Convert existing FTP C program to SFTP

Modify current FTP API IBM i Service Program written in C that uses FTPLIB to transfer files to remote locations. Program needs to be converted to support either standard FTP or SFTP. Freelancer can use either libSSH2 directly or interface with existing CURL service program. Note: CURL will have to be modified to support secure communications. Resulting service program must be written in C and run on IBM i series machine. Client will provide access to development/test environment. All changes and additions MUST be documented and commented. NDA and background check require.