C# Get CngKey object from public key in text file

Question

I have got a file in which there are several public keys for ECDSA SHA256. The file looks like:

KEY_ID: 1
STATUS: VALID
-----BEGIN PUBLIC KEY-----
MFkwEwYHKo         


        

Answer 1

I've been parsing files like this for 40 years. Code like this has long history

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;


namespace ConsoleApplication62
{
    enum State
    {
        FIND_KEY,
        GET_STATUS,
        GET_KEY_STRINGS
    }
    class Program
    {
        const string FILENAME = @"c:\temp\test.txt";
        static void Main(string[] args)
        {
            new Key(FILENAME);

        }

    }
    public class Key
    {
        public static List keys = new List();

        public int id { get; set; }
        public Boolean status { get; set; }
        List keysStrs = new List();

        public Key() { }
        public Key(string filename)
        {
            StreamReader reader = new StreamReader(filename);
            string inputLine = "";

            State state = State.FIND_KEY;
            Key newKey = null;
            while((inputLine = reader.ReadLine()) != null)
            {
                inputLine = inputLine.Trim();
                if(inputLine.Length > 0)
                {
                    switch (state)
                    {
                        case State.FIND_KEY :
                            if(inputLine.StartsWith("KEY_ID:"))
                            {
                                newKey = new Key();
                                keys.Add(newKey);
                                int id = int.Parse(inputLine.Substring(inputLine.LastIndexOf(" ")));
                                newKey.id = id;
                                state = State.GET_STATUS;
                            }
                            break;

                        case State.GET_STATUS:
                            if (inputLine.StartsWith("STATUS:"))
                            {
                                string status = inputLine.Substring(inputLine.LastIndexOf(" ")).Trim();
                                newKey.status = status == "VALID" ? true : false;
                                state = State.GET_KEY_STRINGS;
                            }                            
                            break;

                        case State.GET_KEY_STRINGS:
                            if (!inputLine.StartsWith("-"))
                            {
                                newKey.keysStrs.Add(inputLine.Trim());
                            }
                            else
                            {
                                if (inputLine.Contains("END PUBLIC KEY"))
                                {
                                    state = State.FIND_KEY;
                                }
                            }
                            break;
                    }
                }

            }
        }
    }
}