Refactor code structure

Move X.509 and Openpgp operations into custom packages. Implement more
robust input reading. Do not convert []byte to string unnecessarily.

Finish implementation of X.509 CRL creation.

shared/io.go

@@ -1,6 +1,7 @@
 package shared
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"time"
@@ -13,31 +14,36 @@ func ReceiveBytes(port io.Reader, count int, timeout time.Duration) ([]byte, err
 	readCh := make(chan []byte, 1)
 	errCh := make(chan error, 1)
 	go func() {
-		sumRead := 0
-		for {
-			data := make([]byte, count)
+		buffer := bytes.NewBuffer([]byte{})
+		for remainder := count; remainder > 0; {
+			data := make([]byte, remainder)
 			if readBytes, err := port.Read(data); err != nil {
 				errCh <- err
+				return
 			} else if readBytes > 0 {
-				log.Tracef("%d bytes read", readBytes)
-				sumRead += readBytes
-				readCh <- data[0:readBytes]
-			} else {
-				readCh <- make([]byte, 0)
-			}
-			if sumRead >= count {
-				break
+				buffer.Write(data[0:readBytes])
+				remainder -= readBytes
+				log.Tracef("%d bytes read, remaining %d", readBytes, remainder)
 			}
 		}
+		readCh <- buffer.Bytes()
+		close(readCh)
 	}()
+
+	buffer := bytes.NewBuffer([]byte{})
 	select {
 	case <-time.After(timeout):
 		return nil, fmt.Errorf("timeout passed %v", timeout)
 	case err := <-errCh:
 		return nil, err
 	case data := <-readCh:
-		return data, nil
+		log.Tracef("received %d bytes from channel", len(data))
+		if data == nil {
+			break
+		}
+		buffer.Write(data)
 	}
+	return buffer.Bytes(), nil
 }
 
 func SendBytes(port io.Writer, data []byte) error {