Abstract: A computer-implemented method of encrypting a data object of variable size utilizing an inner encryption algorithm can take a variable size input and of outputting, as its output, an encrypted version of the variable size input. The method comprises compressing or encoding the data object in its totality to obtain a compressed or encoded version of the data object in a format compatible with the inner encryption algorithm, encrypting, by the inner encryption algorithm, the compressed or encoded version of the data object to obtain an encrypted version of the data object, and decompressing or decoding the encrypted version of the data object to obtain a decompressed or decoded version of the encrypted version of the data object, which constitutes a format-preserved encrypted version of the data object.