public void TestExp()
{
{
byte[] buf1 = new byte[16];
buf1[0] = 0x80;
byte[] buf2 = new byte[16];
for (int pow = 0; pow != 100; ++pow)
{
exp.ExponentiateX(pow, buf2);
Assert.IsTrue(Arrays.AreEqual(buf1, buf2));
mul.MultiplyH(buf1);
}
}
long[] testPow = new long[] { 10, 1, 8, 17, 24, 13, 2, 13, 2, 3 };
byte[][] testData = new byte[][] {
Hex.Decode("9185848a877bd87ba071e281f476e8e7"),
Hex.Decode("697ce3052137d80745d524474fb6b290"),
Hex.Decode("2696fc47198bb23b11296e4f88720a17"),
Hex.Decode("01f2f0ead011a4ae0cf3572f1b76dd8e"),
Hex.Decode("a53060694a044e4b7fa1e661c5a7bb6b"),
Hex.Decode("39c0392e8b6b0e04a7565c85394c2c4c"),
Hex.Decode("519c362d502e07f2d8b7597a359a5214"),
Hex.Decode("5a527a393675705e19b2117f67695af4"),
Hex.Decode("27fc0901d1d332a53ba4d4386c2109d2"),
Hex.Decode("93ca9b57174aabedf8220e83366d7df6"),
};
for (int i = 0; i != 10; ++i)
{
long pow = testPow[i];
byte[] data = Arrays.Clone(testData[i]);
byte[] expected = Arrays.Clone(data);
for (int j = 0; j < pow; ++j)
{
mul.MultiplyH(expected);
}
byte[] H_a = new byte[16];
exp.ExponentiateX(pow, H_a);
byte[] actual = multiply(data, H_a);
Assert.IsTrue(Arrays.AreEqual(expected, actual));
}
}
public int DoFinal(byte[] output, int outOff)
{
if (totalLength == 0)
{
InitCipher();
}
int num = bufOff;
if (forEncryption)
{
Check.OutputLength(output, outOff, num + macSize, "Output buffer too short");
}
else
{
if (num < macSize)
{
throw new InvalidCipherTextException("data too short");
}
num -= macSize;
Check.OutputLength(output, outOff, num, "Output buffer too short");
}
if (num > 0)
{
gCTRPartial(bufBlock, 0, num, output, outOff);
}
atLength += (uint)atBlockPos;
if (atLength > atLengthPre)
{
if (atBlockPos > 0)
{
gHASHPartial(S_at, atBlock, 0, atBlockPos);
}
if (atLengthPre != 0)
{
GcmUtilities.Xor(S_at, S_atPre);
}
long pow = (long)(totalLength * 8 + 127 >> 7);
byte[] array = new byte[16];
if (exp == null)
{
exp = new Tables1kGcmExponentiator();
exp.Init(H);
}
exp.ExponentiateX(pow, array);
GcmUtilities.Multiply(S_at, array);
GcmUtilities.Xor(S, S_at);
}
byte[] array2 = new byte[16];
Pack.UInt64_To_BE(atLength * 8, array2, 0);
Pack.UInt64_To_BE(totalLength * 8, array2, 8);
gHASHBlock(S, array2);
byte[] array3 = new byte[16];
cipher.ProcessBlock(J0, 0, array3, 0);
GcmUtilities.Xor(array3, S);
int num2 = num;
macBlock = new byte[macSize];
global::System.Array.Copy((global::System.Array)array3, 0, (global::System.Array)macBlock, 0, macSize);
if (forEncryption)
{
global::System.Array.Copy((global::System.Array)macBlock, 0, (global::System.Array)output, outOff + bufOff, macSize);
num2 += macSize;
}
else
{
byte[] array4 = new byte[macSize];
global::System.Array.Copy((global::System.Array)bufBlock, num, (global::System.Array)array4, 0, macSize);
if (!Arrays.ConstantTimeAreEqual(macBlock, array4))
{
throw new InvalidCipherTextException("mac check in GCM failed");
}
}
Reset(clearMac: false);
return(num2);
}
public int DoFinal(byte[] output, int outOff)
{
if (totalLength == 0)
{
InitCipher();
}
int extra = bufOff;
if (forEncryption)
{
Check.OutputLength(output, outOff, extra + macSize, "Output buffer too short");
}
else
{
if (extra < macSize)
{
throw new InvalidCipherTextException("data too short");
}
extra -= macSize;
Check.OutputLength(output, outOff, extra, "Output buffer too short");
}
if (extra > 0)
{
gCTRPartial(bufBlock, 0, extra, output, outOff);
}
atLength += (uint)atBlockPos;
if (atLength > atLengthPre)
{
/*
* Some AAD was sent after the cipher started. We determine the difference b/w the hash value
* we actually used when the cipher started (S_atPre) and the final hash value calculated (S_at).
* Then we carry this difference forward by multiplying by H^c, where c is the number of (full or
* partial) cipher-text blocks produced, and adjust the current hash.
*/
// Finish hash for partial AAD block
if (atBlockPos > 0)
{
gHASHPartial(S_at, atBlock, 0, atBlockPos);
}
// Find the difference between the AAD hashes
if (atLengthPre > 0)
{
GcmUtilities.Xor(S_at, S_atPre);
}
// Number of cipher-text blocks produced
long c = (long)(((totalLength * 8) + 127) >> 7);
// Calculate the adjustment factor
byte[] H_c = new byte[16];
if (exp == null)
{
exp = new Tables1kGcmExponentiator();
exp.Init(H);
}
exp.ExponentiateX(c, H_c);
// Carry the difference forward
GcmUtilities.Multiply(S_at, H_c);
// Adjust the current hash
GcmUtilities.Xor(S, S_at);
}
// Final gHASH
byte[] X = new byte[BlockSize];
Pack.UInt64_To_BE(atLength * 8UL, X, 0);
Pack.UInt64_To_BE(totalLength * 8UL, X, 8);
gHASHBlock(S, X);
// T = MSBt(GCTRk(J0,S))
byte[] tag = new byte[BlockSize];
cipher.ProcessBlock(J0, 0, tag, 0);
GcmUtilities.Xor(tag, S);
int resultLen = extra;
// We place into macBlock our calculated value for T
this.macBlock = new byte[macSize];
Array.Copy(tag, 0, macBlock, 0, macSize);
if (forEncryption)
{
// Append T to the message
Array.Copy(macBlock, 0, output, outOff + bufOff, macSize);
resultLen += macSize;
}
else
{
// Retrieve the T value from the message and compare to calculated one
byte[] msgMac = new byte[macSize];
Array.Copy(bufBlock, extra, msgMac, 0, macSize);
if (!Arrays.ConstantTimeAreEqual(this.macBlock, msgMac))
{
throw new InvalidCipherTextException("mac check in GCM failed");
}
}
Reset(false);
return(resultLen);
}
