ssh-keygen defaults to RSA (for SSH protocol 2) and a 2048 bit key.
At this description of ssh
The supported ciphers are: 3des-cbc, aes128-cbc, aes192-cbc, aes256-cbc, aes128-ctr, aes192-ctr, aes256-ctr, arcfour128, arcfour256, arcfour, blow- fish-cbc, and cast128-cbc. The default is: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128, arcfour256,arcfour,aes192-cbc,aes256-cbc,aes128-ctr, aes192-ctr,aes256-ctr
Thus it appears ciphers are either 128 or 256 bit, if I infer from unitless numbers. What is the justification for the ciphers being shorter than the key?