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Adding some handling of block offsets for in place encryption/decryption

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This commit is contained in:
Uncled1023 2017-04-10 17:15:18 -07:00
parent 3490104980
commit 3bef7915dd
3 changed files with 21 additions and 8 deletions
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12
Utilities/Utilities/Crypto.cs
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@ -209,7 +209,7 @@ namespace Teknik.Utilities
// Process the stream and save the bytes to the output // Process the stream and save the bytes to the output
do do
{ {
int processedBytes = ProcessCipherBlock(cipher, input, chunkSize, output, cipherOffset, out bytesRead); int processedBytes = ProcessCipherBlock(cipher, input, 0, chunkSize, output, cipherOffset, out bytesRead);
cipherOffset += processedBytes; cipherOffset += processedBytes;
} }
while (bytesRead > 0); while (bytesRead > 0);
@ -234,7 +234,7 @@ namespace Teknik.Utilities
int bytesRead = 0; int bytesRead = 0;
do do
{ {
processedBytes = ProcessCipherBlock(cipher, input, chunkSize, buffer, 0, out bytesRead); processedBytes = ProcessCipherBlock(cipher, input, 0, chunkSize, buffer, 0, out bytesRead);
if (processedBytes > 0) if (processedBytes > 0)
{ {
// We have bytes, lets write them to the file // We have bytes, lets write them to the file
@ -268,17 +268,17 @@ namespace Teknik.Utilities
return cipher; return cipher;
} }
public static int ProcessCipherBlock(IBufferedCipher cipher, Stream input, int chunkSize, byte[] output, int outputOffset, out int bytesRead) public static int ProcessCipherBlock(IBufferedCipher cipher, Stream input, int inputOffset, int chunkSize, byte[] output, int outputOffset, out int bytesRead)
{ {
// Initialize buffer // Initialize buffer
byte[] buffer = new byte[chunkSize]; byte[] buffer = new byte[chunkSize + inputOffset];
// Read the next block of data // Read the next block of data
bytesRead = input.Read(buffer, 0, chunkSize); bytesRead = input.Read(buffer, 0, chunkSize + inputOffset);
if (bytesRead > 0) if (bytesRead > 0)
{ {
// process the cipher for the read block and add it to the output // process the cipher for the read block and add it to the output
return cipher.ProcessBytes(buffer, 0, bytesRead, output, outputOffset); return cipher.ProcessBytes(buffer, inputOffset, bytesRead - inputOffset, output, outputOffset);
} }
return 0; return 0;

2
Utilities/Utilities/ResponseHelper.cs
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@ -100,7 +100,7 @@ namespace Teknik.Utilities
{ {
bytesToRead = bytesRemaining; bytesToRead = bytesRemaining;
} }
processedBytes = AES.ProcessCipherBlock(cipher, stream, bytesToRead, buffer, 0, out bytesRead); processedBytes = AES.ProcessCipherBlock(cipher, stream, 0, bytesToRead, buffer, 0, out bytesRead);
if (processedBytes > 0) if (processedBytes > 0)
{ {
response.OutputStream.Write(buffer, 0, processedBytes); response.OutputStream.Write(buffer, 0, processedBytes);

15
Utilities/Utilities/StreamHelper.cs
View File

@ -24,9 +24,22 @@ namespace Teknik.Utilities
if (_Inner != null && CanRead) if (_Inner != null && CanRead)
{ {
int bytesRead = 0; int bytesRead = 0;
long startPosition = _Inner.Position;
int blockSize = _Cipher.GetBlockSize();
long blockOffset = (startPosition % blockSize);
// Determine if we are at the start of a block, or not
if (blockOffset != 0)
{
// We are not a multiple of the block size, so let's backup to get the current block
_Inner.Seek(startPosition - blockOffset, SeekOrigin.Begin);
}
// Process the cipher // Process the cipher
int processed = AES.ProcessCipherBlock(_Cipher, _Inner, count, buffer, offset, out bytesRead); int processed = AES.ProcessCipherBlock(_Cipher, _Inner, 0, count + (int)blockOffset, buffer, offset, out bytesRead);
// Adjust bytes read by the block offset
bytesRead -= (int)blockOffset;
if (processed < bytesRead) if (processed < bytesRead)
{ {