there is no encrypted tftp.

try scp or https if you are concerned about encryption..to see if your equipment supports it, type following:

router#copy ?

/erase Erase destination file system.

/noverify Don't verify image signature before reload.

/verify Verify image signature before reload.

archive: Copy from archive: file system

cns: Copy from cns: file system

flash: Copy from flash: file system

ftp: Copy from ftp: file system

http: Copy from http: file system

https: Copy from https: file system

ips-sdf Copy from current IPS signature configuration

null: Copy from null: file system

nvram: Copy from nvram: file system

pram: Copy from pram: file system

rcp: Copy from rcp: file system

running-config Copy from current system configuration

scp: Copy from scp: file system

startup-config Copy from startup configuration

system: Copy from system: file system

tftp: Copy from tftp: file system

xmodem: Copy from xmodem: file system

ymodem: Copy from ymodem: file system