1 files changed, 45 insertions, 0 deletions
diff --git a/crypto/src/openpgp/PgpPad.cs b/crypto/src/openpgp/PgpPad.cs
new file mode 100644
index 000000000..48f7f2f44
--- /dev/null
+++ b/crypto/src/openpgp/PgpPad.cs
@@ -0,0 +1,45 @@
+using System;
+
+namespace Org.BouncyCastle.Bcpg.OpenPgp
+{
+    /// <remarks>Padding functions.</remarks>
+    public sealed class PgpPad
+    {
+        private PgpPad()
+        {
+        }
+
+        public static byte[] PadSessionData(byte[] sessionInfo)
+        {
+            byte[] result = new byte[40];
+
+            Array.Copy(sessionInfo, 0, result, 0, sessionInfo.Length);
+
+            byte padValue = (byte)(result.Length - sessionInfo.Length);
+
+            for (int i = sessionInfo.Length; i != result.Length; i++)
+            {
+                result[i] = padValue;
+            }
+
+            return result;
+        }
+
+        public static byte[] UnpadSessionData(byte[] encoded)
+        {
+            byte padValue = encoded[encoded.Length - 1];
+
+            for (int i = encoded.Length - padValue; i != encoded.Length; i++)
+            {
+                if (encoded[i] != padValue)
+                    throw new PgpException("bad padding found in session data");
+            }
+
+            byte[] taggedKey = new byte[encoded.Length - padValue];
+
+            Array.Copy(encoded, 0, taggedKey, 0, taggedKey.Length);
+
+            return taggedKey;
+        }
+    }
+}