Fix GcmSivBlockCipher processing

2 files changed, 11 insertions, 2 deletions

diff --git a/crypto/src/crypto/modes/GcmSivBlockCipher.cs b/crypto/src/crypto/modes/GcmSivBlockCipher.cs
index 2ea8eef1d..63808a53a 100644
--- a/crypto/src/crypto/modes/GcmSivBlockCipher.cs
+++ b/crypto/src/crypto/modes/GcmSivBlockCipher.cs
@@ -875,8 +875,8 @@ namespace Org.BouncyCastle.Crypto.Modes
                     parent.gHASH(parent.theReverse);
 
                     /* Adjust counters */
-                    numProcessed += mySpace;
-                    myRemaining -= mySpace;
+                    numProcessed += BUFLEN;
+                    myRemaining -= BUFLEN;
                 }
 
                 /* If we have remaining data */
diff --git a/crypto/test/src/crypto/test/GcmSivTest.cs b/crypto/test/src/crypto/test/GcmSivTest.cs
index 16e53abdf..47f824db6 100644
--- a/crypto/test/src/crypto/test/GcmSivTest.cs
+++ b/crypto/test/src/crypto/test/GcmSivTest.cs
@@ -74,6 +74,15 @@ namespace Org.BouncyCastle.Crypto.Tests
                 pCipher.DoFinal(myOutput, 0);
                 IsTrue("Encryption mismatch", Arrays.AreEqual(myExpected, myOutput));
 
+                if (myData.Length >= 2)
+                {
+                    /* Repeat processing checking processBytes with non-empty internal buffer */
+                    pCipher.ProcessByte(myData[0], null, 0);
+                    pCipher.ProcessBytes(myData, 1, myData.Length - 1, null, 0);
+                    pCipher.DoFinal(myOutput, 0);
+                    IsTrue("Encryption mismatch", Arrays.AreEqual(myExpected, myOutput));
+                }
+
                 /* Re-initialise the cipher */
                 pCipher.Init(false, myParams);
                 pCipher.ProcessBytes(myOutput, 0, myOutput.Length, null, 0);