Systems and methods for performing a secure transaction provided. In one embodiment, the method for encrypting data is provided, comprising: selecting clear text data; selecting a symbol set corresponding to the clear text data; encrypting the clear text data using a key, the encrypting comprising the operations of: defining a first portion and a second portion of the clear text data, encrypting the second portion using the key to generate an encryption mask, and encrypting the clear text data by applying the encryption mask to the first portion using a modulus operation while preserving the second portion as unencrypted, thereby resulting in encrypted data comprising an encrypted first portion and an unencrypted second portion; and wherein the encrypted data has the same format as the clear text data, has the same length as the clear text data, and uses the symbol set of the clear text data.