Take the 2-minute tour ×  Is it possible to have multiple key
lengths in a PKI? For example, use a 1024-bit key for the issued
certificate, a 2048-bit key for the intermediate certificate,
and 4096-bit key for the root certificate? I don't know a lot
about PKI, but does this make sense?  share|improve this
question add comment  1 Answer  Yes, each certificate stands on
its own, and can be any bit length without any connection to the
length of certificates which it signs or which have signed it.
And yes, it may make more sense to have a root certificate,
which is used rarely but requires more security, be a longer key
length than a web server certificate, which is used often and
where the computational speed has an impact.  share|improve this
answer Exactly, and different cert types under a CA can have
different lengths - say a high-use, low risk app gets a small
key, and a low-use, high risk app needs a bigger key - most CAs
let you set up multiple profiles, and the user picks the type of
cert they need. – 