Companies migration to the cloud implies protection of their sensitive and private data. Encryption is the key tool for business's confidential data protection against cyber security threats. However, storing the data in an encrypted format requires to address critical issues: performance, format and ordering of data, protection of encryption keys. Format-preserving encryption (FPE) allows to encrypt the data in such a way that the output (the ciphertext) is in the same format as the input (the plaintext). Thus, FPE schemes are revealed to be exceptionally useful since they permit to encrypt existing databases without changing their format. In this thesis, firstly, the most important FPE techniques are presented and analysed.