Patent ID: 7886147

Claim:
A method of file conversion by a converter, comprising: receiving a file from a user at a client location, encrypted using a public key of the converter, where the converter is external to the client location; decrypting the file using a private key of the converter; converting the file format of the decrypted file at the converter, the decrypted file being stored in an allotted location in a memory of the converter for which read-only access to the stored decrypted file is provided, the memory being monitored for an attempt to access at least one memory location other than the allotted memory location and the file format conversion being aborted by the converter upon detecting attempt to access at least one memory location other than the allotted memory location; encrypting the file, if converted, using a public key of the user; and sending the encrypted file to the user, decryptable using a private key of the user, wherein the converter monitors for the attempt to access the at least one memory location and aborts the file conversion during the decrypting and the encrypting, such that the converter can not duplicate the file received from the client location.