Protecting Key Exchange and Management Protocols Against Resource Clogging Attacks

Many cryptographic key exchange and management protocols involve computationally expensive operations, such as modular exponentia-tions, and are therefore vulnerable to resource clogging attacks. This paper overviews and discusses the basic principles and the rationale behind an anti-clogging mechanism that was originally designed and proposed to protect the Photuris Session Key Management Protocol against resource clogging attacks. The mechanism was later approved by the IETF IPsec WG to be included into the Internet Key Management Protocol (IKMP) or Internet Key Exchange (IKE) protocol respectively. The paper introduces and discusses the Photuris anti-clogging mechanism , derives some design considerations, and elaborates on possibilities to use similar techniques to improve an existing HTTP state management protocol and to protect TCP/IP implementations against TCP SYN ooding attacks.