  We introduce the distribution of a secret multipartite entangled state in a
real-world scenario as a quantum primitive. We show that in the presence of
noisy quantum channels (and noisy control operations) any state chosen from the
set of two-colorable graph states (CSS codewords) can be created with high
fidelity while it remains unknown to all parties. This is accomplished by
either blind multipartite entanglement purification, which we introduce in this
paper, or by multipartite entanglement purification of enlarged states, which
offers advantages over an alternative scheme based on standard channel
purification and teleportation. The parties are thus provided with a secret
resource of their choice for distributed secure applications.
