Implement initial GPG decryption

src/offline/gpg.go

@@ -0,0 +1,20 @@
+package offline
+
+import (
+	"os/exec"
+	"strings"
+)
+
+// TODO GPG support is a temporary feature - it will be replaced with a different encryption scheme in the future
+// TODO These functions may continue to exist after that point, but consider them deprecated
+
+// DecryptGPG decrypts a GPG-encrypted file and returns the contents as a slice of (trimmed) strings
+func DecryptGPG(targetLocation string) []string {
+	cmd := exec.Command("gpg", "--pinentry-mode", "loopback", "-q", "-d", targetLocation)
+	output, _ := cmd.CombinedOutput()
+	outputSlice := strings.Split(string(output), "\n")
+	for i, lineData := range outputSlice {
+		outputSlice[i] = strings.TrimRight(lineData, " \t") // remove trailing whitespace
+	}
+	return outputSlice
+}