Feature request: add option to immediately validate ciphertext by decrypting it

When encrypting data to create an encrypted message, some customers may want to immediately attempt a decryption of the data before returning it in order to confirm that the ciphertext is valid and can be decrypted. We could offer this as a built-in option of the ESDK; during encrypt, we internally decrypt the encrypted message before returning it.

We'll have to think a bit about the API here to come up with something that works for all supported languages. See one possible approach here: https://github.com/aws/aws-encryption-sdk-java/pull/402

See also: https://github.com/aws/aws-encryption-sdk-java/issues/279

Start by reading the possible approach in aws-encryption-sdk-java pull request #402 and the related issue #279. Compare the proposed behavior across supported languages and define an API that enables decryption during encryption, with completion meaning the returned ciphertext has been successfully validated.

Written by the indexing model from the issue text.