CreateEncryptor methods throw exception for incorrect feedback size
CreateDecryptor methods for AesCng and TripleDESCng now throw a CryptographicException when the object instance is being used with a CNG persisted (or named) key for Cipher Feedback (CFB) mode, with a feedback size other than eight (CFB8).
Previously, these classes allowed CFB128 (
AesCng) or CFB64 (
TripleDESCng) to be selected. However, if the key was a persisted key, then the computation was always done as if CFB8 was selected.
CreateDecryptor methods throw a CryptographicException when both of the following conditions are met:
- CFB128 or CFB64 mode is selected (that is, SymmetricAlgorithm.FeedbackSize is set to 128 or 64).
- The instance is backed by a persisted key.
Type of breaking change
This change can affect binary compatibility.
Reason for change
This change was introduced to indicate that the requested work cannot be performed correctly.
If you encounter this exception, consider switching from CFB128 or CFB64 to CFB8. Making that switch will produce results compatible with the behavior in previous releases.
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