The invention discloses a cross-platform information input and output 
protection system, comprising: 1. a cross-platform 
input method assistant 
software, which can be installed on a plurality of operating systems, is used for setting 
encryption / decryption keys and managing key information, encrypting data and decrypting data, 2. a cloud key cent, including 
key generation, 
key distribution and keymanagement modules, can synchronize data between the local key 
database and the remote key 
database system, 3. an 
encryption algorithm library, which can use or combine 
multiple encryption algorithms,4. a decryption 
algorithm library, which can automatically match and combine the decryption 
algorithm according to the parameters of the key, 5. an 
encryption module which can quickly encrypt the 
information data input into the buff area by the 
system of the device through calling the encryption function by the cross-platform 
input method assistant 
software, and 6. a decryption module, which cancall the decryption function to decrypt the 
information data in the 
system output buffer of the device quickly. The invention can effectively protect various kinds of privacy information of people innetwork communication, and has strong practicability.