CustomProtectedInputStream.create asynchronous method

Article
05/31/2018

Asynchronously creates an InputStream for reading protected content.

Opens the specified serialized policy and creates a protected stream that can be used to decrypt the actual content. For more information, see the Remarks section of this topic.

Signature

public static IAsyncControl create(
                                       UserPolicy userPolicy,
                                       InputStream inputStream,
                                       long protectedContentLength,
                                       CreationCallback<CustomProtectedInputStream> callback)
                             throws InvalidParameterException

Parameters

Name	Datatype	Notes
userPolicy	UserPolicy	The custom protection policy.
inputStream	InputStream	The input stream with the protected content. The next bytes of available data in inputStream (i.e., those returned via the next call to inputStream.Read()) should contain the beginning of the stream's protected content. inputStream should have protectedContentLength bytes of contiguous protected content available.
protectedContentLength	long	The underlying length of the protected data contained within the stream.
callback	CreationCallback<CustomProtectedInputStream>>

Returns

IAsyncControl if an async operation is in progress else null is returned.

Throws

InvalidParameterException if no callback is available then onFailure can be called.

Defined in

CustomProtectedInputStream.java

Supported Platforms


Minimum supported OS version	Android 4.0.3 (API level 15)

Remarks

This method is asynchronous because it may require server / client communication. Your app specifies a current stream offset to protectedContentLength where the encrypted content is located in the backing stream.

If the range defined by the parameters current stream offset to protectedContentLength is not empty (i.e., protectedContentLength != 0), it must address an entire segment of encrypted content (i.e. it must start from block 0 (zero) and must have a final block in CBC case, or should be 16 bytes aligned in ECB case).

If the existing content ends at the end of the InputStream, your app can specify Long.MAX_VALUE as protectedContentLength.

The protectedContentLength parameter is needed only for the cases when there is a non-encrypted app specific content after the encrypted content (Multiple segments of protected data). When decrypting it, we need to know where the encrypted content ends. The protectedContentLength parameter is specified in terms of the encrypted content, i.e. it includes the size of the CBC padding.

Your app can use getEncryptedContentLength to determine the size of the encrypted content given the size of the original content.

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