Secure session capability using public-key cryptography without access to the private key

摘要

A server establishes a secure session with a client device where a private key used in the handshake when establishing the secure session is stored in a different server. During the handshake procedure, the server receives a premaster secret that has been encrypted using a public key bound with a domain for which the client device is attempting to establish a secure session with. The server transmits the encrypted premaster secret to the different server for decryption along with other information necessary to compute a master secret. The different server decrypts the encrypted premaster secret, generates the master secret, and transmits the master secret to the server. The server receives the master secret and continues with the handshake procedure including generating one or more session keys that are used in the secure session for encrypting and decrypting communication between the client device and the server.

主权项

1. A method in a first server for establishing a secure session with a client device, the method comprising:
receiving, from the client device, a Client Hello message that includes a first random value; in response to the received Client Hello message, transmitting a Server Hello message to the client device that includes a second random value; transmitting, to the client device, a Server Certificate message that includes one or more digital certificates; transmitting, to the client device, a Server Hello Done message; receiving, from the client device, a Client Key Exchange message that includes an encrypted premaster secret, wherein the first server does not have access to a private key that can decrypt the encrypted premaster secret; transmitting, to a second server that has access to the private key that can decrypt the encrypted premaster secret, the following:
the first random value,the second random value,the encrypted premaster secret, andan indication data that is to be used by the second server to identify the private key,wherein the first server and the second server are different servers; receiving, from the second server, a master secret that was generated using a function that takes as input at least in part the decrypted premaster secret, the first random value, and the second random value; receiving, from the client device, a first Change Cipher Spec message; receiving, from the client device, a first Finished message; generating, using the received master secret, a set of one or more session keys to be used in the secure session for encrypting and decrypting communication between the client device and the first server; transmitting to the client device, a second Change Cipher Spec message; and transmitting, to the client device, a second Finished message.