Patent ID: 8392711

Claim:
A method comprising: transmitting, at a telecommunications node, secure messages with a first encryption key comprising a first string of symbols for a first time interval from instant b 1 to instant x 1 , wherein the first string of symbols is selected from a first key space having K 1 members, where K 1 is a natural number; and transmitting, at the telecommunications node, secure messages with a second encryption key comprising a second string of symbols for a second time interval from instant b 2 to instant x 2 , wherein the second string of symbols is selected from a second key space having K 2 members, where K 2 is a natural number; wherein x 2 >x 1 ; wherein b 2 >b 1 ; wherein b 2 <x 1 ; and wherein ln(K 2 )/(x 2 −b 2 )>ln(K 1 )/(x 1 −b 1 ).