Communication across domains

1. A method comprising:

determining that data to be sent across domains by a computing device via an Iframe is to be confirmed by a user before sending, the determining including ascertaining that an intended recipient of the data is untrusted, the computing device does not control or recognize the intended recipient;

outputting in a user interface by the computing device a portion that is selectable by the user to confirm that the sending of the data is permitted before performance of the sending; and

sending a first secret by the computing device across the domains for receipt by the recipient in response to the user confirming that the sending of the data is permitted;

receiving a result of a function applied to the first secret and a second secret by the computing device from the recipient; and

communicating the data via a secure communication channel formed across the domains via the Iframe using the result and the second secret.

2. A method as described in claim 1 , wherein the determining includes ascertaining that the data contains personally identifiable information.

3. A method as described in claim 1 , wherein the determining includes ascertaining that an intended recipient of the data is a third-party site.

4. A method as described in claim 1 , wherein the outputting is performed via a web browser.

5. A method comprising:

determining that messages to be sent across domains by a sender are to be confirmed by a user before sending, the determining including ascertaining that a recipient of the data is untrusted, the sender does not control or recognize the recipient;

generating a portion for a user interface that is selectable by the user to confirm that communicating the messages is permitted before performance of the communicating;

sending a first secret by the sender for receipt by the recipient across the domains in response to the user confirming that communicating the messages is permitted;

receiving a result of a function applied to the first secret and a second secret by the sender from the recipient across the domains;

forming a secure communication channel across the domains via at least one Iframe using the result and the second secret; and

communicating the messages via the secure communication channel.

6. A method as described in claim 5 , wherein:

the first secret is configured as a cryptographic number from the sender to the recipient;

the second secret is configured as a cryptographic number from the recipient; and

the forming uses the result to communicate the messages.

7. A method as described in claim 6 , wherein the cryptographic numbers are random numbers.