist.gov/pubs/sp/800/57/pt1/r2/final
https://www.linuxquestions.org/questions/linux-security-4/1024-bit-dsa-vs-2048-bit-rsa-4175439131/
https://csrc.nist.gov/CSRC/media/Projects/Key-Management/documents/transitions/Transitioning_CryptoAlgos_070209.pdf
https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-57p1r2007.pdf

推荐限制

If information is initially signed in 2009 and needs to remain secure for a maximum of ten years (i.e., from 2009 to 2019), a 1024 bit RSA key would not provide sufficient protection between 2011 and 2019 and, therefore, it is not recommended that 1024-bit RSA be used in this case. It is recommended that the algorithms and ke