Re: #1436 - Fix infinite loop on EOF, eval injection risk, and subshell inefficiency

Starting with: 4. Opaque nested loop in easyrsa_mktemp()

1. I dispute the claim of: Opaque

These two lines of code are self explanatory:
https://github.com/OpenVPN/easy-rsa/blob/0d746eec3f06210ae1710d17b9c8d38428058e19/easyrsa3/easyrsa#L978-L981

They are directly connected by line number. Not Opaque.

(Side note: Hexadecimal could also be used here but we're keeping it simple)

2. I reject changing easysa_mktemp(), from using a string literal (as intended), to using an evaluated numeric string (intentionally avoided), in order to generate a simple string as a file name.

Re: #1436

Prior to the for method above, easyrsa would call openssl, for a random text string, for every new tmp-file, there-by draining the system entropy pool. That was replaced with a predictable, high efficiency string literal, used to name tmp-files. It only looks like mathematics, if you're still trapped in The Matrix.

for high in a s; do
	for low in q w e r t y u i o; do
		shotfile="${secured_session}/temp.${high}${low}"

Start with the nested loops in easyrsa3/easyrsa around lines 978–981 and review the relationship to easyrsa_mktemp(), using issue #1436 for context. The issue does not establish an agreed change or completion criteria, so clarify the intended resolution before modifying code.