This disclosure relates generally to systems and methods for masking and unmasking of sensitive data. The present systems and methods solve the problems of consistency of the data masking, by using a random index and a masked index with use of regular expression concept. An additional random key produce different masked data versions, however the original form of the sensitive data is achieved with any masked data version. Plurality of masked data versions are generated by masking the sensitive input dataset, where the plurality of masked data versions comprises same format of the sensitive input dataset. The generated masked data versions are secured and hard to predict the original form of the sensitive input dataset by authorized or unauthorized environments. Also, the present method consume less processing time, as the masking process and the unmasking process make operations on the indexes rather than with the original dataset.