Mixing secure and insecure data and operations at server database

A non-transitory computer readable medium having stored therein computer executable instructions for:

• at a server,
• receiving an encrypted query provided by a client as ciphertext generated by conversion of a floating number encoded in a bit string of a first size to another bit string of a second size, and encryption of the floating number in the another bit string, wherein recognizable terms generated of the user-generated query cannot be determined by the server, and the recognizable terms have a specific format of a the floating number,
• performing the query on encrypted data comprising a mix of regular data and secure data previously provided by the client, by manipulating the ciphertext input from the client to perform an arithmetic operation on the floating number while preserving its value, wherein the server is not provided with inputs and outputs associated with the recognizable terms, while preserving the specific format of the input floating numbers and without the server decrypting the ciphertext, and
• providing a result of the query to the client, wherein at least one of selection criteria of the query and identities of selected records of the query result cannot be determined by the server, wherein the result has the specific format, such that the client can decrypt the ciphertext to produce the floating number encoded in a bit string of the second size, and convert the floating number encoded in the bit string of the second size to another bit string of the first size,
• wherein the first size is different from the second size.