Can you try modifying the value of the set commands as follows
Before : set key G:/CSM/xilinx/project/ip_encryption/keyfile.v After : set key G:\CSM\xilinx\project\ip_encryption\keyfile.v
Before :set rtlfiles G:/CSM/xilinx/project/ip_encryption/Add_IP.v After :set rtlfilesG:\CSM\xilinx\project\ip_encryption\Add_IP.v
The issue might be because of the hierarchy file path separator i.e. windows is seeing the value of set variable as name of a file and searchind it in CWD instead of going to the directory and searching for the file.