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Exception testing for CTS mode #26

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Exception testing for CTS mode #26

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8 changes: 7 additions & 1 deletion core/src/main/java/org/bouncycastle/crypto/modes/CTSBlockCipher.java
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Original file line number Diff line number Diff line change
Expand Up @@ -22,8 +22,9 @@ public class CTSBlockCipher
public CTSBlockCipher(
BlockCipher cipher)
{
if ((cipher instanceof OFBBlockCipher) || (cipher instanceof CFBBlockCipher))
if ((cipher instanceof OFBBlockCipher) || (cipher instanceof CFBBlockCipher) || (cipher instanceof SICBlockCipher))
{
// TODO: This is broken - need to introduce marker interface to differentiate block cipher primitive from mode?
throw new IllegalArgumentException("CTSBlockCipher can only accept ECB, or CBC ciphers");
}

Expand Down Expand Up @@ -239,6 +240,11 @@ public int doFinal(
}
else
{
if (bufOff < blockSize)
{
throw new DataLengthException("need at least one block of input for CTS");
}

byte[] lastBlock = new byte[blockSize];

if (cipher instanceof CBCBlockCipher)
Expand Down
65 changes: 65 additions & 0 deletions core/src/test/java/org/bouncycastle/crypto/test/CTSTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,12 +3,15 @@
import org.bouncycastle.crypto.BlockCipher;
import org.bouncycastle.crypto.BufferedBlockCipher;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.InvalidCipherTextException;
import org.bouncycastle.crypto.engines.AESEngine;
import org.bouncycastle.crypto.engines.DESEngine;
import org.bouncycastle.crypto.engines.SkipjackEngine;
import org.bouncycastle.crypto.modes.CBCBlockCipher;
import org.bouncycastle.crypto.modes.CTSBlockCipher;
import org.bouncycastle.crypto.modes.OldCTSBlockCipher;
import org.bouncycastle.crypto.modes.SICBlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;
import org.bouncycastle.util.encoders.Hex;
Expand Down Expand Up @@ -94,6 +97,66 @@ private void testOldCTS(
}
}

private void testExceptions() throws InvalidCipherTextException
{
BufferedBlockCipher engine = new CTSBlockCipher(new DESEngine());
CipherParameters params = new KeyParameter(new byte[engine.getBlockSize()]);
engine.init(true, params);

byte[] out = new byte[engine.getOutputSize(engine.getBlockSize())];

engine.processBytes(new byte[engine.getBlockSize() - 1], 0, engine.getBlockSize() - 1, out, 0);
try
{
engine.doFinal(out, 0);
fail("Expected CTS encrypt error on < 1 block input");
} catch(DataLengthException e)
{
// Expected
}

engine.init(true, params);
engine.processBytes(new byte[engine.getBlockSize()], 0, engine.getBlockSize(), out, 0);
try
{
engine.doFinal(out, 0);
} catch(DataLengthException e)
{
fail("Unexpected CTS encrypt error on == 1 block input");
}

engine.init(false, params);
engine.processBytes(new byte[engine.getBlockSize() - 1], 0, engine.getBlockSize() - 1, out, 0);
try
{
engine.doFinal(out, 0);
fail("Expected CTS decrypt error on < 1 block input");
} catch(DataLengthException e)
{
// Expected
}

engine.init(false, params);
engine.processBytes(new byte[engine.getBlockSize()], 0, engine.getBlockSize(), out, 0);
try
{
engine.doFinal(out, 0);
} catch(DataLengthException e)
{
fail("Unexpected CTS decrypt error on == 1 block input");
}

try
{
new CTSBlockCipher(new SICBlockCipher(new AESEngine()));
fail("Expected CTS construction error - only ECB/CBC supported.");
} catch(IllegalArgumentException e)
{
// Expected
}

}

public String getName()
{
return "CTS";
Expand Down Expand Up @@ -135,6 +198,8 @@ public void performTest()

testCTS(7, new CBCBlockCipher(new AESEngine()), new ParametersWithIV(new KeyParameter(aes128), new byte[16]), aes1Block, pstErrata);
testOldCTS(7, new CBCBlockCipher(new AESEngine()), new ParametersWithIV(new KeyParameter(aes128), new byte[16]), aes1Block, preErrata);

testExceptions();
}

public static void main(
Expand Down