PGP updates from bc-java

1 files changed, 33 insertions, 13 deletions

diff --git a/crypto/src/openpgp/PgpPad.cs b/crypto/src/openpgp/PgpPad.cs
index 48f7f2f44..227e31019 100644
--- a/crypto/src/openpgp/PgpPad.cs
+++ b/crypto/src/openpgp/PgpPad.cs
@@ -11,35 +11,55 @@ namespace Org.BouncyCastle.Bcpg.OpenPgp
 
         public static byte[] PadSessionData(byte[] sessionInfo)
         {
-            byte[] result = new byte[40];
-
-            Array.Copy(sessionInfo, 0, result, 0, sessionInfo.Length);
+            return PadSessionData(sessionInfo, true);
+        }
 
-            byte padValue = (byte)(result.Length - sessionInfo.Length);
+        public static byte[] PadSessionData(byte[] sessionInfo, bool obfuscate)
+        {
+            int length = sessionInfo.Length;
+            int paddedLength = ((length >> 3) + 1) << 3;
 
-            for (int i = sessionInfo.Length; i != result.Length; i++)
+            if (obfuscate)
             {
-                result[i] = padValue;
+                paddedLength = System.Math.Max(40, paddedLength);
             }
 
+            int padCount = paddedLength - length;
+            byte padByte = (byte)padCount;
+
+            byte[] result = new byte[paddedLength];
+            Array.Copy(sessionInfo, 0, result, 0, length);
+            for (int i = length; i < paddedLength; ++i)
+            {
+                result[i] = padByte;
+            }
             return result;
         }
 
         public static byte[] UnpadSessionData(byte[] encoded)
         {
-            byte padValue = encoded[encoded.Length - 1];
+            int paddedLength = encoded.Length;
+            byte padByte = encoded[paddedLength - 1];
+            int padCount = padByte;
+            int length = paddedLength - padCount;
+            int last = length - 1;
 
-            for (int i = encoded.Length - padValue; i != encoded.Length; i++)
+            int diff = 0;
+            for (int i = 0; i < paddedLength; ++i)
             {
-                if (encoded[i] != padValue)
-                    throw new PgpException("bad padding found in session data");
+                int mask = (last - i) >> 31;
+                diff |= (padByte ^ encoded[i]) & mask;
             }
 
-            byte[] taggedKey = new byte[encoded.Length - padValue];
+            diff |= paddedLength & 7;
+            diff |= (40 - paddedLength) >> 31;
 
-            Array.Copy(encoded, 0, taggedKey, 0, taggedKey.Length);
+            if (diff != 0)
+                throw new PgpException("bad padding found in session data");
 
-            return taggedKey;
+            byte[] result = new byte[length];
+            Array.Copy(encoded, 0, result, 0, length);
+            return result;
         }
     }
 }