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Add Value Commitment operator #125

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41c4451
Add ValueCommitment modifier operator
OBrezhniev Feb 23, 2024
5d36799
Merge branch 'develop' into feature/valueCommitment
OBrezhniev Feb 26, 2024
9511cce
Merge branch 'develop' into feature/valueCommitment
OBrezhniev Apr 17, 2024
9483263
Unit tests for ValueCommitment
OBrezhniev May 1, 2024
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5 changes: 3 additions & 2 deletions circuits/lib/linked/linkId.circom
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@@ -1,11 +1,12 @@
pragma circom 2.1.5;

include "../../../node_modules/circomlib/circuits/poseidon.circom";
include "../../../node_modules/circomlib/circuits/comparators.circom";
include "../../../node_modules/circomlib/circuits/mux1.circom";
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volodymyr-basiuk marked this conversation as resolved.
include "../../../node_modules/circomlib/circuits/poseidon.circom";

template LinkID() {
signal input claimHash;
signal input linkNonce;
signal input linkNonce; // private random nonce to make the commitment unique and secure

signal output out;

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4 changes: 3 additions & 1 deletion circuits/lib/query/modifiers.circom
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Expand Up @@ -7,6 +7,7 @@ include "../../../node_modules/circomlib/circuits/mux4.circom";
/*
Modifier/computation operators:
16 - selective disclosure (16 = 10000 binary)
17 - value commitment (17 = 10001 binary)
*/

// modifierValidatorOutputSelector validates modifier operation and selects output value
Expand All @@ -24,7 +25,8 @@ template modifierValidatorOutputSelector() {
modifierOpValid.s <== [opBits[0], opBits[1], opBits[2], opBits[3]];
modifierOpValid.c <== [
1, // valid operator: 16 - selective disclosure (16-16 = index 0)
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
1, // valid operator: 17 - value commitment (17-1 = index 1)
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
];

ForceEqualIfEnabled()(
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8 changes: 7 additions & 1 deletion circuits/lib/query/processQueryWithModifiers.circom
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Expand Up @@ -3,6 +3,7 @@ pragma circom 2.1.1;
include "../../../node_modules/circomlib/circuits/comparators.circom";
include "query.circom";
include "modifiers.circom";
include "valueCommitment.circom";
include "../utils/claimUtils.circom";
include "../utils/arraySizeValidator.circom";

Expand All @@ -18,6 +19,7 @@ template ProcessQueryWithModifiers(claimLevels, maxValueArraySize){
signal input operator;
signal input value[maxValueArraySize];
signal input valueArraySize;
signal input commitNonce;

signal input issuerClaim[8];
signal input merklized;
Expand Down Expand Up @@ -101,6 +103,9 @@ template ProcessQueryWithModifiers(claimLevels, maxValueArraySize){
// selective disclosure
// no need to calc anything, fieldValue is just passed as an output

// value commitment
signal valueCommitment <== ValueCommitment()(fieldValue, commitNonce);

/////////////////////////////////////////////////////////////////
// Modifier Operator Validation & Output Preparation
/////////////////////////////////////////////////////////////////
Expand All @@ -110,7 +115,8 @@ template ProcessQueryWithModifiers(claimLevels, maxValueArraySize){
operator <== operator,
modifierOutputs <== [
fieldValue, // 16 - selective disclosure (16-16 = index 0)
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 // 17-31 - not used
valueCommitment, // 17 - value commitment (17-16 = index 1)
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 // 18-31 - not used
]
);
}
1 change: 1 addition & 0 deletions circuits/lib/query/query.circom
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Expand Up @@ -23,6 +23,7 @@ include "comparators.circom";
11 - exist
Modifier/computation operators:
16 - selective disclosure (16 = 10000 binary)
17 - value commitment (17 = 10001 binary)
*/

// Query template works only with Query operators (0-15), for the rest returns 0
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27 changes: 27 additions & 0 deletions circuits/lib/query/valueCommitment.circom
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@@ -0,0 +1,27 @@
pragma circom 2.1.1;

include "../../../node_modules/circomlib/circuits/mux1.circom";
include "../../../node_modules/circomlib/circuits/comparators.circom";
include "../../../node_modules/circomlib/circuits/poseidon.circom";

/**
Value commitment circuit allows to commit to a specific value and then
reveal it later or use such a commitment in another circuits to prove that
multiple circuits work with the same value without revealing it.
*/

template ValueCommitment() {
signal input value;
signal input commitNonce; // private random nonce to make the commitment unique and secure

signal output out;

signal isNonceZero <== IsZero()(commitNonce);

signal commit <== Poseidon(2)([value, commitNonce]);

@vmidyllic vmidyllic Feb 26, 2024

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Looks like I can receive the same commitment if I have another field with the same value and provide the same commitment outside. (I want to prove that I have the same date of birth in the different creds, but I can hack and prove that some another date that I have in other credential is equal to expected, but it is not the same meaning.

@OBrezhniev OBrezhniev Mar 7, 2024

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It's not a hack. Maybe user wants to prove to verifier that on his day of birth there was a sun eclipse. It's ok.
We don't have a way to check meaning of fields and we shouldn't. User needs to check what verifier asks from him - does it make sense.


out <== Mux1()(
[commit, 0],
isNonceZero
);
}
4 changes: 3 additions & 1 deletion circuits/linked/multiQuery.circom
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Expand Up @@ -26,6 +26,7 @@ template LinkedMultiQuery(N, claimLevels, maxValueArraySize) {
signal input operator[N];
signal input value[N][maxValueArraySize];
signal input valueArraySize[N];
signal input commitNonce[N];

// Outputs
signal output linkID;
Expand Down Expand Up @@ -68,7 +69,7 @@ template LinkedMultiQuery(N, claimLevels, maxValueArraySize) {
/////////////////////////////////////////////////////////////////
for (var i=0; i<N; i++) {
operatorNotNoop[i] <== NOT()(IsZero()(operator[i]));

// output value only if modifier operation was selected
operatorOutput[i] <== ProcessQueryWithModifiers(claimLevels, maxValueArraySize)(
operatorNotNoop[i], // enabled
Expand All @@ -82,6 +83,7 @@ template LinkedMultiQuery(N, claimLevels, maxValueArraySize) {
operator[i],
value[i],
valueArraySize[i],
commitNonce[i],
issuerClaim,
merklized,
merklize.out
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2 changes: 2 additions & 0 deletions circuits/offchain/credentialAtomicQueryV3OffChain.circom
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Expand Up @@ -51,6 +51,7 @@ template credentialAtomicQueryV3OffChain(issuerLevels, claimLevels, maxValueArra
signal input operator;
signal input value[maxValueArraySize];
signal input valueArraySize;
signal input commitNonce;
signal input issuerClaim[8];

// MTP specific
Expand Down Expand Up @@ -224,6 +225,7 @@ template credentialAtomicQueryV3OffChain(issuerLevels, claimLevels, maxValueArra
operator,
value,
valueArraySize,
commitNonce,
issuerClaim,
merklized,
merklize.out
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2 changes: 2 additions & 0 deletions circuits/onchain/credentialAtomicQueryV3OnChain.circom
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Expand Up @@ -118,6 +118,7 @@ template credentialAtomicQueryV3OnChain(issuerLevels, claimLevels, maxValueArray
signal input operator;
signal input value[maxValueArraySize];
signal input valueArraySize;
signal input commitNonce;

// MTP specific
signal input issuerClaimMtp[issuerLevels];
Expand Down Expand Up @@ -232,6 +233,7 @@ template credentialAtomicQueryV3OnChain(issuerLevels, claimLevels, maxValueArray
operator <== operator,
value <== value,
valueArraySize <== valueArraySize,
commitNonce <== commitNonce,
issuerClaim <== issuerClaim,
issuerClaimMtp <== issuerClaimMtp,
issuerClaimClaimsTreeRoot <== issuerClaimClaimsTreeRoot,
Expand Down