|  |  | Router B receives Router A's digitally signed update and strips the digital signature from it. Router B decrypts the digital signature by using Router A's public key. Router B inputs the routing table update into the one-way hash algorithm, resulting in message digest B. Router B compares message digest A to message digest B. If they match, B has authenticated that the information came from router A, and can update the tables. If they do not match, the routing tables will not be updated.