What is the source of crypto for encrypted strings

General
1

Where does confd get its crypto algorithms? Do they come from openssl?
i.e. if we have openssl on board in FIPS mode, is it using those algorithms or are they hand rolled or from some other source?

2

And just for clarity, I am specifically asking about yang like this:
type tailf:aes-cfb-128-encrypted-string;

Using the tailf encrypted strings type.

3

ConfD uses the OpenSSL libcrypto shared library for cryptographic functions.