Fixed recipient

How many recipients take part With most signature schemes, an initialization can be carried out with an arbitrary number of recipients. However, there are schemes where initialization is carried out with a fixed recipient. (For example, a signer may be a client of a bank and carry out initialization with the sole purpose of sending authenticated messages to the bank.) The set of possible numbers of recipients is called Recipients per init. The two above-mentioned cases are Recipients per init = ( wid Recipients per init = 1. ... 

Fixed recipient. There is only one recipient in the system, i.e., IW/ I = 1. Formally, this is expressed by Recipients total = 1. All the remaining parameters can then be Any, i.e., they can be omitted. 

Few recipients. If there are few recipients in the system overall or per initialization, it can be more efficient to use several copies of an efficient scheme for a fixed recipient than a general scheme. 

Recipient known in authentication. This means that the parameters idsji ign are 1-element subsets of ids t of the corresponding initialization. Such inputs can be useful if signers have some recipients to whom they send many authenticated messages, because some of the efficiency improvements for fixed recipients can be applied dynamically [FoPf91]. In these cases, the disputes do not depend on the recipient, i.e., idsg g = ids h. = Any. 

Schemes with more than one recipient per initialization (see Section 5.2.10, Dependence of Authentication on the Recipients ) are almost always memoryless at least, testing a new message must work no matter whether the earlier messages from the same signer had the same recipient or not. Similarly, courts are almost always memory-less . In contrast, the efficiency of schemes with fixed recipient or one recipient per initialization can often be improved by giving up memory-less receiving (see [FoPf91] or Section 10.6).

Fixed recipient or one recipient per initialization. With all existing fail-stop signature schemes, what one gains by this restriction is efficiency in authentication, in particular, in the algorithm test, because the recipient s entity can store information from previous signatures. On the other hand, this implies that a court s entity cannot use the same test for a signature as the recipient s entity, i.e., disputes are not constructed as above. 

The main variation is in the dependence on the recipients. Their role is similar to that of the risk bearers in fail-stop signature schemes To guarantee computational security for each recipient, even if many other participants are attacking, the entities of all recipients must take part in initialization. Hence initialization is much simpler if it is for a fixed recipient. 

As mentioned in Section 6.1.2, more efficient constructions exist for the case of a fixed recipient, which is rather important in practice (see Section 6.2). They can be seen as special variants of tree authentication that exploit the fact that the recipient s entity can store information about the current tree. Hence only one new leaf, instead of one complete branch, has to be sent and tested during each authentication, see Section 10.6. The complexity of fail-stop signature schemes with fixed recipient is therefore comparable to that of ordinary digital signature schemes. 

In the case with a fixed recipient, efficiency can be improved significantly, because the recipient s entity can store information from previously received signatures. 

The abbreviated names of the constructions mean bottom-up tree authentication (10.9), top-down tree authentication (10.13), top-down tree authentication with a small amount of private storage (10.19), the discrete-logarithm scheme with minimized secret key (10.22) without combination with tree authentication, and the construction with a list-shaped tree for a fixed recipient from Section 10.6. The first column of lower bounds is for standard fail-stop signature schemes (Sections 11.3 and 11.4), the second one for standard information-theoretically secure signature schemes (Section 11.5) here the length of a test key has been entered in the row with the public keys. 

Length of Bottom- up T( )-down Top-down -1- Improved discr. log. Fixed recipient Lower bound Info.-th. secure... 

Figure 1a. Principle of tissue microarray (TMA) analysis. Cylindrical cores are obtained from a number (up to 1,000) of individual formalin-fixed, paraffin-embedded tissue blocks. These are transferred to recipient TMA. Each TMA block can be sectioned up to 300 times. All resulting TMA slides have the same tissues in the same coordinate positions. The individual slides can be used for a variety of analyses saving labor and reagent costs while maintaining uniformity of assay.

A variable-dose plasma concentration-controlled approach to combination antiretroviral therapy (zidovudine, lamivudine, and indinavir) has been compared with conventional fixed-dose therapy in 40 patients in a randomized, 52-week, open trial (6). Significantly more concentration-controlled recipients achieved the desired concentrations for aU three drugs there was a good response in 15 of 16 concentration-controlled recipients compared with nine of 17 conventional regimen recipients. However, there was no difference in the occurrence... 

Provider-Led Demand-Side Subsidies Provided before Service Provision Provider-led demand-side subsidies transferred before service provision include cost-per-case contracts in which the provider receives a fixed subsidy for a specified number of services, capitation payments, and referral vouchers distributed by providers that entitle the recipient to goods or services provided by others. 

Transactions to transfer authenticated messages from one recipient to another in the sense that the certainty that one can win disputes in court is transferred. Such transfers can work arbitrarily often (arbitrary transferability) or a fixed, finite number of times (finite tranrferability). 

Message bound. To cover cases where only a fixed number of messages can be authenticated after an initialization, there must be an input parameter to select this number, say N. It is called the message bound. Its domain is a subset Message bounds of KJ °, where means that no upper bound exists. Recipients and courts input this number, too. ° To be prepared for complexity considerations, N is always input in unary representation. 

Recall that the recipient is fixed hence his entity can store the counter i. Furthermore, the notion of the i-th fail-stop signature is clearly defined in the fail-stop signature schemes that would be used here (and any fail-stop signature scheme could be modified in this way) Either a scheme with tree authentication would be used or the theoretical construction from [DaPP94], where as many keys have to be prepared as one intends to sign messages. 

Before the components of standard fail-stop signature schemes (in a conventional definition) are summarized in Definition 7.1, the specification parameters from Section 5.2.5 must be considered. Several of them have already been fixed for all standard fail-stop signature schemes, e.g., the set Dispute jresults and everything to do with sets of identities of recipients, because no dependence on the recipient is prescribed. Others cannot be seen in a conventional definition, such as Sign results. Two parameters remain, the message space and the set of message bounds. 

In a later analysis, however, Graversen (2004) calls into question the previously measured effect on private job training. The analysis shows very big variations in the effect for different individuals, and it is probably the strongest cash benefit recipients, who are able to find a job by themselves, that are offered private job training. The analysis was carried out as an advanced regression analysis, in which the employment effect for different types of individuals in different types of activation was compared. This is why the analysis cannot be compared with the above presented fixed-effect analysis. 

A benefit recipient gets feedback in the form of clear and fixed terms and conditions of the benefit receipt in advance - see for example the Personal Responsibility Agreement between TANF participants and the TANF agency and work, or activity, related incentives (such as the EITC, an income disregard, job retention services, transition benefits, and so on) making work pay. 

According to the Personal Responsibility and Work Opportunity Act (PRWOA) of 1996, the US states are obliged to achieve the fixed quotas in labour participation, to provide for supporting means (e.g. day care for children) and to secure the interest of public administration in integrating benefit recipients by offering... 

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