Encryption can help prevent disclosure of data for a blind subpoena. But traditional encryption techniques pose limitations to the functionality of cloud applications. Traditional encryption ends up random, unformatted bit strings; the square pegs of our analogy. Using conventional encryption means we have encrypted data that simply cant replace plaintext data in requests made to the cloud. Using encryption to be a primitive that allows easy specification of the target format the ciphertexts produced by encryption should come out already formatted in the right shape.”]
Source: https://www.darkreading.com/cloud/data-encryption-in-the-cloud-square-pegs-in-round-holes