ed448.js 19 KB

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  1. /*! noble-curves - MIT License (c) 2022 Paul Miller (paulmillr.com) */
  2. import { shake256 } from '@noble/hashes/sha3';
  3. import { concatBytes, randomBytes, utf8ToBytes, wrapConstructor } from '@noble/hashes/utils';
  4. import { twistedEdwards } from './abstract/edwards.js';
  5. import { createHasher, expand_message_xof } from './abstract/hash-to-curve.js';
  6. import { Field, isNegativeLE, mod, pow2 } from './abstract/modular.js';
  7. import { montgomery } from './abstract/montgomery.js';
  8. import { bytesToHex, bytesToNumberLE, ensureBytes, equalBytes, numberToBytesLE, } from './abstract/utils.js';
  9. /**
  10. * Edwards448 (not Ed448-Goldilocks) curve with following addons:
  11. * - X448 ECDH
  12. * - Decaf cofactor elimination
  13. * - Elligator hash-to-group / point indistinguishability
  14. * Conforms to RFC 8032 https://www.rfc-editor.org/rfc/rfc8032.html#section-5.2
  15. */
  16. const shake256_114 = wrapConstructor(() => shake256.create({ dkLen: 114 }));
  17. const shake256_64 = wrapConstructor(() => shake256.create({ dkLen: 64 }));
  18. const ed448P = BigInt('726838724295606890549323807888004534353641360687318060281490199180612328166730772686396383698676545930088884461843637361053498018365439');
  19. // prettier-ignore
  20. const _1n = BigInt(1), _2n = BigInt(2), _3n = BigInt(3), _4n = BigInt(4), _11n = BigInt(11);
  21. // prettier-ignore
  22. const _22n = BigInt(22), _44n = BigInt(44), _88n = BigInt(88), _223n = BigInt(223);
  23. // powPminus3div4 calculates z = x^k mod p, where k = (p-3)/4.
  24. // Used for efficient square root calculation.
  25. // ((P-3)/4).toString(2) would produce bits [223x 1, 0, 222x 1]
  26. function ed448_pow_Pminus3div4(x) {
  27. const P = ed448P;
  28. const b2 = (x * x * x) % P;
  29. const b3 = (b2 * b2 * x) % P;
  30. const b6 = (pow2(b3, _3n, P) * b3) % P;
  31. const b9 = (pow2(b6, _3n, P) * b3) % P;
  32. const b11 = (pow2(b9, _2n, P) * b2) % P;
  33. const b22 = (pow2(b11, _11n, P) * b11) % P;
  34. const b44 = (pow2(b22, _22n, P) * b22) % P;
  35. const b88 = (pow2(b44, _44n, P) * b44) % P;
  36. const b176 = (pow2(b88, _88n, P) * b88) % P;
  37. const b220 = (pow2(b176, _44n, P) * b44) % P;
  38. const b222 = (pow2(b220, _2n, P) * b2) % P;
  39. const b223 = (pow2(b222, _1n, P) * x) % P;
  40. return (pow2(b223, _223n, P) * b222) % P;
  41. }
  42. function adjustScalarBytes(bytes) {
  43. // Section 5: Likewise, for X448, set the two least significant bits of the first byte to 0, and the most
  44. // significant bit of the last byte to 1.
  45. bytes[0] &= 252; // 0b11111100
  46. // and the most significant bit of the last byte to 1.
  47. bytes[55] |= 128; // 0b10000000
  48. // NOTE: is is NOOP for 56 bytes scalars (X25519/X448)
  49. bytes[56] = 0; // Byte outside of group (456 buts vs 448 bits)
  50. return bytes;
  51. }
  52. // Constant-time ratio of u to v. Allows to combine inversion and square root u/√v.
  53. // Uses algo from RFC8032 5.1.3.
  54. function uvRatio(u, v) {
  55. const P = ed448P;
  56. // https://www.rfc-editor.org/rfc/rfc8032#section-5.2.3
  57. // To compute the square root of (u/v), the first step is to compute the
  58. // candidate root x = (u/v)^((p+1)/4). This can be done using the
  59. // following trick, to use a single modular powering for both the
  60. // inversion of v and the square root:
  61. // x = (u/v)^((p+1)/4) = u³v(u⁵v³)^((p-3)/4) (mod p)
  62. const u2v = mod(u * u * v, P); // u²v
  63. const u3v = mod(u2v * u, P); // u³v
  64. const u5v3 = mod(u3v * u2v * v, P); // u⁵v³
  65. const root = ed448_pow_Pminus3div4(u5v3);
  66. const x = mod(u3v * root, P);
  67. // Verify that root is exists
  68. const x2 = mod(x * x, P); // x²
  69. // If vx² = u, the recovered x-coordinate is x. Otherwise, no
  70. // square root exists, and the decoding fails.
  71. return { isValid: mod(x2 * v, P) === u, value: x };
  72. }
  73. const Fp = Field(ed448P, 456, true);
  74. const ED448_DEF = {
  75. // Param: a
  76. a: BigInt(1),
  77. // -39081. Negative number is P - number
  78. d: BigInt('726838724295606890549323807888004534353641360687318060281490199180612328166730772686396383698676545930088884461843637361053498018326358'),
  79. // Finite field 𝔽p over which we'll do calculations; 2n**448n - 2n**224n - 1n
  80. Fp,
  81. // Subgroup order: how many points curve has;
  82. // 2n**446n - 13818066809895115352007386748515426880336692474882178609894547503885n
  83. n: BigInt('181709681073901722637330951972001133588410340171829515070372549795146003961539585716195755291692375963310293709091662304773755859649779'),
  84. // RFC 7748 has 56-byte keys, RFC 8032 has 57-byte keys
  85. nBitLength: 456,
  86. // Cofactor
  87. h: BigInt(4),
  88. // Base point (x, y) aka generator point
  89. Gx: BigInt('224580040295924300187604334099896036246789641632564134246125461686950415467406032909029192869357953282578032075146446173674602635247710'),
  90. Gy: BigInt('298819210078481492676017930443930673437544040154080242095928241372331506189835876003536878655418784733982303233503462500531545062832660'),
  91. // SHAKE256(dom4(phflag,context)||x, 114)
  92. hash: shake256_114,
  93. randomBytes,
  94. adjustScalarBytes,
  95. // dom4
  96. domain: (data, ctx, phflag) => {
  97. if (ctx.length > 255)
  98. throw new Error(`Context is too big: ${ctx.length}`);
  99. return concatBytes(utf8ToBytes('SigEd448'), new Uint8Array([phflag ? 1 : 0, ctx.length]), ctx, data);
  100. },
  101. uvRatio,
  102. };
  103. export const ed448 = /* @__PURE__ */ twistedEdwards(ED448_DEF);
  104. // NOTE: there is no ed448ctx, since ed448 supports ctx by default
  105. export const ed448ph = /* @__PURE__ */ twistedEdwards({ ...ED448_DEF, prehash: shake256_64 });
  106. export const x448 = /* @__PURE__ */ (() => montgomery({
  107. a: BigInt(156326),
  108. // RFC 7748 has 56-byte keys, RFC 8032 has 57-byte keys
  109. montgomeryBits: 448,
  110. nByteLength: 56,
  111. P: ed448P,
  112. Gu: BigInt(5),
  113. powPminus2: (x) => {
  114. const P = ed448P;
  115. const Pminus3div4 = ed448_pow_Pminus3div4(x);
  116. const Pminus3 = pow2(Pminus3div4, BigInt(2), P);
  117. return mod(Pminus3 * x, P); // Pminus3 * x = Pminus2
  118. },
  119. adjustScalarBytes,
  120. randomBytes,
  121. }))();
  122. /**
  123. * Converts edwards448 public key to x448 public key. Uses formula:
  124. * * `(u, v) = ((y-1)/(y+1), sqrt(156324)*u/x)`
  125. * * `(x, y) = (sqrt(156324)*u/v, (1+u)/(1-u))`
  126. * @example
  127. * const aPub = ed448.getPublicKey(utils.randomPrivateKey());
  128. * x448.getSharedSecret(edwardsToMontgomery(aPub), edwardsToMontgomery(someonesPub))
  129. */
  130. export function edwardsToMontgomeryPub(edwardsPub) {
  131. const { y } = ed448.ExtendedPoint.fromHex(edwardsPub);
  132. const _1n = BigInt(1);
  133. return Fp.toBytes(Fp.create((y - _1n) * Fp.inv(y + _1n)));
  134. }
  135. export const edwardsToMontgomery = edwardsToMontgomeryPub; // deprecated
  136. // TODO: add edwardsToMontgomeryPriv, similar to ed25519 version
  137. // Hash To Curve Elligator2 Map
  138. const ELL2_C1 = (Fp.ORDER - BigInt(3)) / BigInt(4); // 1. c1 = (q - 3) / 4 # Integer arithmetic
  139. const ELL2_J = BigInt(156326);
  140. function map_to_curve_elligator2_curve448(u) {
  141. let tv1 = Fp.sqr(u); // 1. tv1 = u^2
  142. let e1 = Fp.eql(tv1, Fp.ONE); // 2. e1 = tv1 == 1
  143. tv1 = Fp.cmov(tv1, Fp.ZERO, e1); // 3. tv1 = CMOV(tv1, 0, e1) # If Z * u^2 == -1, set tv1 = 0
  144. let xd = Fp.sub(Fp.ONE, tv1); // 4. xd = 1 - tv1
  145. let x1n = Fp.neg(ELL2_J); // 5. x1n = -J
  146. let tv2 = Fp.sqr(xd); // 6. tv2 = xd^2
  147. let gxd = Fp.mul(tv2, xd); // 7. gxd = tv2 * xd # gxd = xd^3
  148. let gx1 = Fp.mul(tv1, Fp.neg(ELL2_J)); // 8. gx1 = -J * tv1 # x1n + J * xd
  149. gx1 = Fp.mul(gx1, x1n); // 9. gx1 = gx1 * x1n # x1n^2 + J * x1n * xd
  150. gx1 = Fp.add(gx1, tv2); // 10. gx1 = gx1 + tv2 # x1n^2 + J * x1n * xd + xd^2
  151. gx1 = Fp.mul(gx1, x1n); // 11. gx1 = gx1 * x1n # x1n^3 + J * x1n^2 * xd + x1n * xd^2
  152. let tv3 = Fp.sqr(gxd); // 12. tv3 = gxd^2
  153. tv2 = Fp.mul(gx1, gxd); // 13. tv2 = gx1 * gxd # gx1 * gxd
  154. tv3 = Fp.mul(tv3, tv2); // 14. tv3 = tv3 * tv2 # gx1 * gxd^3
  155. let y1 = Fp.pow(tv3, ELL2_C1); // 15. y1 = tv3^c1 # (gx1 * gxd^3)^((p - 3) / 4)
  156. y1 = Fp.mul(y1, tv2); // 16. y1 = y1 * tv2 # gx1 * gxd * (gx1 * gxd^3)^((p - 3) / 4)
  157. let x2n = Fp.mul(x1n, Fp.neg(tv1)); // 17. x2n = -tv1 * x1n # x2 = x2n / xd = -1 * u^2 * x1n / xd
  158. let y2 = Fp.mul(y1, u); // 18. y2 = y1 * u
  159. y2 = Fp.cmov(y2, Fp.ZERO, e1); // 19. y2 = CMOV(y2, 0, e1)
  160. tv2 = Fp.sqr(y1); // 20. tv2 = y1^2
  161. tv2 = Fp.mul(tv2, gxd); // 21. tv2 = tv2 * gxd
  162. let e2 = Fp.eql(tv2, gx1); // 22. e2 = tv2 == gx1
  163. let xn = Fp.cmov(x2n, x1n, e2); // 23. xn = CMOV(x2n, x1n, e2) # If e2, x = x1, else x = x2
  164. let y = Fp.cmov(y2, y1, e2); // 24. y = CMOV(y2, y1, e2) # If e2, y = y1, else y = y2
  165. let e3 = Fp.isOdd(y); // 25. e3 = sgn0(y) == 1 # Fix sign of y
  166. y = Fp.cmov(y, Fp.neg(y), e2 !== e3); // 26. y = CMOV(y, -y, e2 XOR e3)
  167. return { xn, xd, yn: y, yd: Fp.ONE }; // 27. return (xn, xd, y, 1)
  168. }
  169. function map_to_curve_elligator2_edwards448(u) {
  170. let { xn, xd, yn, yd } = map_to_curve_elligator2_curve448(u); // 1. (xn, xd, yn, yd) = map_to_curve_elligator2_curve448(u)
  171. let xn2 = Fp.sqr(xn); // 2. xn2 = xn^2
  172. let xd2 = Fp.sqr(xd); // 3. xd2 = xd^2
  173. let xd4 = Fp.sqr(xd2); // 4. xd4 = xd2^2
  174. let yn2 = Fp.sqr(yn); // 5. yn2 = yn^2
  175. let yd2 = Fp.sqr(yd); // 6. yd2 = yd^2
  176. let xEn = Fp.sub(xn2, xd2); // 7. xEn = xn2 - xd2
  177. let tv2 = Fp.sub(xEn, xd2); // 8. tv2 = xEn - xd2
  178. xEn = Fp.mul(xEn, xd2); // 9. xEn = xEn * xd2
  179. xEn = Fp.mul(xEn, yd); // 10. xEn = xEn * yd
  180. xEn = Fp.mul(xEn, yn); // 11. xEn = xEn * yn
  181. xEn = Fp.mul(xEn, _4n); // 12. xEn = xEn * 4
  182. tv2 = Fp.mul(tv2, xn2); // 13. tv2 = tv2 * xn2
  183. tv2 = Fp.mul(tv2, yd2); // 14. tv2 = tv2 * yd2
  184. let tv3 = Fp.mul(yn2, _4n); // 15. tv3 = 4 * yn2
  185. let tv1 = Fp.add(tv3, yd2); // 16. tv1 = tv3 + yd2
  186. tv1 = Fp.mul(tv1, xd4); // 17. tv1 = tv1 * xd4
  187. let xEd = Fp.add(tv1, tv2); // 18. xEd = tv1 + tv2
  188. tv2 = Fp.mul(tv2, xn); // 19. tv2 = tv2 * xn
  189. let tv4 = Fp.mul(xn, xd4); // 20. tv4 = xn * xd4
  190. let yEn = Fp.sub(tv3, yd2); // 21. yEn = tv3 - yd2
  191. yEn = Fp.mul(yEn, tv4); // 22. yEn = yEn * tv4
  192. yEn = Fp.sub(yEn, tv2); // 23. yEn = yEn - tv2
  193. tv1 = Fp.add(xn2, xd2); // 24. tv1 = xn2 + xd2
  194. tv1 = Fp.mul(tv1, xd2); // 25. tv1 = tv1 * xd2
  195. tv1 = Fp.mul(tv1, xd); // 26. tv1 = tv1 * xd
  196. tv1 = Fp.mul(tv1, yn2); // 27. tv1 = tv1 * yn2
  197. tv1 = Fp.mul(tv1, BigInt(-2)); // 28. tv1 = -2 * tv1
  198. let yEd = Fp.add(tv2, tv1); // 29. yEd = tv2 + tv1
  199. tv4 = Fp.mul(tv4, yd2); // 30. tv4 = tv4 * yd2
  200. yEd = Fp.add(yEd, tv4); // 31. yEd = yEd + tv4
  201. tv1 = Fp.mul(xEd, yEd); // 32. tv1 = xEd * yEd
  202. let e = Fp.eql(tv1, Fp.ZERO); // 33. e = tv1 == 0
  203. xEn = Fp.cmov(xEn, Fp.ZERO, e); // 34. xEn = CMOV(xEn, 0, e)
  204. xEd = Fp.cmov(xEd, Fp.ONE, e); // 35. xEd = CMOV(xEd, 1, e)
  205. yEn = Fp.cmov(yEn, Fp.ONE, e); // 36. yEn = CMOV(yEn, 1, e)
  206. yEd = Fp.cmov(yEd, Fp.ONE, e); // 37. yEd = CMOV(yEd, 1, e)
  207. const inv = Fp.invertBatch([xEd, yEd]); // batch division
  208. return { x: Fp.mul(xEn, inv[0]), y: Fp.mul(yEn, inv[1]) }; // 38. return (xEn, xEd, yEn, yEd)
  209. }
  210. const htf = /* @__PURE__ */ (() => createHasher(ed448.ExtendedPoint, (scalars) => map_to_curve_elligator2_edwards448(scalars[0]), {
  211. DST: 'edwards448_XOF:SHAKE256_ELL2_RO_',
  212. encodeDST: 'edwards448_XOF:SHAKE256_ELL2_NU_',
  213. p: Fp.ORDER,
  214. m: 1,
  215. k: 224,
  216. expand: 'xof',
  217. hash: shake256,
  218. }))();
  219. export const hashToCurve = /* @__PURE__ */ (() => htf.hashToCurve)();
  220. export const encodeToCurve = /* @__PURE__ */ (() => htf.encodeToCurve)();
  221. function assertDcfPoint(other) {
  222. if (!(other instanceof DcfPoint))
  223. throw new Error('DecafPoint expected');
  224. }
  225. // 1-d
  226. const ONE_MINUS_D = BigInt('39082');
  227. // 1-2d
  228. const ONE_MINUS_TWO_D = BigInt('78163');
  229. // √(-d)
  230. const SQRT_MINUS_D = BigInt('98944233647732219769177004876929019128417576295529901074099889598043702116001257856802131563896515373927712232092845883226922417596214');
  231. // 1 / √(-d)
  232. const INVSQRT_MINUS_D = BigInt('315019913931389607337177038330951043522456072897266928557328499619017160722351061360252776265186336876723201881398623946864393857820716');
  233. // Calculates 1/√(number)
  234. const invertSqrt = (number) => uvRatio(_1n, number);
  235. const MAX_448B = BigInt('0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff');
  236. const bytes448ToNumberLE = (bytes) => ed448.CURVE.Fp.create(bytesToNumberLE(bytes) & MAX_448B);
  237. // Computes Elligator map for Decaf
  238. // https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448-07#name-element-derivation-2
  239. function calcElligatorDecafMap(r0) {
  240. const { d } = ed448.CURVE;
  241. const P = ed448.CURVE.Fp.ORDER;
  242. const mod = ed448.CURVE.Fp.create;
  243. const r = mod(-(r0 * r0)); // 1
  244. const u0 = mod(d * (r - _1n)); // 2
  245. const u1 = mod((u0 + _1n) * (u0 - r)); // 3
  246. const { isValid: was_square, value: v } = uvRatio(ONE_MINUS_TWO_D, mod((r + _1n) * u1)); // 4
  247. let v_prime = v; // 5
  248. if (!was_square)
  249. v_prime = mod(r0 * v);
  250. let sgn = _1n; // 6
  251. if (!was_square)
  252. sgn = mod(-_1n);
  253. const s = mod(v_prime * (r + _1n)); // 7
  254. let s_abs = s;
  255. if (isNegativeLE(s, P))
  256. s_abs = mod(-s);
  257. const s2 = s * s;
  258. const W0 = mod(s_abs * _2n); // 8
  259. const W1 = mod(s2 + _1n); // 9
  260. const W2 = mod(s2 - _1n); // 10
  261. const W3 = mod(v_prime * s * (r - _1n) * ONE_MINUS_TWO_D + sgn); // 11
  262. return new ed448.ExtendedPoint(mod(W0 * W3), mod(W2 * W1), mod(W1 * W3), mod(W0 * W2));
  263. }
  264. /**
  265. * Each ed448/ExtendedPoint has 4 different equivalent points. This can be
  266. * a source of bugs for protocols like ring signatures. Decaf was created to solve this.
  267. * Decaf point operates in X:Y:Z:T extended coordinates like ExtendedPoint,
  268. * but it should work in its own namespace: do not combine those two.
  269. * https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448
  270. */
  271. class DcfPoint {
  272. // Private property to discourage combining ExtendedPoint + DecafPoint
  273. // Always use Decaf encoding/decoding instead.
  274. constructor(ep) {
  275. this.ep = ep;
  276. }
  277. static fromAffine(ap) {
  278. return new DcfPoint(ed448.ExtendedPoint.fromAffine(ap));
  279. }
  280. /**
  281. * Takes uniform output of 112-byte hash function like shake256 and converts it to `DecafPoint`.
  282. * The hash-to-group operation applies Elligator twice and adds the results.
  283. * **Note:** this is one-way map, there is no conversion from point to hash.
  284. * https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448-07#name-element-derivation-2
  285. * @param hex 112-byte output of a hash function
  286. */
  287. static hashToCurve(hex) {
  288. hex = ensureBytes('decafHash', hex, 112);
  289. const r1 = bytes448ToNumberLE(hex.slice(0, 56));
  290. const R1 = calcElligatorDecafMap(r1);
  291. const r2 = bytes448ToNumberLE(hex.slice(56, 112));
  292. const R2 = calcElligatorDecafMap(r2);
  293. return new DcfPoint(R1.add(R2));
  294. }
  295. /**
  296. * Converts decaf-encoded string to decaf point.
  297. * https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448-07#name-decode-2
  298. * @param hex Decaf-encoded 56 bytes. Not every 56-byte string is valid decaf encoding
  299. */
  300. static fromHex(hex) {
  301. hex = ensureBytes('decafHex', hex, 56);
  302. const { d } = ed448.CURVE;
  303. const P = ed448.CURVE.Fp.ORDER;
  304. const mod = ed448.CURVE.Fp.create;
  305. const emsg = 'DecafPoint.fromHex: the hex is not valid encoding of DecafPoint';
  306. const s = bytes448ToNumberLE(hex);
  307. // 1. Check that s_bytes is the canonical encoding of a field element, or else abort.
  308. // 2. Check that s is non-negative, or else abort
  309. if (!equalBytes(numberToBytesLE(s, 56), hex) || isNegativeLE(s, P))
  310. throw new Error(emsg);
  311. const s2 = mod(s * s); // 1
  312. const u1 = mod(_1n + s2); // 2
  313. const u1sq = mod(u1 * u1);
  314. const u2 = mod(u1sq - _4n * d * s2); // 3
  315. const { isValid, value: invsqrt } = invertSqrt(mod(u2 * u1sq)); // 4
  316. let u3 = mod((s + s) * invsqrt * u1 * SQRT_MINUS_D); // 5
  317. if (isNegativeLE(u3, P))
  318. u3 = mod(-u3);
  319. const x = mod(u3 * invsqrt * u2 * INVSQRT_MINUS_D); // 6
  320. const y = mod((_1n - s2) * invsqrt * u1); // 7
  321. const t = mod(x * y); // 8
  322. if (!isValid)
  323. throw new Error(emsg);
  324. return new DcfPoint(new ed448.ExtendedPoint(x, y, _1n, t));
  325. }
  326. /**
  327. * Encodes decaf point to Uint8Array.
  328. * https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448-07#name-encode-2
  329. */
  330. toRawBytes() {
  331. let { ex: x, ey: _y, ez: z, et: t } = this.ep;
  332. const P = ed448.CURVE.Fp.ORDER;
  333. const mod = ed448.CURVE.Fp.create;
  334. const u1 = mod(mod(x + t) * mod(x - t)); // 1
  335. const x2 = mod(x * x);
  336. const { value: invsqrt } = invertSqrt(mod(u1 * ONE_MINUS_D * x2)); // 2
  337. let ratio = mod(invsqrt * u1 * SQRT_MINUS_D); // 3
  338. if (isNegativeLE(ratio, P))
  339. ratio = mod(-ratio);
  340. const u2 = mod(INVSQRT_MINUS_D * ratio * z - t); // 4
  341. let s = mod(ONE_MINUS_D * invsqrt * x * u2); // 5
  342. if (isNegativeLE(s, P))
  343. s = mod(-s);
  344. return numberToBytesLE(s, 56);
  345. }
  346. toHex() {
  347. return bytesToHex(this.toRawBytes());
  348. }
  349. toString() {
  350. return this.toHex();
  351. }
  352. // Compare one point to another.
  353. // https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448-07#name-equals-2
  354. equals(other) {
  355. assertDcfPoint(other);
  356. const { ex: X1, ey: Y1 } = this.ep;
  357. const { ex: X2, ey: Y2 } = other.ep;
  358. const mod = ed448.CURVE.Fp.create;
  359. // (x1 * y2 == y1 * x2)
  360. return mod(X1 * Y2) === mod(Y1 * X2);
  361. }
  362. add(other) {
  363. assertDcfPoint(other);
  364. return new DcfPoint(this.ep.add(other.ep));
  365. }
  366. subtract(other) {
  367. assertDcfPoint(other);
  368. return new DcfPoint(this.ep.subtract(other.ep));
  369. }
  370. multiply(scalar) {
  371. return new DcfPoint(this.ep.multiply(scalar));
  372. }
  373. multiplyUnsafe(scalar) {
  374. return new DcfPoint(this.ep.multiplyUnsafe(scalar));
  375. }
  376. double() {
  377. return new DcfPoint(this.ep.double());
  378. }
  379. negate() {
  380. return new DcfPoint(this.ep.negate());
  381. }
  382. }
  383. export const DecafPoint = /* @__PURE__ */ (() => {
  384. // decaf448 base point is ed448 base x 2
  385. // https://github.com/dalek-cryptography/curve25519-dalek/blob/59837c6ecff02b77b9d5ff84dbc239d0cf33ef90/vendor/ristretto.sage#L699
  386. if (!DcfPoint.BASE)
  387. DcfPoint.BASE = new DcfPoint(ed448.ExtendedPoint.BASE).multiply(_2n);
  388. if (!DcfPoint.ZERO)
  389. DcfPoint.ZERO = new DcfPoint(ed448.ExtendedPoint.ZERO);
  390. return DcfPoint;
  391. })();
  392. // Hashing to decaf448. https://www.rfc-editor.org/rfc/rfc9380#appendix-C
  393. export const hashToDecaf448 = (msg, options) => {
  394. const d = options.DST;
  395. const DST = typeof d === 'string' ? utf8ToBytes(d) : d;
  396. const uniform_bytes = expand_message_xof(msg, DST, 112, 224, shake256);
  397. const P = DcfPoint.hashToCurve(uniform_bytes);
  398. return P;
  399. };
  400. export const hash_to_decaf448 = hashToDecaf448; // legacy
  401. //# sourceMappingURL=ed448.js.map