gadgetExamples::R1P_VerifyTransactionAmounts_Gadget Class Reference

Inheritance diagram for gadgetExamples::R1P_VerifyTransactionAmounts_Gadget:

Collaboration diagram for gadgetExamples::R1P_VerifyTransactionAmounts_Gadget:

Public Member Functions
void	generateConstraints ()
void	generateWitness ()
Public Member Functions inherited from gadgetlib2::R1P_Gadget
	R1P_Gadget (ProtoboardPtr pb)
virtual	~R1P_Gadget ()=0
virtual void	addRank1Constraint (const LinearCombination &a, const LinearCombination &b, const LinearCombination &c, const ::std::string &name)
Public Member Functions inherited from gadgetlib2::Gadget
	Gadget (ProtoboardPtr pb)
void	addUnaryConstraint (const LinearCombination &a, const ::std::string &name)
void	addRank1Constraint (const LinearCombination &a, const LinearCombination &b, const LinearCombination &c, const ::std::string &name)
void	enforceBooleanity (const Variable &var)
FElem &	val (const Variable &var)
FElem	val (const LinearCombination &lc)
FieldType	fieldType () const
bool	flagIsSet (const FlagVariable &flag) const

Friends
class	VerifyTransactionAmounts_Gadget

Additional Inherited Members
Protected Attributes inherited from gadgetlib2::Gadget
ProtoboardPtr	pb_

Detailed Description

Definition at line 458 of file tutorial.cpp.

Member Function Documentation

generateConstraints()

void gadgetExamples::R1P_VerifyTransactionAmounts_Gadget::generateConstraints ( )

virtual

Implements gadgetlib2::Gadget.

Definition at line 503 of file tutorial.cpp.

{
    addUnaryConstraint(
        sum(txInputAmounts_) - sum(txOutputAmounts_) - minersFee_,
        "sum(txInputAmounts) == sum(txOutputAmounts) + minersFee");
    // It would seem this is enough, but an adversary could cause an overflow of
    // one side of the equation over the field modulus. In fact, for every
    // input/output sum we will always find a miners' fee which will satisfy
    // this constraint! It is left as an exercise for the reader to implement
    // additional constraints (and witness) to check that each of the amounts
    // (inputs, outputs, fee) are between 0 and 21,000,000 * 1E8 satoshis.
    // Combine this with a maximum amount of inputs/outputs to disallow field
    // overflow.
    //
    // Hint: use Comparison_Gadget to create a gadget which compares a
    // variable's assigned value to a constant. Use a vector of these new
    // gadgets to check each amount. Don't forget to: (1) Wire these gadgets in
    // init() (2) Invoke the gadgets' constraints in generateConstraints() (3)
    // Invoke the gadgets' witnesses in generateWitness()
}

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generateWitness()

void gadgetExamples::R1P_VerifyTransactionAmounts_Gadget::generateWitness ( )

virtual

Reimplemented from gadgetlib2::Gadget.

Definition at line 524 of file tutorial.cpp.

{
    FElem sumInputs = 0;
    FElem sumOutputs = 0;
    for (const auto &inputAmount : txInputAmounts_) {
        sumInputs += val(inputAmount);
    }
    for (const auto &outputAmount : txOutputAmounts_) {
        sumOutputs += val(outputAmount);
    }
    val(minersFee_) = sumInputs - sumOutputs;
}

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Friends And Related Function Documentation

VerifyTransactionAmounts_Gadget

friend class VerifyTransactionAmounts_Gadget

friend

Definition at line 468 of file tutorial.cpp.

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The documentation for this class was generated from the following file:

• /home/runner/work/libsnark/libsnark/libsnark/gadgetlib2/examples/tutorial.cpp