Abstract: The disclosure proposes a format-preserving encryption method based on a stream cipher. In this method, the first three digits of an area code are encrypted by segmenting a phone number, creating mapping rules, and establishing an area code permutation table for the first three digits of the area code, thereby ensuring a legality of an encryption result; an accuracy of encryption and decryption is ensured by performing an XOR operation on a key stream generated from the ZUC algorithm (i.e., Zu Chongzhi's algorithm) and the last seven or eight digits of the phone number, combining a modulo operation to achieve conformal encryption, and introducing a Lagrange interpolation formula. This method securely and effectively realizes a consistency and legitimacy of data formats before and after encryption, and well hides statistical characteristics of plaintext, so that data is protected during a transmission process without changing the formats.

Abstract: The disclosure proposes a format-preserving encryption method based on a stream cipher. In this method, the first three digits of an area code are encrypted by segmenting a phone number, creating mapping rules, and establishing an area code permutation table for the first three digits of the area code, thereby ensuring a legality of an encryption result; an accuracy of encryption and decryption is ensured by performing an XOR operation on a key stream generated from the ZUC algorithm (i.e., Zu Chongzhi's algorithm) and the last seven or eight digits of the phone number, combining a modulo operation to achieve conformal encryption, and introducing a Lagrange interpolation formula. This method securely and effectively realizes a consistency and legitimacy of data formats before and after encryption, and well hides statistical characteristics of plaintext, so that data is protected during a transmission process without changing the formats.