//     -          IV <- metadata
//     -   SealedKey <- metadata
//     -   KeyEncKey := HMAC-SHA256(ClientKey, IV || 'SSE-C' || 'DAREv2-HMAC-SHA256' || bucket || '/' || object)
//     -   ObjectKey := DAREv2_Dec(KeyEncKey, SealedKey)
//     - object_data := DAREv2_Dec(ObjectKey, enc_object_data)
//     Output: object_data
//
// ## SSE-S3
//
// SSE-S3 can use either a master key or a KMS as root-of-trust.