Each LionShare peer has two credentials, a "client" certificate and a "server" certificate. The contents of these certificates are different in order to protect the user's privacy. LionShare's use cases stipulate that it should not be possible to share files anonymously. To search for files, one must authenticate and obtain certificates, but it should be possible, however, to search for files without giving away one's identity. This is the "pseudononymous" user ability adopted from Shibboleth[4].

Both the "client" and "server" certificates contain information about which institution issued the certificate (encoded in the Issuer field). In this regard, the "client" certificate acts like a SAML authentication assertion -- it is a digitally signed assertion that the user has authenticated, but it does not reveal the user's identity. The "server" certificate does contain the users's identity; its Subject field contains the user's userid (such as an eduPersonPrincipalName) in the CN field. The client certificate contains an opaque handle for the user. The client certificate is used to open an SSL session with the Attribute Authority, which uses the opaque handle to identify the user.