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Systems and methods for preventing spam

  • US 7,711,786 B2
  • Filed: 01/22/2008
  • Issued: 05/04/2010
  • Est. Priority Date: 08/06/2007
  • Status: Expired due to Fees
First Claim
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1. A spam-prevention method, comprising:

  • receiving, at an exchange entity for a recipient, an electronic message that includes a source address associated with a sender and a dynamic tag, wherein the dynamic tag includes a first dynamic code and a counter;

    locating a hashing function and a secret key;

    determining a second dynamic code using at least the hashing function, the secret key, and the counter of the dynamic tag;

    verifying the dynamic tag by matching the first dynamic code of the dynamic tag to the second dynamic code; and

    accepting the electronic message to an account of the recipient upon verifying at least the dynamic tag,wherein the sender is a non-qualified sender, wherein the dynamic tag is a dynamic passcode, wherein locating the hashing function and the secret key includes locating a system hashing function and a system key, and wherein the dynamic passcode is obtained by the non-qualified sender manually querying a public dynamic passcode provider,wherein the dynamic passcode provider is a Web server, and querying the dynamic passcode provider includes the non-qualified sender entering at least a static email address of the recipient and completing a human interactive proof, wherein the dynamic passcode is generated by the dynamic passcode provider applying the system hashing function to a concatenated string comprising at least a portion of the static email address of the recipient, the system key, and an incremental counter associated with the recipient,wherein the prior steps are performed by one or more computers.

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