Patent ID: 7391868

Claim:
A cryptographic unit of an entity in a secure communication system for enabling at least one subscriber A to generate a public key, said cryptographic unit being configured for: a) selecting a unique identity I A distinguishing said subscriber A; b) generating public key reconstruction data γ A of said subscriber A by mathematically combining public values obtained from respective private values of said entity and said subscriber A, to obtain a pair (I A , γ A ) serving as said subscriber A's implicit certificate; c) combining said implicit certificate (I A , γ A ) in accordance with a mathematical function F(I A , γ A ) to derive entity information f, and d) generating a value k A by binding said entity information f with private values of said entity and transmitting said value k A to said subscriber A to permit said subscriber A to generate a private key from said value k A , the private value of said subscriber A, and said implicit certificate; whereby said subscriber A's public key may be reconstructed from public information, said public key reconstruction data γ A , and said identity I A .