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package ristretto255
import (
"bytes"
"crypto/sha512"
"encoding/hex"
"encoding/json"
"math/big"
"testing"
"filippo.io/edwards25519/field"
)
// The encoding of the canonical generator.
var compressedRistrettoBasepoint, _ = hex.DecodeString("e2f2ae0a6abc4e71a884a961c500515f58e30b6aa582dd8db6a65945e08d2d76")
func TestRistrettoBasepointRoundTrip(t *testing.T) {
decodedBasepoint := &Element{}
err := decodedBasepoint.Decode(compressedRistrettoBasepoint)
if err != nil {
t.Fatal(err)
}
ristrettoBasepoint := (&Element{}).Base()
if decodedBasepoint.Equal(ristrettoBasepoint) != 1 {
t.Error("decode succeeded, but got wrong point")
}
roundtripBasepoint := decodedBasepoint.Encode(nil)
if !bytes.Equal(compressedRistrettoBasepoint, roundtripBasepoint) {
t.Error("decode<>encode roundtrip produced different results")
}
encodedBasepoint := ristrettoBasepoint.Encode(nil)
if !bytes.Equal(compressedRistrettoBasepoint, encodedBasepoint) {
t.Error("point encode produced different results")
}
}
func TestRistrettoRandomRoundtrip(t *testing.T) {
// TODO quickcheck
}
func TestRistrettoSmallMultiplesTestVectors(t *testing.T) {
var testVectors = [16]string{
// This is the identity point
"0000000000000000000000000000000000000000000000000000000000000000",
// This is the basepoint
"e2f2ae0a6abc4e71a884a961c500515f58e30b6aa582dd8db6a65945e08d2d76",
// These are small multiples of the basepoint
"6a493210f7499cd17fecb510ae0cea23a110e8d5b901f8acadd3095c73a3b919",
"94741f5d5d52755ece4f23f044ee27d5d1ea1e2bd196b462166b16152a9d0259",
"da80862773358b466ffadfe0b3293ab3d9fd53c5ea6c955358f568322daf6a57",
"e882b131016b52c1d3337080187cf768423efccbb517bb495ab812c4160ff44e",
"f64746d3c92b13050ed8d80236a7f0007c3b3f962f5ba793d19a601ebb1df403",
"44f53520926ec81fbd5a387845beb7df85a96a24ece18738bdcfa6a7822a176d",
"903293d8f2287ebe10e2374dc1a53e0bc887e592699f02d077d5263cdd55601c",
"02622ace8f7303a31cafc63f8fc48fdc16e1c8c8d234b2f0d6685282a9076031",
"20706fd788b2720a1ed2a5dad4952b01f413bcf0e7564de8cdc816689e2db95f",
"bce83f8ba5dd2fa572864c24ba1810f9522bc6004afe95877ac73241cafdab42",
"e4549ee16b9aa03099ca208c67adafcafa4c3f3e4e5303de6026e3ca8ff84460",
"aa52e000df2e16f55fb1032fc33bc42742dad6bd5a8fc0be0167436c5948501f",
"46376b80f409b29dc2b5f6f0c52591990896e5716f41477cd30085ab7f10301e",
"e0c418f7c8d9c4cdd7395b93ea124f3ad99021bb681dfc3302a9d99a2e53e64e",
}
basepointMultiple := (&Element{}).Zero()
ristrettoBasepoint := (&Element{}).Base()
for i := range testVectors {
// Grab the bytes of the encoding
encoding, err := hex.DecodeString(testVectors[i])
if err != nil {
t.Fatalf("#%d: bad hex encoding in test vector: %v", i, err)
}
// Decode the test vector to a ristretto255 element
decodedPoint := Element{}
err = decodedPoint.Decode(encoding)
if err != nil {
t.Fatalf("#%d: could not decode test vector: %v", i, err)
}
// Re-encode and check round trips
roundtripEncoding := decodedPoint.Encode(nil)
if !bytes.Equal(encoding, roundtripEncoding) {
t.Errorf("#%d: decode<>encode roundtrip failed", i)
}
// Check that the test vector encodes i * B
if basepointMultiple.Equal(&decodedPoint) != 1 {
t.Errorf("decoded small multiple %d * B is not %d * B", i, i)
}
computedEncoding := basepointMultiple.Encode(nil)
if !bytes.Equal(encoding, computedEncoding) {
t.Errorf("#%d: encoding computed value did not match", i)
}
// Ensure basepointMultiple = i * B in the next iteration
basepointMultiple.Add(basepointMultiple, ristrettoBasepoint)
}
}
func TestRistrettoBadEncodingsTestVectors(t *testing.T) {
var testVectors = []string{
// These are all bad because they're non-canonical field encodings.
"00ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
"f3ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
"edffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
// These are all bad because they're negative field elements.
"0100000000000000000000000000000000000000000000000000000000000000",
"01ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
"ed57ffd8c914fb201471d1c3d245ce3c746fcbe63a3679d51b6a516ebebe0e20",
"c34c4e1826e5d403b78e246e88aa051c36ccf0aafebffe137d148a2bf9104562",
"c940e5a4404157cfb1628b108db051a8d439e1a421394ec4ebccb9ec92a8ac78",
"47cfc5497c53dc8e61c91d17fd626ffb1c49e2bca94eed052281b510b1117a24",
"f1c6165d33367351b0da8f6e4511010c68174a03b6581212c71c0e1d026c3c72",
"87260f7a2f12495118360f02c26a470f450dadf34a413d21042b43b9d93e1309",
// These are all bad because they give a nonsquare x^2.
"26948d35ca62e643e26a83177332e6b6afeb9d08e4268b650f1f5bbd8d81d371",
"4eac077a713c57b4f4397629a4145982c661f48044dd3f96427d40b147d9742f",
"de6a7b00deadc788eb6b6c8d20c0ae96c2f2019078fa604fee5b87d6e989ad7b",
"bcab477be20861e01e4a0e295284146a510150d9817763caf1a6f4b422d67042",
"2a292df7e32cababbd9de088d1d1abec9fc0440f637ed2fba145094dc14bea08",
"f4a9e534fc0d216c44b218fa0c42d99635a0127ee2e53c712f70609649fdff22",
"8268436f8c4126196cf64b3c7ddbda90746a378625f9813dd9b8457077256731",
"2810e5cbc2cc4d4eece54f61c6f69758e289aa7ab440b3cbeaa21995c2f4232b",
// These are all bad because they give a negative xy value.
"3eb858e78f5a7254d8c9731174a94f76755fd3941c0ac93735c07ba14579630e",
"a45fdc55c76448c049a1ab33f17023edfb2be3581e9c7aade8a6125215e04220",
"d483fe813c6ba647ebbfd3ec41adca1c6130c2beeee9d9bf065c8d151c5f396e",
"8a2e1d30050198c65a54483123960ccc38aef6848e1ec8f5f780e8523769ba32",
"32888462f8b486c68ad7dd9610be5192bbeaf3b443951ac1a8118419d9fa097b",
"227142501b9d4355ccba290404bde41575b037693cef1f438c47f8fbf35d1165",
"5c37cc491da847cfeb9281d407efc41e15144c876e0170b499a96a22ed31e01e",
"445425117cb8c90edcbc7c1cc0e74f747f2c1efa5630a967c64f287792a48a4b",
// This is s = -1, which causes y = 0.
"ecffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
}
basepointMultiple := Element{}
basepointMultiple.Zero()
for i := range testVectors {
// Grab the bytes of the encoding
encoding, err := hex.DecodeString(testVectors[i])
if err != nil {
t.Fatalf("#%d: bad hex encoding in test vector: %v", i, err)
}
// Attempt decoding
decodedPoint := Element{}
err = decodedPoint.Decode(encoding)
if err == nil {
t.Fatalf("#%d: did not fail on bad encoding", i)
}
}
}
func TestRistrettoFromUniformBytesTestVectors(t *testing.T) {
inputs := []string{
"Ristretto is traditionally a short shot of espresso coffee",
"made with the normal amount of ground coffee but extracted with",
"about half the amount of water in the same amount of time",
"by using a finer grind.",
"This produces a concentrated shot of coffee per volume.",
"Just pulling a normal shot short will produce a weaker shot",
"and is not a Ristretto as some believe.",
}
elements := []string{
"3066f82a1a747d45120d1740f14358531a8f04bbffe6a819f86dfe50f44a0a46",
"f26e5b6f7d362d2d2a94c5d0e7602cb4773c95a2e5c31a64f133189fa76ed61b",
"006ccd2a9e6867e6a2c5cea83d3302cc9de128dd2a9a57dd8ee7b9d7ffe02826",
"f8f0c87cf237953c5890aec3998169005dae3eca1fbb04548c635953c817f92a",
"ae81e7dedf20a497e10c304a765c1767a42d6e06029758d2d7e8ef7cc4c41179",
"e2705652ff9f5e44d3e841bf1c251cf7dddb77d140870d1ab2ed64f1a9ce8628",
"80bd07262511cdde4863f8a7434cef696750681cb9510eea557088f76d9e5065",
}
var element Element
for i, input := range inputs {
hash := sha512.Sum512([]byte(input))
element.FromUniformBytes(hash[:])
if encoding := hex.EncodeToString(element.Encode(nil)); encoding != elements[i] {
t.Errorf("#%d: expected %q, got %q", i, elements[i], encoding)
}
}
}
func TestEquivalentFromUniformBytes(t *testing.T) {
inputs := []string{
"edffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" +
"1200000000000000000000000000000000000000000000000000000000000000",
"edffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f" +
"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
"0000000000000000000000000000000000000000000000000000000000000080" +
"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
"0000000000000000000000000000000000000000000000000000000000000000" +
"1200000000000000000000000000000000000000000000000000000000000080",
}
expected := "304282791023b73128d277bdcb5c7746ef2eac08dde9f2983379cb8e5ef0517f"
var element Element
for i, input := range inputs {
h, err := hex.DecodeString(input)
if err != nil {
t.Fatalf("#%d: bad hex encoding in test vector: %v", i, err)
}
element.FromUniformBytes(h[:])
if encoding := hex.EncodeToString(element.Encode(nil)); encoding != expected {
t.Errorf("#%d: expected %q, got %q", i, expected, encoding)
}
}
}
func TestMarshalScalar(t *testing.T) {
x := new(Scalar)
// generate an arbitrary scalar
xbytes := sha512.Sum512([]byte("Hello World"))
x.SetUniformBytes(xbytes[:])
text, err := json.Marshal(x)
if err != nil {
t.Fatalf("Could not marshal json: %v", err)
}
t.Logf("json: %s", text)
y := new(Scalar)
err = json.Unmarshal(text, y)
if err != nil || y.Equal(x) == 0 {
t.Fatalf("Error unmarshaling scalar from json: %s %v", text, err)
}
}
func TestMarshalElement(t *testing.T) {
x := new(Element)
// generate an arbitrary element
xbytes := sha512.Sum512([]byte("Hello World"))
x.FromUniformBytes(xbytes[:])
text, err := json.Marshal(x)
if err != nil {
t.Fatalf("Could not marshal json: %v", err)
}
t.Logf("json: %s", text)
y := new(Element)
err = json.Unmarshal(text, y)
if err != nil || y.Equal(x) == 0 {
t.Fatalf("Error unmarshaling element from json: %s %v", text, err)
}
}
func TestElementSet(t *testing.T) {
// Test this, because the internal point type being hard-copyable isn't part of the spec.
el1 := NewIdentityElement()
el2 := NewGeneratorElement()
if el1.Equal(el2) == 1 {
t.Error("shouldn't be the same")
}
// Check new value
el1.Set(el2)
if el1.Equal(el2) == 0 {
t.Error("failed to set the value")
}
// Mutate source var
el2.Add(el2, el2)
if el1.Equal(el2) == 1 {
t.Error("shouldn't have changed")
}
}
func TestScalarSet(t *testing.T) {
// Test this, because the internal scalar representation being hard-copyable isn't part of the spec.
// 32-byte little endian value of "1"
scOne := make([]byte, 32)
scOne[0] = 0x01
sc1, sc2 := NewScalar(), NewScalar()
// sc1 <- 1
sc1.SetCanonicalBytes(scOne)
// 1 != 0
if sc1.Equal(sc2) == 1 {
t.Error("shouldn't be the same")
}
// sc2 <- sc1
sc2.Set(sc1)
// 1 == 1
if sc1.Equal(sc2) == 0 {
t.Error("failed to set the value")
}
// sc1 <- 1 + 1
sc1.Add(sc1, sc1)
// 2 != 1
if sc1.Equal(sc2) == 1 {
t.Error("shouldn't have changed")
}
}
func TestConstants(t *testing.T) {
// From draft-hdevalence-cfrg-ristretto-01, Section 3.1.
t.Run("d", func(t *testing.T) {
testConstant(t, d,
"37095705934669439343138083508754565189542113879843219016388785533085940283555")
})
t.Run("sqrtM1", func(t *testing.T) {
testConstant(t, sqrtM1,
"19681161376707505956807079304988542015446066515923890162744021073123829784752")
})
t.Run("sqrtADMinusOne", func(t *testing.T) {
testConstant(t, sqrtADMinusOne,
"25063068953384623474111414158702152701244531502492656460079210482610430750235")
})
t.Run("invSqrtAMinusD", func(t *testing.T) {
testConstant(t, invSqrtAMinusD,
"54469307008909316920995813868745141605393597292927456921205312896311721017578")
})
t.Run("oneMinusDSQ", func(t *testing.T) {
testConstant(t, oneMinusDSQ,
"1159843021668779879193775521855586647937357759715417654439879720876111806838")
})
t.Run("dMinusOneSQ", func(t *testing.T) {
testConstant(t, dMinusOneSQ,
"40440834346308536858101042469323190826248399146238708352240133220865137265952")
})
}
func testConstant(t *testing.T, f *field.Element, decimal string) {
b, ok := new(big.Int).SetString(decimal, 10)
if !ok {
t.Fatal("invalid decimal")
}
buf := b.FillBytes(make([]byte, 32))
for i := 0; i < len(buf)/2; i++ {
buf[i], buf[len(buf)-i-1] = buf[len(buf)-i-1], buf[i]
}
if !bytes.Equal(f.Bytes(), buf) {
t.Errorf("expected %x", buf)
}
}