Abstract: A system may include an attack preventing creator module that is configured to create at least one attack preventing head block for a message having message elements in a tree structure with one or more of the message elements being signed, wherein the attack preventing header block includes structure specific information that comprises at least a digest value of a pre-order traversal list of the tree structure and for each signed message element a unique ID attribute, a depth, a parent's name and a parent's ID attribute. The system may include an attack preventing verifier module that is configured to verify the at least one attack preventing header block by comparing the structure specific information which can be derived from the message with the structure specific information carried by the first attack preventing header block.

Abstract: A system may include an attack preventing creator module that is configured to create at least one attack preventing head block for a message having message elements in a tree structure with one or more of the message elements being signed, wherein the attack preventing header block includes structure specific information that comprises at least a digest value of a pre-order traversal list of the tree structure and for each signed message element a unique ID attribute, a depth, a parent's name and a parent's ID attribute. The system may include an attack preventing verifier module that is configured to verify the at least one attack preventing header block by comparing the structure specific information which can be derived from the message with the structure specific information carried by the first attack preventing header block.

Abstract: In one embodiment the present invention includes a method for preventing attacks on auction sales of an online auction service provided by an auction server (A) within a network system, the method comprising an auction opening operation, a bid offering operation and an auction closing operation, wherein, in the auction closing operation, the auction server receives a notification from a trusted time server (T) providing a trusted time service at the closing time for submissions of a bid, sends the trusted time server (T) a message containing a hashed value calculated from all bid offers of at least one buyer which are successfully received, receives back from the trusted time server (T) a timestamp to declare that the period for online auction is closed, sends the timestamped message to the at least one buyer which verifies that a bid offer is included in the timestamped message.