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CryptoStream.ReadAsync Method (Byte[], Int32, Int32, CancellationToken)

.NET Framework 4.5

Reads a sequence of bytes from the current stream asynchronously, advances the position within the stream by the number of bytes read, and monitors cancellation requests.

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

public override Task<int> ReadAsync(
	byte[] buffer,
	int offset,
	int count,
	CancellationToken cancellationToken
)

Parameters

buffer
Type: System.Byte[]

The buffer to write the data into.

offset
Type: System.Int32

The byte offset in buffer at which to begin writing data from the stream.

count
Type: System.Int32

The maximum number of bytes to read.

cancellationToken
Type: System.Threading.CancellationToken

The token to monitor for cancellation requests. The default value is None.

Return Value

Type: System.Threading.Tasks.Task<Int32>
A task that represents the asynchronous read operation. The value of the task object's TResult parameter contains the total number of bytes read into the buffer. The result can be less than the number of bytes requested if the number of bytes currently available is less than the requested number, or it can be 0 (zero) if the end of the stream has been reached.

ExceptionCondition
ArgumentNullException

buffer is null.

ArgumentOutOfRangeException

offset or count is negative.

ArgumentException

The sum of offset and count is larger than the buffer length.

NotSupportedException

The stream does not support reading.

ObjectDisposedException

The stream has been disposed.

InvalidOperationException

The stream is currently in use by a previous read operation.

You must preface your call to ReadAsync with the await (C#) or Await (Visual Basic) operator to suspend execution of the method until the task is complete. For more information, see Asynchronous Programming with Async and Await (C# and Visual Basic).

If the operation is canceled before it completes, the returned task contains the Canceled value for the Status property.

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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