White Paper: Pricing Via Processing or Combatting Junk Mail by Cynthia Dwork & Moni Naor
In this paper, Dwork & Noar presented a computational technique for combatting junk mail in general controlling access to a shared resource.
The main idea is to require a user to compute a moderately hard, but not intractable function to gain access to the resource, thus preventing frivolous (not having any serious purpose or value)use.
They suggest the following three pricing functions
1. Extracting Square Roots
2. A Fiat-Shamir Based Scheme
3. An Ong-Schnorr-Shamir Based Scheme, or, Recycling Broken Signature Schemes.
The user desiring access to the resource would compute a moderately hard function of the request-id.
The pricing function may be chosen to have something like a trap door: given some additional information the computation would be considerably less expensive (it is called a shortcut).
The shortcut may be used by the resource manager to allocate cheap access to the resource, as the manager sees fit, by bypassing the control mechanism.
For example, in the case of electronic mail, the shortcut permits the post office to grant bulk mailings at a price chosen by the post office, circumventing the cost of directly evaluating the pricing function for each recipient.
In this paper, Dwork & Noar presented a computational technique for combatting junk mail in general controlling access to a shared resource.
The main idea is to require a user to compute a moderately hard, but not intractable function to gain access to the resource, thus preventing frivolous (not having any serious purpose or value)use.
They suggest the following three pricing functions
1. Extracting Square Roots
2. A Fiat-Shamir Based Scheme
3. An Ong-Schnorr-Shamir Based Scheme, or, Recycling Broken Signature Schemes.
The user desiring access to the resource would compute a moderately hard function of the request-id.
The pricing function may be chosen to have something like a trap door: given some additional information the computation would be considerably less expensive (it is called a shortcut).
The shortcut may be used by the resource manager to allocate cheap access to the resource, as the manager sees fit, by bypassing the control mechanism.
For example, in the case of electronic mail, the shortcut permits the post office to grant bulk mailings at a price chosen by the post office, circumventing the cost of directly evaluating the pricing function for each recipient.
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