Check threshold public key bit length

thresholdkey_generator.go

@@ -2,6 +2,7 @@ package paillier
 
 import (
 	"crypto/rand"
+	"errors"
 	"io"
 	"math/big"
 	"time"
@@ -54,13 +55,17 @@ func GetThresholdKeyGenerator(
 	totalNumberOfDecryptionServers int,
 	threshold int,
 	random io.Reader,
-) *ThresholdKeyGenerator {
+) (*ThresholdKeyGenerator, error) {
-	ret := new(ThresholdKeyGenerator)
+	if publicKeyBitLength < 18 {
-	ret.publicKeyBitLength = publicKeyBitLength // TODO: at least 32
+		return nil, errors.New("Public key bit length must be at least 18 bits")
-	ret.TotalNumberOfDecryptionServers = totalNumberOfDecryptionServers
+	}
-	ret.Threshold = threshold
+
-	ret.Random = random
+	generator := new(ThresholdKeyGenerator)
-	return ret
+	generator.publicKeyBitLength = publicKeyBitLength
+	generator.TotalNumberOfDecryptionServers = totalNumberOfDecryptionServers
+	generator.Threshold = threshold
+	generator.Random = random
+	return generator, nil
 }
 
 func (tkg *ThresholdKeyGenerator) generateSafePrimes() (*big.Int, *big.Int, error) {

thresholdkey_generator_test.go

@@ -2,6 +2,7 @@ package paillier
 
 import (
 	"crypto/rand"
+	"errors"
 	"math/big"
 	"reflect"
 	"testing"
@@ -11,8 +12,49 @@ var MockGenerateSafePrimes = func() (*big.Int, *big.Int, error) {
 	return big.NewInt(887), big.NewInt(443), nil
 }
 
+func TestCreateThresholdKeyGenerator(t *testing.T) {
+	var tests = map[string]struct {
+		keyLength     int
+		expectedError error
+	}{
+		"generator successfully created for 20 bit key length": {
+			keyLength: 20,
+		},
+
+		"generator successfully created for 18 bit key length": {
+			keyLength: 18,
+		},
+
+		"generator can't be created for 16 bit key length": {
+			keyLength:     16,
+			expectedError: errors.New("Public key bit length must be at least 18 bits"),
+		},
+	}
+
+	for testName, test := range tests {
+		t.Run(testName, func(t *testing.T) {
+			gen, err := GetThresholdKeyGenerator(test.keyLength, 4, 3, rand.Reader)
+
+			if !reflect.DeepEqual(test.expectedError, err) {
+				t.Fatalf(
+					"Unexpected error\nActual: %v\nExpected: %v",
+					err,
+					test.expectedError,
+				)
+			}
+
+			if test.expectedError == nil && gen == nil {
+				t.Fatal("Got nil generator, it should be successfully created")
+			}
+		})
+	}
+}
+
 func TestGenerateSafePrimesOfThresholdKeyGenerator(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	p, q, err := tkh.generateSafePrimes()
 	if err != nil {
@@ -22,21 +64,30 @@ func TestGenerateSafePrimesOfThresholdKeyGenerator(t *testing.T) {
 }
 
 func TestInitPandP1(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	tkh.initPandP1()
 	AreSafePrimes(tkh.p, tkh.p1, 16, t)
 }
 
 func TestInitQandQ1(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	tkh.initQandQ1()
 	AreSafePrimes(tkh.q, tkh.q1, 16, t)
 }
 
 func TestInitPsAndQs(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	tkh.initPsAndQs()
 
@@ -95,7 +146,10 @@ func TestInitD(t *testing.T) {
 }
 
 func TestInitNumerialValues(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 4, 3, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	if err := tkh.initNumerialValues(); err != nil {
 		t.Error(err)
@@ -103,7 +157,11 @@ func TestInitNumerialValues(t *testing.T) {
 }
 
 func TestGenerateHidingPolynomial(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 15, 10, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 15, 10, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	if err := tkh.initNumerialValues(); err != nil {
 		t.Error(err)
 	}
@@ -125,7 +183,11 @@ func TestGenerateHidingPolynomial(t *testing.T) {
 }
 
 func TestComputeShare(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 5, 3, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 5, 3, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tkh.nm = b(103)
 	tkh.polynomialCoefficients = []*big.Int{b(29), b(88), b(51)}
 	share := tkh.computeShare(2)
@@ -135,8 +197,11 @@ func TestComputeShare(t *testing.T) {
 }
 
 func TestCreateShares(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 100, 10, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 100, 10, rand.Reader)
-	tkh.Random = rand.Reader
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	if err := tkh.initNumerialValues(); err != nil {
 		t.Error(err)
 	}
@@ -162,14 +227,22 @@ func TestCreateViArray(t *testing.T) {
 }
 
 func TestGetThresholdKeyGenerator(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(50, 10, 6, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(50, 10, 6, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	if err := tkh.initNumerialValues(); err != nil {
 		t.Error(nil)
 	}
 }
 
 func TestGenerate(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 10, 6, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 10, 6, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tpks, err := tkh.Generate()
 	if err != nil {
 		t.Error(err)
@@ -195,7 +268,11 @@ func TestGenerate(t *testing.T) {
 }
 
 func TestComputeV(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 10, 6, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 10, 6, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tkh.n = b(1907 * 1823)
 	tkh.nSquare = new(big.Int).Mul(tkh.n, tkh.n)
 	for i := 0; i < 100; i++ {

thresholdkey_test.go

@@ -8,7 +8,11 @@ import (
 )
 
 func getThresholdPrivateKey() *ThresholdPrivateKey {
-	tkh := GetThresholdKeyGenerator(32, 10, 6, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 10, 6, rand.Reader)
+	if err != nil {
+		panic(err)
+	}
+
 	tpks, err := tkh.Generate()
 	if err != nil {
 		panic(err)
@@ -184,7 +188,11 @@ func TestupdateCprime(t *testing.T) {
 }
 
 func TestEncryptingDecryptingSimple(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 2, 1, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 2, 1, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tpks, err := tkh.Generate()
 	if err != nil {
 		t.Error(err)
@@ -205,7 +213,11 @@ func TestEncryptingDecryptingSimple(t *testing.T) {
 }
 
 func TestEncryptingDecrypting(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 2, 2, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 2, 2, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tpks, err := tkh.Generate()
 	if err != nil {
 		t.Error(err)
@@ -227,7 +239,11 @@ func TestEncryptingDecrypting(t *testing.T) {
 }
 
 func TestHomomorphicThresholdEncryption(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 2, 2, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 2, 2, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tpks, _ := tkh.Generate()
 
 	plainText1 := b(13)
@@ -278,7 +294,11 @@ func TestValidate(t *testing.T) {
 }
 
 func TestCombinePartialDecryptionsZKP(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 2, 2, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 2, 2, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tpks, err := tkh.Generate()
 	if err != nil {
 		t.Error(err)
@@ -311,7 +331,11 @@ func TestCombinePartialDecryptionsZKP(t *testing.T) {
 }
 
 func TestCombinePartialDecryptionsWith100Shares(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 100, 50, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 100, 50, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tpks, err := tkh.Generate()
 	if err != nil {
 		t.Error(err)
@@ -338,7 +362,11 @@ func TestCombinePartialDecryptionsWith100Shares(t *testing.T) {
 }
 
 func TestVerifyDecryption(t *testing.T) {
-	tkh := GetThresholdKeyGenerator(32, 2, 2, rand.Reader)
+	tkh, err := GetThresholdKeyGenerator(32, 2, 2, rand.Reader)
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	tpks, err := tkh.Generate()
 
 	pk := &tpks[0].ThresholdPublicKey