Common use of Leave Protocol Clause in Contracts

Leave Protocol. ^ Such as Join protocol, we start with n members and assume that member Md leaves the group. The sponsor in this case is the rightmost leaf node of the subtree rooted at leaving member’s sibling node. First, if the number of leaving member’s sibling node is two, each member updates its key tree by deleting the leaf node corresponding to Md. Then the former sibling of Md is updated to replace Md’s parent node. Otherwise each member only deleting the leaf node corresponding to Md. The sponsor generates a new key share, computes all [key, bkey] pairs on the key-path up to the root, and broadcasts the new set of bkey. This allows all members to compute the new group key. In Fig. 3, if member M7 leaves the group, every remaining member deletes < 1, 2 > and < 2, 6 >. After updating the tree, the sponsor (M10) picks a new share K<2,8>, recomputes ▇<▇,▇>, ▇<▇,▇>, ▇▇<▇,▇> and BK<1,2>, and broadcasts the updated tree T10 with BK1∗0. Upon receiving the broadcast message, all members compute the group key. Note that M7 cannot compute the group key, though he knows all the bkeys, because his share is no longer a part of the group key.

Leave Protocol. ^ Such as Join protocol, we start with n members and assume that member Md leaves the group. The sponsor in this case is the rightmost leaf node of the subtree rooted at leaving member’s sibling node. First, if the number of leaving member’s sibling node is two, each member updates its key tree by deleting the leaf node corresponding to Md. Then the former sibling of Md is updated to replace Md’s parent node. Otherwise each member only deleting the leaf node corresponding to Md. The sponsor generates a new key share, computes all [key, bkey] pairs on the key-path up to the root, and broadcasts the new set of bkey. This allows all members to compute the new group key. In Fig. 3, if member M7 leaves the group, every remaining member deletes < 1, 2 > and < 2, 6 >. After updating the tree, the sponsor (M10) picks a new share K<2,8>, recomputes ▇<▇,▇K<1,2>, ▇<▇,▇K<0,0>, ▇▇<▇,▇^ BK<2,8> and BK<1,2>, and broadcasts the updated tree T10 with BK1∗0. Upon receiving the broadcast message, all members compute the group key. Note that M7 cannot compute the group key, though he knows all the bkeys, because his share is no longer a part of the group key.

Leave Protocol. ^ Such as Join protocolOnce again, we start with n members and assume that member Md leaves the group. The sponsor in this case is the rightmost leaf node of the subtree rooted at the leaving member’s sibling node. FirstFirst off, if the number of leaving member’s sibling node is twoas shown in Figure 4, each member updates its key tree by deleting the leaf node corresponding to Md. Then the The former sibling of Md is updated promoted to replace Md’s parent node. Otherwise each member only deleting the leaf node corresponding to Md. The sponsor generates a new key share, computes all [key, bkey] pairs on the key-key path up to the root, and broadcasts the new set of bkeybkeys. This allows all members to compute the new group key. In Fig. 3^ Looking at the setting in Figure 5, if member M7 M3 leaves the group, every remaining member deletes < (1, 2 > 1) and < (2, 6 >2). After updating the tree, the sponsor (M10M5) picks a new share K<2,8>K(2,3), recomputes ▇<▇,▇>K(1,1), ▇<▇,▇>K(0,0), ▇▇<▇,▇> BK(2,3) and BK<1,2>BK(1,1), and broadcasts the updated tree T10 T5 with BK1∗0. BK5∗. Upon receiving the broadcast message, all members compute the group key. Note that M7 M3 cannot compute the group key, though he it knows all the bkeys, because his its share is no longer a part of the group key. Step 1: Every member • • updates key tree by by removing the leaving member node and relevant parent node, removes all keys and bkeys from the leaf node related to the sponsor to the root node, Sponsor Mi additionally • broadcasts updated tree T^s including only bkeys. • generates new share and computes all [key, bkey] pairs on the key path, ^s s M T (BK∗) s −− − − − − −→ {M1..Mn} − {Md} Step 2: Every member computes the group key using T^s