Using value from pipe as password

how can this be modified to work:

echo 1 2 45 4 5 | openssl aes-128-cbc -a -salt -k $(awk '{print $3}')

any ideas?

if the above were to work as I envision it, the password that would decrypt the encrypted text would be:

echo "the encrypted text" | openssl aes-128-cbc -a -salt -k 45