diff --git a/DigitalData.Core.Security/Config/AsymCryptParams.cs b/DigitalData.Core.Security/Config/AsymCryptParams.cs
index 13b658b..c4ef697 100644
--- a/DigitalData.Core.Security/Config/AsymCryptParams.cs
+++ b/DigitalData.Core.Security/Config/AsymCryptParams.cs
@@ -36,13 +36,28 @@ namespace DigitalData.Core.Security.Config
         /// </example>
         public string KeyNameSeparator { get; init; } = ":";
 
+        /// <summary>
+        ///This is the subtext of the pem file name. For the file to be automatically renewed, the name must be assigned to change periodically. For example, by default MM/2 will be refreshed every 2 months.
+        /// <br />
+        /// - <see cref="StringExtensions.ToTag(DateTime, string)" /> is used when converting to tag.
+        /// <br />
+        /// - If the format contains the "//" symbol, the method divides the numeric value derived from the left side of the format 
+        /// by the numeric value of the right side of the format string. For instance:
+        /// <br />
+        /// - If the date is 02.03.2024 and the format is "MM//2", it extracts the month (02), divides it by 2 (resulting in 1),
+        ///   and returns "1".
+        ///   <br />
+        /// - If the format does not contain "//", the method uses the default <see cref="DateTime.ToString"/> format.
+        /// <br />
+        /// This method provides a way to format the date based on typical or customized rules, including mathematical operations like division.
+        /// </summary>
+        public string DateTagFormat { get; init; } = "MM//2";
+
         public IEnumerable<RSADecryptor> Decryptors { get; init; } = new List<RSADecryptor>();
 
         public RSADecryptor? Vault { get; init; }
 
-        public AsymCryptParams()
-        {
-            AfterCreate += () =>
+        public AsymCryptParams() => AfterCreate += () =>
             {
                 // Create root folder if it does not exist
                 if (!Directory.Exists(PemDirectory))
@@ -53,7 +68,7 @@ namespace DigitalData.Core.Security.Config
                     // set default path
                     if (decryptor.IsPemNull)
                     {
-                        var file_name_params = new List<object> { decryptor.Issuer, decryptor.Audience, KeySizeInBits };
+                        var file_name_params = new List<object> { decryptor.Issuer, decryptor.Audience, KeySizeInBits, DateTime.Now.ToTag(DateTagFormat) };
                         if (decryptor.IsEncrypted)
                             file_name_params.Add(Secrets.Version);
 
@@ -77,6 +92,5 @@ namespace DigitalData.Core.Security.Config
                     }
                 }
             };
-        }
     }
 }
\ No newline at end of file
diff --git a/DigitalData.Core.Security/Config/StringExtensions.cs b/DigitalData.Core.Security/Config/StringExtensions.cs
index 716ff3d..379af2e 100644
--- a/DigitalData.Core.Security/Config/StringExtensions.cs
+++ b/DigitalData.Core.Security/Config/StringExtensions.cs
@@ -9,5 +9,76 @@
         public static byte[] ToBytes(this string str) => System.Text.Encoding.UTF8.GetBytes(str);
 
         public static string BytesToString(this byte[] bytes) => System.Text.Encoding.UTF8.GetString(bytes);
+
+        /// <summary>
+        /// Converts a <see cref="DateTime"/> to a formatted string based on the specified format string.
+        /// <br />
+        /// - If the format contains the "//" symbol, the method divides the numeric value derived from the left side of the format 
+        /// by the numeric value of the right side of the format string. For instance:
+        /// <br />
+        /// - If the date is 02.03.2024 and the format is "MM//2", it extracts the month (02), divides it by 2 (resulting in 1),
+        ///   and returns "1".
+        ///   <br />
+        /// - If the format does not contain "//", the method uses the default <see cref="DateTime.ToString"/> format.
+        /// <br />
+        /// This method provides a way to format the date based on typical or customized rules, including mathematical operations like division.
+        /// </summary>
+        /// <param name="date">The <see cref="DateTime"/> value to be formatted.</param>
+        /// <param name="format">The format string that dictates the formatting of the date. If the format includes the "//" symbol, 
+        /// it splits the string at "//" and divides the left-side value by the right-side value. The format string can include standard
+        /// <see cref="DateTime.ToString"/> format patterns.</param>
+        /// <returns>A string representation of the formatted date, or the result of the division operation if "//" is present in the format.</returns>
+        /// <exception cref="ArgumentException">Thrown if the format string is invalid, such as having an incorrect number of parts after "//".</exception>
+        /// <exception cref="DivideByZeroException">Thrown if the right side of the "//" contains a zero, resulting in division by zero.</exception>
+        /// <exception cref="FormatException">Thrown if either the left-side or right-side value of "//" cannot be parsed as an integer.</exception>
+        public static string ToTag(this DateTime date, string format)
+        {
+            if (format is not null && format.Contains("//"))
+            {
+                var subStrings = format.Split("//");
+
+                if (subStrings.Length != 2)
+                    throw new ArgumentException("Format is invalid. It must contain exactly one '//' separator.");
+
+                var formattedLeft = date.ToString(subStrings[0]);
+
+                if (!int.TryParse(formattedLeft, out var dateValue))
+                    throw new FormatException("The left-side value of the format could not be parsed to an integer.");
+
+                if (!int.TryParse(subStrings[1], out var mode))
+                    throw new FormatException("The right-side value of the format could not be parsed to an integer.");
+
+                if (mode == 0)
+                    throw new DivideByZeroException("Division by zero is not allowed.");
+
+                var result = dateValue / mode;
+                return result.ToString();
+            }
+
+            return date.ToString(format);
+        }
+
+        /// <summary>
+        /// Converts a <see cref="DateTime"/> to a formatted string based on the specified format string.
+        /// <br />
+        /// - If the format contains the "//" symbol, the method divides the numeric value derived from the left side of the format 
+        /// by the numeric value of the right side of the format string. For instance:
+        /// <br />
+        /// - If the date is 02.03.2024 and the format is "MM//2", it extracts the month (02), divides it by 2 (resulting in 1),
+        ///   and returns "1".
+        ///   <br />
+        /// - If the format does not contain "//", the method uses the default <see cref="DateTime.ToString"/> format.
+        /// <br />
+        /// This method provides a way to format the date based on typical or customized rules, including mathematical operations like division.
+        /// </summary>
+        /// <param name="date">The <see cref="DateOnly"/> value to be formatted. It will convert to DateTime to use the method shared with DateTime.</param>
+        /// <param name="format">The format string that dictates the formatting of the date. If the format includes the "//" symbol, 
+        /// it splits the string at "//" and divides the left-side value by the right-side value. The format string can include standard
+        /// <see cref="DateTime.ToString"/> format patterns.</param>
+        /// <returns>A string representation of the formatted date, or the result of the division operation if "//" is present in the format.</returns>
+        /// <exception cref="ArgumentException">Thrown if the format string is invalid, such as having an incorrect number of parts after "//".</exception>
+        /// <exception cref="DivideByZeroException">Thrown if the right side of the "//" contains a zero, resulting in division by zero.</exception>
+        /// <exception cref="FormatException">Thrown if either the left-side or right-side value of "//" cannot be parsed as an integer.</exception>
+        public static string ToTag(this DateOnly date, string format) => date.ToDateTime(new()).ToTag(format);
     }
 }
\ No newline at end of file