A method at an enterprise server system (118, 120, 122) for negotiating a secure device-to-device communications channel between a first computing device and a second computing device, the enterprise server system being separated from a communication network by a firewall, the first computing device being associated with a first user and the second computing device being associated with a second user, the method comprising: receiving a first connection request comprising first address data, a first cryptographic key associated with the first computing device, and an identification of the second user, the first connection request being received over a first secure communications channel; receiving a second connection request comprising second address data and a second cryptographic key associated with the second computing device and an identification of the first user the second connection request being received over a second secure communications channel; determining, on the basis of an identity of the first user and an identity of the second user, that the secure device-to-device communication channel is permitted and, dependent on a determination that the secure device-to-device communication channel is permitted: sending first connection data to the first computing device over the first secure communications channel; and sending second connection data to the second computing device over the second secure communications channel; wherein the first connection data comprises the second address data and second cryptographic key, and the second connection data comprises the first address data and first cryptographic key, the first and second connection data being for use in enabling establishment of the secure device-to-device communications channel between the first computing device and the second computing device. receiving a first connection request comprising first address data, a first cryptographic key associated with the first computing device, and an identification of the second user, the first connection request being received over a first secure communications channel; receiving a second connection request comprising second address data and a second cryptographic key associated with the second computing device and an identification of the first user the second connection request being received over a second secure communications channel; determining, on the basis of an identity of the first user and an identity of the second user, that the secure device-to-device communication channel is permitted and, dependent on a determination that the secure device-to-device communication channel is permitted: sending first connection data to the first computing device over the first secure communications channel; and sending second connection data to the second computing device over the second secure communications channel; wherein the first connection data comprises the second address data and second cryptographic key, and the second connection data comprises the first address data and first cryptographic key, the first and second connection data being for use in enabling establishment of the secure device-to-device communications channel between the first computing device and the second computing device. sending first connection data to the first computing device over the first secure communications channel; and sending second connection data to the second computing device over the second secure communications channel; wherein the first connection data comprises the second address data and second cryptographic key, and the second connection data comprises the first address data and first cryptographic key, the first and second connection data being for use in enabling establishment of the secure device-to-device communications channel between the first computing device and the second computing device.