Contest data

README.md

@@ -1,6 +1,6 @@
 [![License](https://img.shields.io/github/license/JohnLCaron/egk-ec)](https://github.com/JohnLCaron/egk-ec/blob/main/LICENSE.txt)
 ![GitHub branch checks state](https://img.shields.io/github/actions/workflow/status/JohnLCaron/egk-ec/unit-tests.yml)
-![Coverage](https://img.shields.io/badge/coverage-90.6%25%20LOC%20(6958/7679)-blue)
+![Coverage](https://img.shields.io/badge/coverage-90.7%25%20LOC%20(6931/7639)-blue)
 
 # ElectionGuard-Kotlin Elliptic Curve
 

src/main/kotlin/org/cryptobiotic/eg/core/ElGamalCiphertext.kt

@@ -37,7 +37,7 @@ data class ElGamalCiphertext(val pad: ElementModP, val data: ElementModP) {
     fun decryptWithShares(publicKey: ElGamalPublicKey, shares: Iterable<ElementModP>): Int? {
         val sharesList = shares.toList()
         val context = compatibleContextOrFail(pad, data, publicKey.key, *(sharesList.toTypedArray()))
-        val allSharesProductM: ElementModP = with(context) { sharesList.multP() }
+        val allSharesProductM: ElementModP = context.multP(sharesList)
         val decryptedValue: ElementModP = this.data / allSharesProductM
         return publicKey.dLog(decryptedValue)
     }

src/main/kotlin/org/cryptobiotic/eg/core/ElGamalKeys.kt

@@ -60,7 +60,7 @@ class ElGamalPublicKey(inputKey: ElementModP) {
 class ElGamalSecretKey(val key: ElementModQ) {
     init {
         if (key < key.context.TWO_MOD_Q)
-            throw ArithmeticException("secret key must be in [2, Q)")
+            throw ArithmeticException("secret key must be in [2, Q) group=${key.context.javaClass.name}")
     }
     val negativeKey: ElementModQ = -key
     val context: GroupContext

src/main/kotlin/org/cryptobiotic/eg/core/GroupContext.kt

@@ -91,13 +91,13 @@ interface GroupContext {
      * Computes the sum of the given elements, mod q; this can be faster than using the addition
      * operation for large numbers of inputs.
      */
-    fun Iterable<ElementModQ>.addQ(): ElementModQ
+    fun addQ(cues: Iterable<ElementModQ>): ElementModQ
 
     /**
      * Computes the product of the given elements, mod p; this can be faster than using the
      * multiplication operation for large numbers of inputs.
      */
-    fun Iterable<ElementModP>.multP(): ElementModP
+    fun multP(pees: Iterable<ElementModP>): ElementModP
 
     /** Computes G^e mod p, where G is our generator */
     fun gPowP(exp: ElementModQ): ElementModP
@@ -263,18 +263,6 @@ fun compatibleContextOrFail(vararg elements: Element): GroupContext {
     return headContext
 }
 
-/**
- * Computes the sum of the given elements, mod q; this can be faster than using the addition
- * operation for large enough numbers of inputs.
- */
-fun GroupContext.addQ(vararg elements: ElementModQ) = elements.asIterable().addQ()
-
-/**
- * Computes the product of the given elements, mod p; this can be faster than using the
- * multiplication operation for large enough numbers of inputs.
- */
-fun GroupContext.multP(vararg elements: ElementModP) = elements.asIterable().multP()
-
 fun GroupContext.showOpCountResults(where: String): String {
     val opCounts = this.getAndClearOpCounts()
     return buildString {

src/main/kotlin/org/cryptobiotic/eg/core/ecgroup/EcElementModP.kt

@@ -24,7 +24,7 @@ class EcElementModP(val group: EcGroupContext, val ec: VecElementP): ElementModP
     }
 
     // TODO what does it mean to be in bounds ??
-    override fun inBounds(): Boolean = true // TODO("Not yet implemented")
+    override fun inBounds(): Boolean = true
 
     // TODO check this
     override fun isValidResidue(): Boolean {

src/main/kotlin/org/cryptobiotic/eg/core/ecgroup/EcGroupContext.kt

@@ -1,6 +1,5 @@
 package org.cryptobiotic.eg.core.ecgroup
 
-
 import org.cryptobiotic.eg.core.*
 import java.math.BigInteger
 import java.util.concurrent.atomic.AtomicInteger
@@ -77,23 +76,17 @@ class EcGroupContext(val name: String, useNative: Boolean = true): GroupContext
         return EcElementModQ(this, BigInteger.valueOf(i.toLong()))
     }
 
-    override fun Iterable<ElementModQ>.addQ(): ElementModQ {
-        return addQQ(this)
+    override fun addQ(cues: Iterable<ElementModQ>): ElementModQ {
+        val sum = cues.fold(BigInteger.ZERO) { a, b -> a.plus((b as EcElementModQ).element) }
+        return EcElementModQ(this, sum.mod(vecGroup.order))
     }
 
-    override fun Iterable<ElementModP>.multP(): ElementModP {
-        // TODO what if this.isEmpty() ?
-        return this.reduce { a, b -> a * b }
+    override fun multP(pees: Iterable<ElementModP>): ElementModP {
+       return pees.fold(ONE_MOD_P) { a, b -> a * b }
     }
 
     override fun randomElementModP(minimum: Int) = EcElementModP(this, vecGroup.randomElement())
 
-    fun addQQ(cues: Iterable<ElementModQ>): ElementModQ {
-        // TODO what if cues.isEmpty() ?
-        val sum = cues.fold(BigInteger.ZERO) { a, b -> a.plus((b as EcElementModQ).element) }
-        return EcElementModQ(this, sum.mod(vecGroup.order))
-    }
-
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
         if (javaClass != other?.javaClass) return false

src/main/kotlin/org/cryptobiotic/eg/core/intgroup/IntGroup.kt

@@ -65,7 +65,7 @@ class ProductionGroupContext(
     override fun isProductionStrength() = true
     override fun toString() : String = name
 
-    override val ONE_MOD_P
+    override val ONE_MOD_P : ElementModP
         get() = oneModP
 
     override val G_MOD_P
@@ -149,12 +149,17 @@ class ProductionGroupContext(
         else -> ProductionElementModQ(i.toBigInteger(), this)
     }
 
+    override fun addQ(cues: Iterable<ElementModQ>): ElementModQ {
+        val sum = cues.fold(BigInteger.ZERO) { a, b -> a.plus((b as ProductionElementModQ).element) }
+        return ProductionElementModQ(sum.mod(q), this)
+    }
+
+    /*
     override fun Iterable<ElementModQ>.addQ(): ElementModQ {
         val input = iterator().asSequence().toList()
 
-        // TODO why not return 0 ?
         if (input.isEmpty()) {
-            throw ArithmeticException("addQ not defined on empty lists")
+            return ZERO_MOD_Q
         }
 
         if (input.count() == 1) {
@@ -170,12 +175,18 @@ class ProductionGroupContext(
         return ProductionElementModQ(result, this@ProductionGroupContext)
     }
 
+     */
+
+    override fun multP(pees: Iterable<ElementModP>): ElementModP {
+        return pees.fold(ONE_MOD_P) { a, b -> a * b }
+    }
+
+    /*
     override fun Iterable<ElementModP>.multP(): ElementModP {
         val input = iterator().asSequence().toList()
 
-        // TODO why not return 1 ?
         if (input.isEmpty()) {
-            throw ArithmeticException("multP not defined on empty lists")
+            return ONE_MOD_P
         }
 
         if (input.count() == 1) {
@@ -191,6 +202,8 @@ class ProductionGroupContext(
         return ProductionElementModP(result, this@ProductionGroupContext)
     }
 
+     */
+
     override fun gPowP(exp: ElementModQ) = gModP powP exp
 
     override fun dLogG(p: ElementModP, maxResult: Int): Int? = dlogger.dLog(p, maxResult)
@@ -278,7 +291,7 @@ open class ProductionElementModP(internal val element: BigInteger, val groupCont
 
     override fun isValidResidue(): Boolean {
         groupContext.opCounts.getOrPut("exp") { AtomicInteger(0) }.incrementAndGet()
-        val residue = this.element.modPow(groupContext.q, groupContext.p) == groupContext.ONE_MOD_P.element
+        val residue = this.element.modPow(groupContext.q, groupContext.p) == groupContext.oneModP.element
         return inBounds() && residue
     }
 

src/main/kotlin/org/cryptobiotic/eg/decrypt/CipherDecryptor.kt

@@ -33,19 +33,19 @@ class CipherDecryptor(
         val decryptions = texts.mapIndexed { idx, text ->
 
             // lagrange weighted product of the shares, M = Prod(M_i^w_i) mod p; spec 2.0.0, eq 68
-            val weightedProduct = with (group) {
+            val weightedProduct = group.multP(
                 // for this idx, run over all the trustees
                 partialDecryptions.mapIndexed { tidx, pds ->
                     val trustee = decryptingTrustees[tidx]
                     val lagrange = lagrangeCoordinates[trustee.id()]!! // buildLagrangeCoordinates() guarentees exists
                     pds.partial[idx].Mi powP lagrange.lagrangeCoefficient
-                }.multP()
-            }
+                }
+            )
 
             // compute the collective challenge, needed for the collective proof; spec 2.0.0 eq 70
             val shares: List<PartialDecryption> = partialDecryptions.map { it.partial[idx] } // for this text, one from each trustee
-            val a: ElementModP = with(group) { shares.map { it.a }.multP() } // Prod(ai)
-            val b: ElementModP = with(group) { shares.map { it.b }.multP() } // Prod(bi)
+            val a: ElementModP = group.multP(shares.map { it.a }) // Prod(ai)
+            val b: ElementModP = group.multP(shares.map { it.b }) // Prod(bi)
 
             val collectiveChallenge = text.collectiveChallenge(extendedBaseHash, publicKey, a, b, weightedProduct)
 
@@ -115,7 +115,7 @@ class CipherDecryptor(
         challengeResponses: List<ElementModQ>, // across trustees for this decryption
     ): CipherDecryptionAndProof {
         // v = Sum(v_i mod q); spec 2.0.0 eq 76
-        val response: ElementModQ = with(group) { challengeResponses.map { it }.addQ() }
+        val response: ElementModQ = group.addQ(challengeResponses)
         val proof = ChaumPedersenProof(decryption.collectiveChallenge.toElementModQ(group), response)
         return CipherDecryptionAndProof(decryption, proof)
     }

src/main/kotlin/org/cryptobiotic/eg/decrypt/Guardians.kt

@@ -34,9 +34,9 @@ data class Guardians(val group : GroupContext, val guardians: List<Guardian>) {
             val guardian = guardianMap[guardianId]
                 ?: throw IllegalStateException("Guardians.getGexpP doesnt have guardian id = '$guardianId'")
 
-            with(group) {
-                guardians.map { calculateGexpPiAtL(it.guardianId, guardian.xCoordinate, it.coefficientCommitments()) }.multP()
-            }
+            group.multP(
+                guardians.map { calculateGexpPiAtL(it.guardianId, guardian.xCoordinate, it.coefficientCommitments()) }
+            )
         }
     }