libgo/go/crypto/elliptic/elliptic_test.go

   1 // Copyright 2010 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package elliptic
   6
   7 import (
   8         "crypto/rand"
   9         "encoding/hex"
  10         "fmt"
  11         "math/big"
  12         "testing"
  13 )
  14
  15 func TestOnCurve(t *testing.T) {
  16         p224 := P224()
  17         if !p224.IsOnCurve(p224.Params().Gx, p224.Params().Gy) {
  18                 t.Errorf("FAIL")
  19         }
  20 }
  21
  22 func TestOffCurve(t *testing.T) {
  23         p224 := P224()
  24         x, y := new(big.Int).SetInt64(1), new(big.Int).SetInt64(1)
  25         if p224.IsOnCurve(x, y) {
  26                 t.Errorf("FAIL: point off curve is claimed to be on the curve")
  27         }
  28         b := Marshal(p224, x, y)
  29         x1, y1 := Unmarshal(p224, b)
  30         if x1 != nil || y1 != nil {
  31                 t.Errorf("FAIL: unmarshaling a point not on the curve succeeded")
  32         }
  33 }
  34
  35 type baseMultTest struct {
  36         k    string
  37         x, y string
  38 }
  39
  40 var p224BaseMultTests = []baseMultTest{
  41         {
  42                 "1",
  43                 "b70e0cbd6bb4bf7f321390b94a03c1d356c21122343280d6115c1d21",
  44                 "bd376388b5f723fb4c22dfe6cd4375a05a07476444d5819985007e34",
  45         },
  46         {
  47                 "2",
  48                 "706a46dc76dcb76798e60e6d89474788d16dc18032d268fd1a704fa6",
  49                 "1c2b76a7bc25e7702a704fa986892849fca629487acf3709d2e4e8bb",
  50         },
  51         {
  52                 "3",
  53                 "df1b1d66a551d0d31eff822558b9d2cc75c2180279fe0d08fd896d04",
  54                 "a3f7f03cadd0be444c0aa56830130ddf77d317344e1af3591981a925",
  55         },
  56         {
  57                 "4",
  58                 "ae99feebb5d26945b54892092a8aee02912930fa41cd114e40447301",
  59                 "482580a0ec5bc47e88bc8c378632cd196cb3fa058a7114eb03054c9",
  60         },
  61         {
  62                 "5",
  63                 "31c49ae75bce7807cdff22055d94ee9021fedbb5ab51c57526f011aa",
  64                 "27e8bff1745635ec5ba0c9f1c2ede15414c6507d29ffe37e790a079b",
  65         },
  66         {
  67                 "6",
  68                 "1f2483f82572251fca975fea40db821df8ad82a3c002ee6c57112408",
  69                 "89faf0ccb750d99b553c574fad7ecfb0438586eb3952af5b4b153c7e",
  70         },
  71         {
  72                 "7",
  73                 "db2f6be630e246a5cf7d99b85194b123d487e2d466b94b24a03c3e28",
  74                 "f3a30085497f2f611ee2517b163ef8c53b715d18bb4e4808d02b963",
  75         },
  76         {
  77                 "8",
  78                 "858e6f9cc6c12c31f5df124aa77767b05c8bc021bd683d2b55571550",
  79                 "46dcd3ea5c43898c5c5fc4fdac7db39c2f02ebee4e3541d1e78047a",
  80         },
  81         {
  82                 "9",
  83                 "2fdcccfee720a77ef6cb3bfbb447f9383117e3daa4a07e36ed15f78d",
  84                 "371732e4f41bf4f7883035e6a79fcedc0e196eb07b48171697517463",
  85         },
  86         {
  87                 "10",
  88                 "aea9e17a306517eb89152aa7096d2c381ec813c51aa880e7bee2c0fd",
  89                 "39bb30eab337e0a521b6cba1abe4b2b3a3e524c14a3fe3eb116b655f",
  90         },
  91         {
  92                 "11",
  93                 "ef53b6294aca431f0f3c22dc82eb9050324f1d88d377e716448e507c",
  94                 "20b510004092e96636cfb7e32efded8265c266dfb754fa6d6491a6da",
  95         },
  96         {
  97                 "12",
  98                 "6e31ee1dc137f81b056752e4deab1443a481033e9b4c93a3044f4f7a",
  99                 "207dddf0385bfdeab6e9acda8da06b3bbef224a93ab1e9e036109d13",
 100         },
 101         {
 102                 "13",
 103                 "34e8e17a430e43289793c383fac9774247b40e9ebd3366981fcfaeca",
 104                 "252819f71c7fb7fbcb159be337d37d3336d7feb963724fdfb0ecb767",
 105         },
 106         {
 107                 "14",
 108                 "a53640c83dc208603ded83e4ecf758f24c357d7cf48088b2ce01e9fa",
 109                 "d5814cd724199c4a5b974a43685fbf5b8bac69459c9469bc8f23ccaf",
 110         },
 111         {
 112                 "15",
 113                 "baa4d8635511a7d288aebeedd12ce529ff102c91f97f867e21916bf9",
 114                 "979a5f4759f80f4fb4ec2e34f5566d595680a11735e7b61046127989",
 115         },
 116         {
 117                 "16",
 118                 "b6ec4fe1777382404ef679997ba8d1cc5cd8e85349259f590c4c66d",
 119                 "3399d464345906b11b00e363ef429221f2ec720d2f665d7dead5b482",
 120         },
 121         {
 122                 "17",
 123                 "b8357c3a6ceef288310e17b8bfeff9200846ca8c1942497c484403bc",
 124                 "ff149efa6606a6bd20ef7d1b06bd92f6904639dce5174db6cc554a26",
 125         },
 126         {
 127                 "18",
 128                 "c9ff61b040874c0568479216824a15eab1a838a797d189746226e4cc",
 129                 "ea98d60e5ffc9b8fcf999fab1df7e7ef7084f20ddb61bb045a6ce002",
 130         },
 131         {
 132                 "19",
 133                 "a1e81c04f30ce201c7c9ace785ed44cc33b455a022f2acdbc6cae83c",
 134                 "dcf1f6c3db09c70acc25391d492fe25b4a180babd6cea356c04719cd",
 135         },
 136         {
 137                 "20",
 138                 "fcc7f2b45df1cd5a3c0c0731ca47a8af75cfb0347e8354eefe782455",
 139                 "d5d7110274cba7cdee90e1a8b0d394c376a5573db6be0bf2747f530",
 140         },
 141         {
 142                 "112233445566778899",
 143                 "61f077c6f62ed802dad7c2f38f5c67f2cc453601e61bd076bb46179e",
 144                 "2272f9e9f5933e70388ee652513443b5e289dd135dcc0d0299b225e4",
 145         },
 146         {
 147                 "112233445566778899112233445566778899",
 148                 "29895f0af496bfc62b6ef8d8a65c88c613949b03668aab4f0429e35",
 149                 "3ea6e53f9a841f2019ec24bde1a75677aa9b5902e61081c01064de93",
 150         },
 151         {
 152                 "6950511619965839450988900688150712778015737983940691968051900319680",
 153                 "ab689930bcae4a4aa5f5cb085e823e8ae30fd365eb1da4aba9cf0379",
 154                 "3345a121bbd233548af0d210654eb40bab788a03666419be6fbd34e7",
 155         },
 156         {
 157                 "13479972933410060327035789020509431695094902435494295338570602119423",
 158                 "bdb6a8817c1f89da1c2f3dd8e97feb4494f2ed302a4ce2bc7f5f4025",
 159                 "4c7020d57c00411889462d77a5438bb4e97d177700bf7243a07f1680",
 160         },
 161         {
 162                 "13479971751745682581351455311314208093898607229429740618390390702079",
 163                 "d58b61aa41c32dd5eba462647dba75c5d67c83606c0af2bd928446a9",
 164                 "d24ba6a837be0460dd107ae77725696d211446c5609b4595976b16bd",
 165         },
 166         {
 167                 "13479972931865328106486971546324465392952975980343228160962702868479",
 168                 "dc9fa77978a005510980e929a1485f63716df695d7a0c18bb518df03",
 169                 "ede2b016f2ddffc2a8c015b134928275ce09e5661b7ab14ce0d1d403",
 170         },
 171         {
 172                 "11795773708834916026404142434151065506931607341523388140225443265536",
 173                 "499d8b2829cfb879c901f7d85d357045edab55028824d0f05ba279ba",
 174                 "bf929537b06e4015919639d94f57838fa33fc3d952598dcdbb44d638",
 175         },
 176         {
 177                 "784254593043826236572847595991346435467177662189391577090",
 178                 "8246c999137186632c5f9eddf3b1b0e1764c5e8bd0e0d8a554b9cb77",
 179                 "e80ed8660bc1cb17ac7d845be40a7a022d3306f116ae9f81fea65947",
 180         },
 181         {
 182                 "13479767645505654746623887797783387853576174193480695826442858012671",
 183                 "6670c20afcceaea672c97f75e2e9dd5c8460e54bb38538ebb4bd30eb",
 184                 "f280d8008d07a4caf54271f993527d46ff3ff46fd1190a3f1faa4f74",
 185         },
 186         {
 187                 "205688069665150753842126177372015544874550518966168735589597183",
 188                 "eca934247425cfd949b795cb5ce1eff401550386e28d1a4c5a8eb",
 189                 "d4c01040dba19628931bc8855370317c722cbd9ca6156985f1c2e9ce",
 190         },
 191         {
 192                 "13479966930919337728895168462090683249159702977113823384618282123295",
 193                 "ef353bf5c73cd551b96d596fbc9a67f16d61dd9fe56af19de1fba9cd",
 194                 "21771b9cdce3e8430c09b3838be70b48c21e15bc09ee1f2d7945b91f",
 195         },
 196         {
 197                 "50210731791415612487756441341851895584393717453129007497216",
 198                 "4036052a3091eb481046ad3289c95d3ac905ca0023de2c03ecd451cf",
 199                 "d768165a38a2b96f812586a9d59d4136035d9c853a5bf2e1c86a4993",
 200         },
 201         {
 202                 "26959946667150639794667015087019625940457807714424391721682722368041",
 203                 "fcc7f2b45df1cd5a3c0c0731ca47a8af75cfb0347e8354eefe782455",
 204                 "f2a28eefd8b345832116f1e574f2c6b2c895aa8c24941f40d8b80ad1",
 205         },
 206         {
 207                 "26959946667150639794667015087019625940457807714424391721682722368042",
 208                 "a1e81c04f30ce201c7c9ace785ed44cc33b455a022f2acdbc6cae83c",
 209                 "230e093c24f638f533dac6e2b6d01da3b5e7f45429315ca93fb8e634",
 210         },
 211         {
 212                 "26959946667150639794667015087019625940457807714424391721682722368043",
 213                 "c9ff61b040874c0568479216824a15eab1a838a797d189746226e4cc",
 214                 "156729f1a003647030666054e208180f8f7b0df2249e44fba5931fff",
 215         },
 216         {
 217                 "26959946667150639794667015087019625940457807714424391721682722368044",
 218                 "b8357c3a6ceef288310e17b8bfeff9200846ca8c1942497c484403bc",
 219                 "eb610599f95942df1082e4f9426d086fb9c6231ae8b24933aab5db",
 220         },
 221         {
 222                 "26959946667150639794667015087019625940457807714424391721682722368045",
 223                 "b6ec4fe1777382404ef679997ba8d1cc5cd8e85349259f590c4c66d",
 224                 "cc662b9bcba6f94ee4ff1c9c10bd6ddd0d138df2d099a282152a4b7f",
 225         },
 226         {
 227                 "26959946667150639794667015087019625940457807714424391721682722368046",
 228                 "baa4d8635511a7d288aebeedd12ce529ff102c91f97f867e21916bf9",
 229                 "6865a0b8a607f0b04b13d1cb0aa992a5a97f5ee8ca1849efb9ed8678",
 230         },
 231         {
 232                 "26959946667150639794667015087019625940457807714424391721682722368047",
 233                 "a53640c83dc208603ded83e4ecf758f24c357d7cf48088b2ce01e9fa",
 234                 "2a7eb328dbe663b5a468b5bc97a040a3745396ba636b964370dc3352",
 235         },
 236         {
 237                 "26959946667150639794667015087019625940457807714424391721682722368048",
 238                 "34e8e17a430e43289793c383fac9774247b40e9ebd3366981fcfaeca",
 239                 "dad7e608e380480434ea641cc82c82cbc92801469c8db0204f13489a",
 240         },
 241         {
 242                 "26959946667150639794667015087019625940457807714424391721682722368049",
 243                 "6e31ee1dc137f81b056752e4deab1443a481033e9b4c93a3044f4f7a",
 244                 "df82220fc7a4021549165325725f94c3410ddb56c54e161fc9ef62ee",
 245         },
 246         {
 247                 "26959946667150639794667015087019625940457807714424391721682722368050",
 248                 "ef53b6294aca431f0f3c22dc82eb9050324f1d88d377e716448e507c",
 249                 "df4aefffbf6d1699c930481cd102127c9a3d992048ab05929b6e5927",
 250         },
 251         {
 252                 "26959946667150639794667015087019625940457807714424391721682722368051",
 253                 "aea9e17a306517eb89152aa7096d2c381ec813c51aa880e7bee2c0fd",
 254                 "c644cf154cc81f5ade49345e541b4d4b5c1adb3eb5c01c14ee949aa2",
 255         },
 256         {
 257                 "26959946667150639794667015087019625940457807714424391721682722368052",
 258                 "2fdcccfee720a77ef6cb3bfbb447f9383117e3daa4a07e36ed15f78d",
 259                 "c8e8cd1b0be40b0877cfca1958603122f1e6914f84b7e8e968ae8b9e",
 260         },
 261         {
 262                 "26959946667150639794667015087019625940457807714424391721682722368053",
 263                 "858e6f9cc6c12c31f5df124aa77767b05c8bc021bd683d2b55571550",
 264                 "fb9232c15a3bc7673a3a03b0253824c53d0fd1411b1cabe2e187fb87",
 265         },
 266         {
 267                 "26959946667150639794667015087019625940457807714424391721682722368054",
 268                 "db2f6be630e246a5cf7d99b85194b123d487e2d466b94b24a03c3e28",
 269                 "f0c5cff7ab680d09ee11dae84e9c1072ac48ea2e744b1b7f72fd469e",
 270         },
 271         {
 272                 "26959946667150639794667015087019625940457807714424391721682722368055",
 273                 "1f2483f82572251fca975fea40db821df8ad82a3c002ee6c57112408",
 274                 "76050f3348af2664aac3a8b05281304ebc7a7914c6ad50a4b4eac383",
 275         },
 276         {
 277                 "26959946667150639794667015087019625940457807714424391721682722368056",
 278                 "31c49ae75bce7807cdff22055d94ee9021fedbb5ab51c57526f011aa",
 279                 "d817400e8ba9ca13a45f360e3d121eaaeb39af82d6001c8186f5f866",
 280         },
 281         {
 282                 "26959946667150639794667015087019625940457807714424391721682722368057",
 283                 "ae99feebb5d26945b54892092a8aee02912930fa41cd114e40447301",
 284                 "fb7da7f5f13a43b81774373c879cd32d6934c05fa758eeb14fcfab38",
 285         },
 286         {
 287                 "26959946667150639794667015087019625940457807714424391721682722368058",
 288                 "df1b1d66a551d0d31eff822558b9d2cc75c2180279fe0d08fd896d04",
 289                 "5c080fc3522f41bbb3f55a97cfecf21f882ce8cbb1e50ca6e67e56dc",
 290         },
 291         {
 292                 "26959946667150639794667015087019625940457807714424391721682722368059",
 293                 "706a46dc76dcb76798e60e6d89474788d16dc18032d268fd1a704fa6",
 294                 "e3d4895843da188fd58fb0567976d7b50359d6b78530c8f62d1b1746",
 295         },
 296         {
 297                 "26959946667150639794667015087019625940457807714424391721682722368060",
 298                 "b70e0cbd6bb4bf7f321390b94a03c1d356c21122343280d6115c1d21",
 299                 "42c89c774a08dc04b3dd201932bc8a5ea5f8b89bbb2a7e667aff81cd",
 300         },
 301 }
 302
 303 type scalarMultTest struct {
 304         k          string
 305         xIn, yIn   string
 306         xOut, yOut string
 307 }
 308
 309 var p256MultTests = []scalarMultTest{
 310         {
 311                 "2a265f8bcbdcaf94d58519141e578124cb40d64a501fba9c11847b28965bc737",
 312                 "023819813ac969847059028ea88a1f30dfbcde03fc791d3a252c6b41211882ea",
 313                 "f93e4ae433cc12cf2a43fc0ef26400c0e125508224cdb649380f25479148a4ad",
 314                 "4d4de80f1534850d261075997e3049321a0864082d24a917863366c0724f5ae3",
 315                 "a22d2b7f7818a3563e0f7a76c9bf0921ac55e06e2e4d11795b233824b1db8cc0",
 316         },
 317         {
 318                 "313f72ff9fe811bf573176231b286a3bdb6f1b14e05c40146590727a71c3bccd",
 319                 "cc11887b2d66cbae8f4d306627192522932146b42f01d3c6f92bd5c8ba739b06",
 320                 "a2f08a029cd06b46183085bae9248b0ed15b70280c7ef13a457f5af382426031",
 321                 "831c3f6b5f762d2f461901577af41354ac5f228c2591f84f8a6e51e2e3f17991",
 322                 "93f90934cd0ef2c698cc471c60a93524e87ab31ca2412252337f364513e43684",
 323         },
 324 }
 325
 326 func TestBaseMult(t *testing.T) {
 327         p224 := P224()
 328         for i, e := range p224BaseMultTests {
 329                 k, ok := new(big.Int).SetString(e.k, 10)
 330                 if !ok {
 331                         t.Errorf("%d: bad value for k: %s", i, e.k)
 332                 }
 333                 x, y := p224.ScalarBaseMult(k.Bytes())
 334                 if fmt.Sprintf("%x", x) != e.x || fmt.Sprintf("%x", y) != e.y {
 335                         t.Errorf("%d: bad output for k=%s: got (%x, %x), want (%s, %s)", i, e.k, x, y, e.x, e.y)
 336                 }
 337                 if testing.Short() && i > 5 {
 338                         break
 339                 }
 340         }
 341 }
 342
 343 func TestGenericBaseMult(t *testing.T) {
 344         // We use the P224 CurveParams directly in order to test the generic implementation.
 345         p224 := P224().Params()
 346         for i, e := range p224BaseMultTests {
 347                 k, ok := new(big.Int).SetString(e.k, 10)
 348                 if !ok {
 349                         t.Errorf("%d: bad value for k: %s", i, e.k)
 350                 }
 351                 x, y := p224.ScalarBaseMult(k.Bytes())
 352                 if fmt.Sprintf("%x", x) != e.x || fmt.Sprintf("%x", y) != e.y {
 353                         t.Errorf("%d: bad output for k=%s: got (%x, %x), want (%s, %s)", i, e.k, x, y, e.x, e.y)
 354                 }
 355                 if testing.Short() && i > 5 {
 356                         break
 357                 }
 358         }
 359 }
 360
 361 func TestP256BaseMult(t *testing.T) {
 362         p256 := P256()
 363         p256Generic := p256.Params()
 364
 365         scalars := make([]*big.Int, 0, len(p224BaseMultTests)+1)
 366         for _, e := range p224BaseMultTests {
 367                 k, _ := new(big.Int).SetString(e.k, 10)
 368                 scalars = append(scalars, k)
 369         }
 370         k := new(big.Int).SetInt64(1)
 371         k.Lsh(k, 500)
 372         scalars = append(scalars, k)
 373
 374         for i, k := range scalars {
 375                 x, y := p256.ScalarBaseMult(k.Bytes())
 376                 x2, y2 := p256Generic.ScalarBaseMult(k.Bytes())
 377                 if x.Cmp(x2) != 0 || y.Cmp(y2) != 0 {
 378                         t.Errorf("#%d: got (%x, %x), want (%x, %x)", i, x, y, x2, y2)
 379                 }
 380
 381                 if testing.Short() && i > 5 {
 382                         break
 383                 }
 384         }
 385 }
 386
 387 func TestP256Mult(t *testing.T) {
 388         p256 := P256()
 389         p256Generic := p256.Params()
 390
 391         for i, e := range p224BaseMultTests {
 392                 x, _ := new(big.Int).SetString(e.x, 16)
 393                 y, _ := new(big.Int).SetString(e.y, 16)
 394                 k, _ := new(big.Int).SetString(e.k, 10)
 395
 396                 xx, yy := p256.ScalarMult(x, y, k.Bytes())
 397                 xx2, yy2 := p256Generic.ScalarMult(x, y, k.Bytes())
 398                 if xx.Cmp(xx2) != 0 || yy.Cmp(yy2) != 0 {
 399                         t.Errorf("#%d: got (%x, %x), want (%x, %x)", i, xx, yy, xx2, yy2)
 400                 }
 401                 if testing.Short() && i > 5 {
 402                         break
 403                 }
 404         }
 405
 406         for i, e := range p256MultTests {
 407                 x, _ := new(big.Int).SetString(e.xIn, 16)
 408                 y, _ := new(big.Int).SetString(e.yIn, 16)
 409                 k, _ := new(big.Int).SetString(e.k, 16)
 410                 expectedX, _ := new(big.Int).SetString(e.xOut, 16)
 411                 expectedY, _ := new(big.Int).SetString(e.yOut, 16)
 412
 413                 xx, yy := p256.ScalarMult(x, y, k.Bytes())
 414                 if xx.Cmp(expectedX) != 0 || yy.Cmp(expectedY) != 0 {
 415                         t.Errorf("#%d: got (%x, %x), want (%x, %x)", i, xx, yy, expectedX, expectedY)
 416                 }
 417         }
 418 }
 419
 420 func TestInfinity(t *testing.T) {
 421         tests := []struct {
 422                 name  string
 423                 curve Curve
 424         }{
 425                 {"p224", P224()},
 426                 {"p256", P256()},
 427         }
 428
 429         for _, test := range tests {
 430                 curve := test.curve
 431                 x, y := curve.ScalarBaseMult(nil)
 432                 if x.Sign() != 0 || y.Sign() != 0 {
 433                         t.Errorf("%s: x^0 != ∞", test.name)
 434                 }
 435                 x.SetInt64(0)
 436                 y.SetInt64(0)
 437
 438                 x2, y2 := curve.Double(x, y)
 439                 if x2.Sign() != 0 || y2.Sign() != 0 {
 440                         t.Errorf("%s: 2∞ != ∞", test.name)
 441                 }
 442
 443                 baseX := curve.Params().Gx
 444                 baseY := curve.Params().Gy
 445
 446                 x3, y3 := curve.Add(baseX, baseY, x, y)
 447                 if x3.Cmp(baseX) != 0 || y3.Cmp(baseY) != 0 {
 448                         t.Errorf("%s: x+∞ != x", test.name)
 449                 }
 450
 451                 x4, y4 := curve.Add(x, y, baseX, baseY)
 452                 if x4.Cmp(baseX) != 0 || y4.Cmp(baseY) != 0 {
 453                         t.Errorf("%s: ∞+x != x", test.name)
 454                 }
 455         }
 456 }
 457
 458 func BenchmarkBaseMult(b *testing.B) {
 459         b.ResetTimer()
 460         p224 := P224()
 461         e := p224BaseMultTests[25]
 462         k, _ := new(big.Int).SetString(e.k, 10)
 463         b.StartTimer()
 464         for i := 0; i < b.N; i++ {
 465                 p224.ScalarBaseMult(k.Bytes())
 466         }
 467 }
 468
 469 func BenchmarkBaseMultP256(b *testing.B) {
 470         b.ResetTimer()
 471         p256 := P256()
 472         e := p224BaseMultTests[25]
 473         k, _ := new(big.Int).SetString(e.k, 10)
 474         b.StartTimer()
 475         for i := 0; i < b.N; i++ {
 476                 p256.ScalarBaseMult(k.Bytes())
 477         }
 478 }
 479
 480 func BenchmarkScalarMultP256(b *testing.B) {
 481         b.ResetTimer()
 482         p256 := P256()
 483         _, x, y, _ := GenerateKey(p256, rand.Reader)
 484         priv, _, _, _ := GenerateKey(p256, rand.Reader)
 485
 486         b.StartTimer()
 487         for i := 0; i < b.N; i++ {
 488                 p256.ScalarMult(x, y, priv)
 489         }
 490 }
 491
 492 func TestMarshal(t *testing.T) {
 493         p224 := P224()
 494         _, x, y, err := GenerateKey(p224, rand.Reader)
 495         if err != nil {
 496                 t.Error(err)
 497                 return
 498         }
 499         serialized := Marshal(p224, x, y)
 500         xx, yy := Unmarshal(p224, serialized)
 501         if xx == nil {
 502                 t.Error("failed to unmarshal")
 503                 return
 504         }
 505         if xx.Cmp(x) != 0 || yy.Cmp(y) != 0 {
 506                 t.Error("unmarshal returned different values")
 507                 return
 508         }
 509 }
 510
 511 func TestP224Overflow(t *testing.T) {
 512         // This tests for a specific bug in the P224 implementation.
 513         p224 := P224()
 514         pointData, _ := hex.DecodeString("049B535B45FB0A2072398A6831834624C7E32CCFD5A4B933BCEAF77F1DD945E08BBE5178F5EDF5E733388F196D2A631D2E075BB16CBFEEA15B")
 515         x, y := Unmarshal(p224, pointData)
 516         if !p224.IsOnCurve(x, y) {
 517                 t.Error("P224 failed to validate a correct point")
 518         }
 519 }