Security techniques and security mechanisms for wireless networks that transmit content such as advertisements. According to exemplary techniques, control messages comprising unrequested content (e.g., advertisement data) may be transmitted in response to a request from a client device, while in other exemplary techniques the control messages may be transmitted without any request from a client device. In some exemplary implementations, security mechanisms such as public key cryptography algorithms may be used to secure transmissions. In some of these techniques which implement public key cryptography, a user may be required to retrieve a public key from a source other than the wireless access point transmitting encrypted advertisements (e.g., a sign or terminal in a commercial entity transmitting such advertisements, or from a web service), such that the user may confirm that the encrypted content is from a source matching the retrieved public key and thus confirm the authenticity of a wireless access point.