SOFM allows the user to encrypt a file before uploading to the connected online storage service via Netsso.. Encryption takes place on the user’s computer (Non-encrypted data never leave the user’s computers). The file content is encrypted by the widely-used Advanced Encryption Standard algorithm with a key length of 256 bit (AES 256). For encryption of each file a unique random key (RK) of length 32 bytes is used. RK is generated on the user’s computer and never leaves it in plain form. RK is also encrypted by AES 256 and stored in the encrypted file. A unique random string of 40 human-readable characters is used as the password for encrypting RK (PRK). It is generated every time on the user’s computer when the user sets/ re-sets (changes) his Master Password (MP) and stored in the Netsso database encrypted by the MP like other user data. The length of RK and PRK is chosen in such a way never to reduce the strength of the algorithm being used.