feat(cmd): conversion of PEM-encoded ED25519 node keys

[lklimek]

Issue being fixed or feature implemented

For various key management processes it is useful to be able to use existing ED25519 keys as Tenderdash node keys.
Various tools, like OpenSSL, generate keys in PEM format.
PEM keys need to be converted in order to use in Tenderdash, which uses its own (JSON) key storage format.

What was done?

tenderdash gen-node-key was extended by adding additional flag, --from-pem:

      --from-pem-file string          read PEM-encoded ED25519 private key file (use '-' for stdin)

How Has This Been Tested?

Using OpenSSL, generated ED25519 private key:

openssl genpkey -algorithm ed25519 -out privkey.pem

Generated node ID for this private key:

openssl pkey -in privkey.pem -noout  -text_pub |tail -n +3 | tr -d '[:space:]' | xxd -r -p| sha256sum | head -c 40
ec95355821c3b172455d8ca75898b0d15e9a2de2

Used provided privkey.pem to generate Tenderdash keys, and compare node ID with the one in id field:

go run ./cmd/tenderdash gen-node-key  --from-pem-file /tmp/privkey.pem 
{"id":"ec95355821c3b172455d8ca75898b0d15e9a2de2","priv_key":{"type":"tendermint/PrivKeyEd25519","value":"sku7KdJcQXvzrwTd6ZaCuHB4H2hzZ4ZS0/P7hntW+i42dXcOr+umuF+huhiWG8XxSGEUU+MCFEtUp1iynm/EIw=="}}

Breaking Changes

None

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone

[shotonoff]

please, have a look at the questions/comments/suggestions

[shotonoff]

LGTM

[shotonoff]

🚀