Like developer Derek Prior, I have found a number of websites have begun blocking paste operations into password fields, a particular pain on iOS. I’m not sure why, but the annoying upshot is that 1Password, which I use to generate (see Wolfram Alpha’s app for this as well) and store secure passwords, will fail to paste passwords into the proper field when copy/pasting from the app on your iPhone or iPad. You can still use their extension, as it fills the field instead of using a paste command. Any similar tool will have the same problem due to how web devs are blocking the onpaste event.
F**k it, we'll do it live!
Just drag the ‘allow pwpaste’ bookmark onto your bookmark bar and click it when a password paste fails. He, and I, recommend you use iCloud to sync it to mobile Safari, where you can then strip out the onpaste and then paste a password within mobile Safari.
It’s a clever workaround to an annoying problem. Thanks Derek!