[tiffanyh]

Is it a coincidence the generated keys start with the same first 3 letters (“MII…”)?

[kstrauser]

Nope. See https://www.thedigitalcatonline.com/blog/2018/04/25/rsa-keys... for example:

"Please note that, due to the structure of the underlying ASN.1 structure, RSA PEM bodies start always with the same characters: MIG for 1024 bit keys, MII for 2048 and 4096 bit ones."

[tiffanyh]

Seems like this would be susceptible to an Inference Attack.

[kstrauser]

Hmm, I wouldn’t think so, but I’m not an expert in such things. If you already have access to that text, you’ve won. I wouldn’t think that would leak any extra information.