HTTP::cookie and decryption

If I use the AES::decrypt everything works fine but I understand from the wiki that the recommended method is HTTP::cookie decrypt

 

 

set ::key [AES::key 128]

 

 

if {[HTTP::cookie exists $ckname]} {

 

set encrypted [HTTP::cookie $ckname]

 

log "cookie sent by client is [HTTP::cookie $ckname]"

 

set decrypted [AES::decrypt $::key [b64decode $encrypted]]

 

log "decrypted cookie is $decrypted"

 

 

if {$decrypted eq $ckvalue} {

 

set forceauth 0

 

}

 

 

when HTTP_RESPONSE {

 

if {$authinsck eq 1} {

 

set encrypted [b64encode [AES::encrypt $::key $ckvalue]]

 

HTTP::cookie insert name "$ckname" value $encrypted domain $ckdomain

 

log "cookie sent by bigip is $encrypted"

 

}

 

}