At BelFOSS 2017 Ciaran Molloy and Jamie Bentham described the Smart Identity contract being developed at Deloitte Digital for the Ethereum blockchain. Jamie and Ciaran follwed up by letting us know the code has been released on GitHub under an Apache license.
Smart Identity uses the Ethereum blockchain to represent an identity using a smart contract, attributes can be added by the identity owner and are stored in hash form. Attributes can be endorsed by any user, this is done by storing a corresponding endorsement hash against the attribute hash. Endorsements are revocable and are considered current if not revoked.