Patent ID: 7437561

Claim:
A method of authenticating data transmitted in a digital transmission system, said method comprising the steps, in a device storing a plurality of keys, of: when the data comprises at least one identifier of a certificate to be revoked: receiving the data and at least one encrypted value determined for the data, wherein the encrypted value is determined using a key associated with at least a first encryption algorithm; processing the at least one encrypted value using a stored key from the plurality of keys, wherein the stored key is associated with the first encryption algorithm to obtain a resulting value; comparing the resulting value with the data to authenticate the data; and revoking the certificate corresponding to the at least one identifier; and when the data comprises at least one replacement root certificate: receiving said data and at least two encrypted values determined for the data, wherein the at least two encrypted values are determined for the data, and wherein each encrypted value is determined using a key corresponding to at least a second and a third encryption algorithm, respectively; processing each of the at least two encrypted values using one of the plurality of stored keys to obtain a plurality of resulting values, wherein each of the plurality of stored keys corresponds to one of the at least second and third the encryption algorithms; comparing each of the plurality of resulting values with the data to authenticate the data; and storing the replacement root certificate in a permanent memory.