diff --git a/src/cmd_directdecrypt.rs b/src/cmd_directdecrypt.rs
index 219dd8b..c7ced37 100644
--- a/src/cmd_directdecrypt.rs
+++ b/src/cmd_directdecrypt.rs
@@ -14,16 +14,16 @@ use crate::util_progress::Progress;
 
 #[derive(Debug, Args)]
 pub struct CmdDirectDecrypt {
-    /// Files in
+    /// File input
     #[arg(long, short = 'i')]
     pub file_in: PathBuf,
-    /// Files output
+    /// File output
     #[arg(long, short = 'o')]
     pub file_out: PathBuf,
     /// Remove source file
     #[arg(long, short = 'R')]
     pub remove_file: bool,
-    /// Key in HEX
+    /// Key in HEX (32 bytes)
     #[arg(long, short = 'k')]
     pub key: String,
 }
@@ -36,10 +36,12 @@ impl Drop for CmdDirectDecrypt {
 
 const DIRECT_ENCRYPT_MAGIC: &str = "e2c50001";
 
-// Format
-// [4 bytes] - magic 0xe2c50001
+// Direct decrypt file format:
+// [4 bytes] - magic 0xe2 0xc5 0x00 0x01
 // [32 bytes] - key digest
 // [12 bytes] - nonce
+// [n bytes] - ciphertext
+// [16 bytes] - tag
 pub fn direct_decrypt(cmd_direct_decrypt: CmdDirectDecrypt) -> XResult<()> {
     let key = opt_result!(hex::decode(&cmd_direct_decrypt.key), "Parse key failed: {}");
     if key.len() != 32 {