1 files changed, 47 insertions, 0 deletions
diff --git a/Crypto/src/util/date/DateTimeUtilities.cs b/Crypto/src/util/date/DateTimeUtilities.cs
new file mode 100644
index 000000000..311ad5d37
--- /dev/null
+++ b/Crypto/src/util/date/DateTimeUtilities.cs
@@ -0,0 +1,47 @@
+using System;
+
+namespace Org.BouncyCastle.Utilities.Date
+{
+	public class DateTimeUtilities
+	{
+		public static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1);
+
+		private DateTimeUtilities()
+		{
+		}
+
+		/// <summary>
+		/// Return the number of milliseconds since the Unix epoch (1 Jan., 1970 UTC) for a given DateTime value.
+		/// </summary>
+		/// <param name="dateTime">A UTC DateTime value not before epoch.</param>
+		/// <returns>Number of whole milliseconds after epoch.</returns>
+		/// <exception cref="ArgumentException">'dateTime' is before epoch.</exception>
+		public static long DateTimeToUnixMs(
+			DateTime dateTime)
+		{
+			if (dateTime.CompareTo(UnixEpoch) < 0)
+				throw new ArgumentException("DateTime value may not be before the epoch", "dateTime");
+
+			return (dateTime.Ticks - UnixEpoch.Ticks) / TimeSpan.TicksPerMillisecond;
+		}
+
+		/// <summary>
+		/// Create a DateTime value from the number of milliseconds since the Unix epoch (1 Jan., 1970 UTC).
+		/// </summary>
+		/// <param name="unixMs">Number of milliseconds since the epoch.</param>
+		/// <returns>A UTC DateTime value</returns>
+		public static DateTime UnixMsToDateTime(
+			long unixMs)
+		{
+			return new DateTime(unixMs * TimeSpan.TicksPerMillisecond + UnixEpoch.Ticks);
+		}
+
+		/// <summary>
+		/// Return the current number of milliseconds since the Unix epoch (1 Jan., 1970 UTC).
+		/// </summary>
+		public static long CurrentUnixMs()
+		{
+			return DateTimeToUnixMs(DateTime.UtcNow);
+		}
+	}
+}