SabreTools/SabreTools.Hashing
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Fix efficient MD2

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This commit is contained in:
Matt Nadareski
2024-11-10 22:43:38 -05:00
parent e1c1c8322d
commit 6700f603f2
1 changed files with 21 additions and 16 deletions
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37
SabreTools.Hashing/MessageDigest/MD2.cs
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@@ -43,24 +43,29 @@ namespace SabreTools.Hashing.MessageDigest
/// <inheritdoc/>
public override void TransformBlock(byte[] data, int offset, int length)
{
// Figure out how much buffer is needed
int bufferLen = 16 - _byteCount;
// If there is buffer to fill and it will meet the limit
if (_byteCount > 0 && _byteCount + length >= 16)
{
// Fill the buffer from the input
for (int i = 0; i < 16 - _byteCount; i++)
for (int i = 0; i < bufferLen; i++)
{
// Add new character to buffer
_digest[16 + _byteCount + i] = data[offset + i];
_digest[32 + _byteCount + i] = (byte)(data[offset + i] ^ _digest[_byteCount + i]);
_digest[16 + _byteCount] = data[offset + i];
_digest[32 + _byteCount] = (byte)(data[offset + i] ^ _digest[_byteCount]);
// Update checksum register C and value L
_lastByte = _checksum[_byteCount] ^= MD2SBox[0xff & (data[offset + i] ^ _lastByte)];
// Increment i by one modulo 16
_byteCount = (byte)((_byteCount + 1) & 15);
}
// Set the new values
offset += 16 - _byteCount;
length -= 16 - _byteCount;
_byteCount = 0;
offset += bufferLen;
length -= bufferLen;
// Run the update
Update();
@@ -73,17 +78,19 @@ namespace SabreTools.Hashing.MessageDigest
for (int i = 0; i < 16; i++)
{
// Add new character to buffer
_digest[16 + i] = data[offset + i];
_digest[32 + i] = (byte)(data[offset + i] ^ _digest[i]);
_digest[16 + _byteCount] = data[offset + i];
_digest[32 + _byteCount] = (byte)(data[offset + i] ^ _digest[_byteCount]);
// Update checksum register C and value L
_lastByte = _checksum[i] ^= MD2SBox[0xff & (data[offset + i] ^ _lastByte)];
_lastByte = _checksum[_byteCount] ^= MD2SBox[0xff & (data[offset + i] ^ _lastByte)];
// Increment i by one modulo 16
_byteCount = (byte)((_byteCount + 1) & 15);
}
// Set the new values
offset += 16;
length -= 16;
_byteCount = 0;
// Run the update
Update();
@@ -96,15 +103,13 @@ namespace SabreTools.Hashing.MessageDigest
for (int i = 0; i < length; i++)
{
// Add new character to buffer
_digest[16 + _byteCount] = data[offset];
_digest[32 + _byteCount] = (byte)(data[offset] ^ _digest[i]);
_digest[16 + _byteCount] = data[offset + i];
_digest[32 + _byteCount] = (byte)(data[offset + i] ^ _digest[_byteCount]);
// Update checksum register C and value L
_lastByte = _checksum[_byteCount] ^= MD2SBox[0xff & (data[offset] ^ _lastByte)];
_lastByte = _checksum[_byteCount] ^= MD2SBox[0xff & (data[offset + i] ^ _lastByte)];
// Set the new values
offset++;
length--;
// Increment i by one modulo 16
_byteCount = (byte)((_byteCount + 1) & 15);
}
}