How can I convert from hex to base64?
Use xxd with the -r argument (and possibly the -p argument) to convert from hex to plain binary/octets and base64 to convert the binary/octet form to base64.
For a file:
cat file.dat | xxd -r -p | base64
For a string of hex numbers:
echo "6F0AD0BFEE7D4B478AFED096E03CD80A" | xxd -r -p | base64
Well, it depends on the exact formatting of your data. But you can do it with a simple shell scripts:
echo "obase=10; ibase=16; `cat in.dat`" | bc | base64 > out.dat
Modify as needed depending on your data.