ed25519.js 20 KB

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  1. /*! noble-curves - MIT License (c) 2022 Paul Miller (paulmillr.com) */
  2. import { sha512 } from '@noble/hashes/sha512';
  3. import { concatBytes, randomBytes, utf8ToBytes } from '@noble/hashes/utils';
  4. import { twistedEdwards } from './abstract/edwards.js';
  5. import { createHasher, expand_message_xmd } from './abstract/hash-to-curve.js';
  6. import { Field, FpSqrtEven, 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. * ed25519 Twisted Edwards curve with following addons:
  11. * - X25519 ECDH
  12. * - Ristretto cofactor elimination
  13. * - Elligator hash-to-group / point indistinguishability
  14. */
  15. const ED25519_P = BigInt('57896044618658097711785492504343953926634992332820282019728792003956564819949');
  16. // √(-1) aka √(a) aka 2^((p-1)/4)
  17. const ED25519_SQRT_M1 = /* @__PURE__ */ BigInt('19681161376707505956807079304988542015446066515923890162744021073123829784752');
  18. // prettier-ignore
  19. const _0n = BigInt(0), _1n = BigInt(1), _2n = BigInt(2), _3n = BigInt(3);
  20. // prettier-ignore
  21. const _5n = BigInt(5), _8n = BigInt(8);
  22. function ed25519_pow_2_252_3(x) {
  23. // prettier-ignore
  24. const _10n = BigInt(10), _20n = BigInt(20), _40n = BigInt(40), _80n = BigInt(80);
  25. const P = ED25519_P;
  26. const x2 = (x * x) % P;
  27. const b2 = (x2 * x) % P; // x^3, 11
  28. const b4 = (pow2(b2, _2n, P) * b2) % P; // x^15, 1111
  29. const b5 = (pow2(b4, _1n, P) * x) % P; // x^31
  30. const b10 = (pow2(b5, _5n, P) * b5) % P;
  31. const b20 = (pow2(b10, _10n, P) * b10) % P;
  32. const b40 = (pow2(b20, _20n, P) * b20) % P;
  33. const b80 = (pow2(b40, _40n, P) * b40) % P;
  34. const b160 = (pow2(b80, _80n, P) * b80) % P;
  35. const b240 = (pow2(b160, _80n, P) * b80) % P;
  36. const b250 = (pow2(b240, _10n, P) * b10) % P;
  37. const pow_p_5_8 = (pow2(b250, _2n, P) * x) % P;
  38. // ^ To pow to (p+3)/8, multiply it by x.
  39. return { pow_p_5_8, b2 };
  40. }
  41. function adjustScalarBytes(bytes) {
  42. // Section 5: For X25519, in order to decode 32 random bytes as an integer scalar,
  43. // set the three least significant bits of the first byte
  44. bytes[0] &= 248; // 0b1111_1000
  45. // and the most significant bit of the last to zero,
  46. bytes[31] &= 127; // 0b0111_1111
  47. // set the second most significant bit of the last byte to 1
  48. bytes[31] |= 64; // 0b0100_0000
  49. return bytes;
  50. }
  51. // sqrt(u/v)
  52. function uvRatio(u, v) {
  53. const P = ED25519_P;
  54. const v3 = mod(v * v * v, P); // v³
  55. const v7 = mod(v3 * v3 * v, P); // v⁷
  56. // (p+3)/8 and (p-5)/8
  57. const pow = ed25519_pow_2_252_3(u * v7).pow_p_5_8;
  58. let x = mod(u * v3 * pow, P); // (uv³)(uv⁷)^(p-5)/8
  59. const vx2 = mod(v * x * x, P); // vx²
  60. const root1 = x; // First root candidate
  61. const root2 = mod(x * ED25519_SQRT_M1, P); // Second root candidate
  62. const useRoot1 = vx2 === u; // If vx² = u (mod p), x is a square root
  63. const useRoot2 = vx2 === mod(-u, P); // If vx² = -u, set x <-- x * 2^((p-1)/4)
  64. const noRoot = vx2 === mod(-u * ED25519_SQRT_M1, P); // There is no valid root, vx² = -u√(-1)
  65. if (useRoot1)
  66. x = root1;
  67. if (useRoot2 || noRoot)
  68. x = root2; // We return root2 anyway, for const-time
  69. if (isNegativeLE(x, P))
  70. x = mod(-x, P);
  71. return { isValid: useRoot1 || useRoot2, value: x };
  72. }
  73. // Just in case
  74. export const ED25519_TORSION_SUBGROUP = [
  75. '0100000000000000000000000000000000000000000000000000000000000000',
  76. 'c7176a703d4dd84fba3c0b760d10670f2a2053fa2c39ccc64ec7fd7792ac037a',
  77. '0000000000000000000000000000000000000000000000000000000000000080',
  78. '26e8958fc2b227b045c3f489f2ef98f0d5dfac05d3c63339b13802886d53fc05',
  79. 'ecffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f',
  80. '26e8958fc2b227b045c3f489f2ef98f0d5dfac05d3c63339b13802886d53fc85',
  81. '0000000000000000000000000000000000000000000000000000000000000000',
  82. 'c7176a703d4dd84fba3c0b760d10670f2a2053fa2c39ccc64ec7fd7792ac03fa',
  83. ];
  84. const Fp = /* @__PURE__ */ (() => Field(ED25519_P, undefined, true))();
  85. const ed25519Defaults = /* @__PURE__ */ (() => ({
  86. // Param: a
  87. a: BigInt(-1), // Fp.create(-1) is proper; our way still works and is faster
  88. // d is equal to -121665/121666 over finite field.
  89. // Negative number is P - number, and division is invert(number, P)
  90. d: BigInt('37095705934669439343138083508754565189542113879843219016388785533085940283555'),
  91. // Finite field 𝔽p over which we'll do calculations; 2n**255n - 19n
  92. Fp,
  93. // Subgroup order: how many points curve has
  94. // 2n**252n + 27742317777372353535851937790883648493n;
  95. n: BigInt('7237005577332262213973186563042994240857116359379907606001950938285454250989'),
  96. // Cofactor
  97. h: _8n,
  98. // Base point (x, y) aka generator point
  99. Gx: BigInt('15112221349535400772501151409588531511454012693041857206046113283949847762202'),
  100. Gy: BigInt('46316835694926478169428394003475163141307993866256225615783033603165251855960'),
  101. hash: sha512,
  102. randomBytes,
  103. adjustScalarBytes,
  104. // dom2
  105. // Ratio of u to v. Allows us to combine inversion and square root. Uses algo from RFC8032 5.1.3.
  106. // Constant-time, u/√v
  107. uvRatio,
  108. }))();
  109. export const ed25519 = /* @__PURE__ */ (() => twistedEdwards(ed25519Defaults))();
  110. function ed25519_domain(data, ctx, phflag) {
  111. if (ctx.length > 255)
  112. throw new Error('Context is too big');
  113. return concatBytes(utf8ToBytes('SigEd25519 no Ed25519 collisions'), new Uint8Array([phflag ? 1 : 0, ctx.length]), ctx, data);
  114. }
  115. export const ed25519ctx = /* @__PURE__ */ (() => twistedEdwards({
  116. ...ed25519Defaults,
  117. domain: ed25519_domain,
  118. }))();
  119. export const ed25519ph = /* @__PURE__ */ (() => twistedEdwards(Object.assign({}, ed25519Defaults, {
  120. domain: ed25519_domain,
  121. prehash: sha512,
  122. })))();
  123. export const x25519 = /* @__PURE__ */ (() => montgomery({
  124. P: ED25519_P,
  125. a: BigInt(486662),
  126. montgomeryBits: 255, // n is 253 bits
  127. nByteLength: 32,
  128. Gu: BigInt(9),
  129. powPminus2: (x) => {
  130. const P = ED25519_P;
  131. // x^(p-2) aka x^(2^255-21)
  132. const { pow_p_5_8, b2 } = ed25519_pow_2_252_3(x);
  133. return mod(pow2(pow_p_5_8, _3n, P) * b2, P);
  134. },
  135. adjustScalarBytes,
  136. randomBytes,
  137. }))();
  138. /**
  139. * Converts ed25519 public key to x25519 public key. Uses formula:
  140. * * `(u, v) = ((1+y)/(1-y), sqrt(-486664)*u/x)`
  141. * * `(x, y) = (sqrt(-486664)*u/v, (u-1)/(u+1))`
  142. * @example
  143. * const someonesPub = ed25519.getPublicKey(ed25519.utils.randomPrivateKey());
  144. * const aPriv = x25519.utils.randomPrivateKey();
  145. * x25519.getSharedSecret(aPriv, edwardsToMontgomeryPub(someonesPub))
  146. */
  147. export function edwardsToMontgomeryPub(edwardsPub) {
  148. const { y } = ed25519.ExtendedPoint.fromHex(edwardsPub);
  149. const _1n = BigInt(1);
  150. return Fp.toBytes(Fp.create((_1n + y) * Fp.inv(_1n - y)));
  151. }
  152. export const edwardsToMontgomery = edwardsToMontgomeryPub; // deprecated
  153. /**
  154. * Converts ed25519 secret key to x25519 secret key.
  155. * @example
  156. * const someonesPub = x25519.getPublicKey(x25519.utils.randomPrivateKey());
  157. * const aPriv = ed25519.utils.randomPrivateKey();
  158. * x25519.getSharedSecret(edwardsToMontgomeryPriv(aPriv), someonesPub)
  159. */
  160. export function edwardsToMontgomeryPriv(edwardsPriv) {
  161. const hashed = ed25519Defaults.hash(edwardsPriv.subarray(0, 32));
  162. return ed25519Defaults.adjustScalarBytes(hashed).subarray(0, 32);
  163. }
  164. // Hash To Curve Elligator2 Map (NOTE: different from ristretto255 elligator)
  165. // NOTE: very important part is usage of FpSqrtEven for ELL2_C1_EDWARDS, since
  166. // SageMath returns different root first and everything falls apart
  167. const ELL2_C1 = /* @__PURE__ */ (() => (Fp.ORDER + _3n) / _8n)(); // 1. c1 = (q + 3) / 8 # Integer arithmetic
  168. const ELL2_C2 = /* @__PURE__ */ (() => Fp.pow(_2n, ELL2_C1))(); // 2. c2 = 2^c1
  169. const ELL2_C3 = /* @__PURE__ */ (() => Fp.sqrt(Fp.neg(Fp.ONE)))(); // 3. c3 = sqrt(-1)
  170. // prettier-ignore
  171. function map_to_curve_elligator2_curve25519(u) {
  172. const ELL2_C4 = (Fp.ORDER - _5n) / _8n; // 4. c4 = (q - 5) / 8 # Integer arithmetic
  173. const ELL2_J = BigInt(486662);
  174. let tv1 = Fp.sqr(u); // 1. tv1 = u^2
  175. tv1 = Fp.mul(tv1, _2n); // 2. tv1 = 2 * tv1
  176. let xd = Fp.add(tv1, Fp.ONE); // 3. xd = tv1 + 1 # Nonzero: -1 is square (mod p), tv1 is not
  177. let x1n = Fp.neg(ELL2_J); // 4. x1n = -J # x1 = x1n / xd = -J / (1 + 2 * u^2)
  178. let tv2 = Fp.sqr(xd); // 5. tv2 = xd^2
  179. let gxd = Fp.mul(tv2, xd); // 6. gxd = tv2 * xd # gxd = xd^3
  180. let gx1 = Fp.mul(tv1, ELL2_J); // 7. gx1 = J * tv1 # x1n + J * xd
  181. gx1 = Fp.mul(gx1, x1n); // 8. gx1 = gx1 * x1n # x1n^2 + J * x1n * xd
  182. gx1 = Fp.add(gx1, tv2); // 9. gx1 = gx1 + tv2 # x1n^2 + J * x1n * xd + xd^2
  183. gx1 = Fp.mul(gx1, x1n); // 10. gx1 = gx1 * x1n # x1n^3 + J * x1n^2 * xd + x1n * xd^2
  184. let tv3 = Fp.sqr(gxd); // 11. tv3 = gxd^2
  185. tv2 = Fp.sqr(tv3); // 12. tv2 = tv3^2 # gxd^4
  186. tv3 = Fp.mul(tv3, gxd); // 13. tv3 = tv3 * gxd # gxd^3
  187. tv3 = Fp.mul(tv3, gx1); // 14. tv3 = tv3 * gx1 # gx1 * gxd^3
  188. tv2 = Fp.mul(tv2, tv3); // 15. tv2 = tv2 * tv3 # gx1 * gxd^7
  189. let y11 = Fp.pow(tv2, ELL2_C4); // 16. y11 = tv2^c4 # (gx1 * gxd^7)^((p - 5) / 8)
  190. y11 = Fp.mul(y11, tv3); // 17. y11 = y11 * tv3 # gx1*gxd^3*(gx1*gxd^7)^((p-5)/8)
  191. let y12 = Fp.mul(y11, ELL2_C3); // 18. y12 = y11 * c3
  192. tv2 = Fp.sqr(y11); // 19. tv2 = y11^2
  193. tv2 = Fp.mul(tv2, gxd); // 20. tv2 = tv2 * gxd
  194. let e1 = Fp.eql(tv2, gx1); // 21. e1 = tv2 == gx1
  195. let y1 = Fp.cmov(y12, y11, e1); // 22. y1 = CMOV(y12, y11, e1) # If g(x1) is square, this is its sqrt
  196. let x2n = Fp.mul(x1n, tv1); // 23. x2n = x1n * tv1 # x2 = x2n / xd = 2 * u^2 * x1n / xd
  197. let y21 = Fp.mul(y11, u); // 24. y21 = y11 * u
  198. y21 = Fp.mul(y21, ELL2_C2); // 25. y21 = y21 * c2
  199. let y22 = Fp.mul(y21, ELL2_C3); // 26. y22 = y21 * c3
  200. let gx2 = Fp.mul(gx1, tv1); // 27. gx2 = gx1 * tv1 # g(x2) = gx2 / gxd = 2 * u^2 * g(x1)
  201. tv2 = Fp.sqr(y21); // 28. tv2 = y21^2
  202. tv2 = Fp.mul(tv2, gxd); // 29. tv2 = tv2 * gxd
  203. let e2 = Fp.eql(tv2, gx2); // 30. e2 = tv2 == gx2
  204. let y2 = Fp.cmov(y22, y21, e2); // 31. y2 = CMOV(y22, y21, e2) # If g(x2) is square, this is its sqrt
  205. tv2 = Fp.sqr(y1); // 32. tv2 = y1^2
  206. tv2 = Fp.mul(tv2, gxd); // 33. tv2 = tv2 * gxd
  207. let e3 = Fp.eql(tv2, gx1); // 34. e3 = tv2 == gx1
  208. let xn = Fp.cmov(x2n, x1n, e3); // 35. xn = CMOV(x2n, x1n, e3) # If e3, x = x1, else x = x2
  209. let y = Fp.cmov(y2, y1, e3); // 36. y = CMOV(y2, y1, e3) # If e3, y = y1, else y = y2
  210. let e4 = Fp.isOdd(y); // 37. e4 = sgn0(y) == 1 # Fix sign of y
  211. y = Fp.cmov(y, Fp.neg(y), e3 !== e4); // 38. y = CMOV(y, -y, e3 XOR e4)
  212. return { xMn: xn, xMd: xd, yMn: y, yMd: _1n }; // 39. return (xn, xd, y, 1)
  213. }
  214. const ELL2_C1_EDWARDS = /* @__PURE__ */ (() => FpSqrtEven(Fp, Fp.neg(BigInt(486664))))(); // sgn0(c1) MUST equal 0
  215. function map_to_curve_elligator2_edwards25519(u) {
  216. const { xMn, xMd, yMn, yMd } = map_to_curve_elligator2_curve25519(u); // 1. (xMn, xMd, yMn, yMd) =
  217. // map_to_curve_elligator2_curve25519(u)
  218. let xn = Fp.mul(xMn, yMd); // 2. xn = xMn * yMd
  219. xn = Fp.mul(xn, ELL2_C1_EDWARDS); // 3. xn = xn * c1
  220. let xd = Fp.mul(xMd, yMn); // 4. xd = xMd * yMn # xn / xd = c1 * xM / yM
  221. let yn = Fp.sub(xMn, xMd); // 5. yn = xMn - xMd
  222. let yd = Fp.add(xMn, xMd); // 6. yd = xMn + xMd # (n / d - 1) / (n / d + 1) = (n - d) / (n + d)
  223. let tv1 = Fp.mul(xd, yd); // 7. tv1 = xd * yd
  224. let e = Fp.eql(tv1, Fp.ZERO); // 8. e = tv1 == 0
  225. xn = Fp.cmov(xn, Fp.ZERO, e); // 9. xn = CMOV(xn, 0, e)
  226. xd = Fp.cmov(xd, Fp.ONE, e); // 10. xd = CMOV(xd, 1, e)
  227. yn = Fp.cmov(yn, Fp.ONE, e); // 11. yn = CMOV(yn, 1, e)
  228. yd = Fp.cmov(yd, Fp.ONE, e); // 12. yd = CMOV(yd, 1, e)
  229. const inv = Fp.invertBatch([xd, yd]); // batch division
  230. return { x: Fp.mul(xn, inv[0]), y: Fp.mul(yn, inv[1]) }; // 13. return (xn, xd, yn, yd)
  231. }
  232. const htf = /* @__PURE__ */ (() => createHasher(ed25519.ExtendedPoint, (scalars) => map_to_curve_elligator2_edwards25519(scalars[0]), {
  233. DST: 'edwards25519_XMD:SHA-512_ELL2_RO_',
  234. encodeDST: 'edwards25519_XMD:SHA-512_ELL2_NU_',
  235. p: Fp.ORDER,
  236. m: 1,
  237. k: 128,
  238. expand: 'xmd',
  239. hash: sha512,
  240. }))();
  241. export const hashToCurve = /* @__PURE__ */ (() => htf.hashToCurve)();
  242. export const encodeToCurve = /* @__PURE__ */ (() => htf.encodeToCurve)();
  243. function assertRstPoint(other) {
  244. if (!(other instanceof RistPoint))
  245. throw new Error('RistrettoPoint expected');
  246. }
  247. // √(-1) aka √(a) aka 2^((p-1)/4)
  248. const SQRT_M1 = ED25519_SQRT_M1;
  249. // √(ad - 1)
  250. const SQRT_AD_MINUS_ONE = /* @__PURE__ */ BigInt('25063068953384623474111414158702152701244531502492656460079210482610430750235');
  251. // 1 / √(a-d)
  252. const INVSQRT_A_MINUS_D = /* @__PURE__ */ BigInt('54469307008909316920995813868745141605393597292927456921205312896311721017578');
  253. // 1-d²
  254. const ONE_MINUS_D_SQ = /* @__PURE__ */ BigInt('1159843021668779879193775521855586647937357759715417654439879720876111806838');
  255. // (d-1)²
  256. const D_MINUS_ONE_SQ = /* @__PURE__ */ BigInt('40440834346308536858101042469323190826248399146238708352240133220865137265952');
  257. // Calculates 1/√(number)
  258. const invertSqrt = (number) => uvRatio(_1n, number);
  259. const MAX_255B = /* @__PURE__ */ BigInt('0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff');
  260. const bytes255ToNumberLE = (bytes) => ed25519.CURVE.Fp.create(bytesToNumberLE(bytes) & MAX_255B);
  261. // Computes Elligator map for Ristretto
  262. // https://ristretto.group/formulas/elligator.html
  263. function calcElligatorRistrettoMap(r0) {
  264. const { d } = ed25519.CURVE;
  265. const P = ed25519.CURVE.Fp.ORDER;
  266. const mod = ed25519.CURVE.Fp.create;
  267. const r = mod(SQRT_M1 * r0 * r0); // 1
  268. const Ns = mod((r + _1n) * ONE_MINUS_D_SQ); // 2
  269. let c = BigInt(-1); // 3
  270. const D = mod((c - d * r) * mod(r + d)); // 4
  271. let { isValid: Ns_D_is_sq, value: s } = uvRatio(Ns, D); // 5
  272. let s_ = mod(s * r0); // 6
  273. if (!isNegativeLE(s_, P))
  274. s_ = mod(-s_);
  275. if (!Ns_D_is_sq)
  276. s = s_; // 7
  277. if (!Ns_D_is_sq)
  278. c = r; // 8
  279. const Nt = mod(c * (r - _1n) * D_MINUS_ONE_SQ - D); // 9
  280. const s2 = s * s;
  281. const W0 = mod((s + s) * D); // 10
  282. const W1 = mod(Nt * SQRT_AD_MINUS_ONE); // 11
  283. const W2 = mod(_1n - s2); // 12
  284. const W3 = mod(_1n + s2); // 13
  285. return new ed25519.ExtendedPoint(mod(W0 * W3), mod(W2 * W1), mod(W1 * W3), mod(W0 * W2));
  286. }
  287. /**
  288. * Each ed25519/ExtendedPoint has 8 different equivalent points. This can be
  289. * a source of bugs for protocols like ring signatures. Ristretto was created to solve this.
  290. * Ristretto point operates in X:Y:Z:T extended coordinates like ExtendedPoint,
  291. * but it should work in its own namespace: do not combine those two.
  292. * https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448
  293. */
  294. class RistPoint {
  295. // Private property to discourage combining ExtendedPoint + RistrettoPoint
  296. // Always use Ristretto encoding/decoding instead.
  297. constructor(ep) {
  298. this.ep = ep;
  299. }
  300. static fromAffine(ap) {
  301. return new RistPoint(ed25519.ExtendedPoint.fromAffine(ap));
  302. }
  303. /**
  304. * Takes uniform output of 64-byte hash function like sha512 and converts it to `RistrettoPoint`.
  305. * The hash-to-group operation applies Elligator twice and adds the results.
  306. * **Note:** this is one-way map, there is no conversion from point to hash.
  307. * https://ristretto.group/formulas/elligator.html
  308. * @param hex 64-byte output of a hash function
  309. */
  310. static hashToCurve(hex) {
  311. hex = ensureBytes('ristrettoHash', hex, 64);
  312. const r1 = bytes255ToNumberLE(hex.slice(0, 32));
  313. const R1 = calcElligatorRistrettoMap(r1);
  314. const r2 = bytes255ToNumberLE(hex.slice(32, 64));
  315. const R2 = calcElligatorRistrettoMap(r2);
  316. return new RistPoint(R1.add(R2));
  317. }
  318. /**
  319. * Converts ristretto-encoded string to ristretto point.
  320. * https://ristretto.group/formulas/decoding.html
  321. * @param hex Ristretto-encoded 32 bytes. Not every 32-byte string is valid ristretto encoding
  322. */
  323. static fromHex(hex) {
  324. hex = ensureBytes('ristrettoHex', hex, 32);
  325. const { a, d } = ed25519.CURVE;
  326. const P = ed25519.CURVE.Fp.ORDER;
  327. const mod = ed25519.CURVE.Fp.create;
  328. const emsg = 'RistrettoPoint.fromHex: the hex is not valid encoding of RistrettoPoint';
  329. const s = bytes255ToNumberLE(hex);
  330. // 1. Check that s_bytes is the canonical encoding of a field element, or else abort.
  331. // 3. Check that s is non-negative, or else abort
  332. if (!equalBytes(numberToBytesLE(s, 32), hex) || isNegativeLE(s, P))
  333. throw new Error(emsg);
  334. const s2 = mod(s * s);
  335. const u1 = mod(_1n + a * s2); // 4 (a is -1)
  336. const u2 = mod(_1n - a * s2); // 5
  337. const u1_2 = mod(u1 * u1);
  338. const u2_2 = mod(u2 * u2);
  339. const v = mod(a * d * u1_2 - u2_2); // 6
  340. const { isValid, value: I } = invertSqrt(mod(v * u2_2)); // 7
  341. const Dx = mod(I * u2); // 8
  342. const Dy = mod(I * Dx * v); // 9
  343. let x = mod((s + s) * Dx); // 10
  344. if (isNegativeLE(x, P))
  345. x = mod(-x); // 10
  346. const y = mod(u1 * Dy); // 11
  347. const t = mod(x * y); // 12
  348. if (!isValid || isNegativeLE(t, P) || y === _0n)
  349. throw new Error(emsg);
  350. return new RistPoint(new ed25519.ExtendedPoint(x, y, _1n, t));
  351. }
  352. /**
  353. * Encodes ristretto point to Uint8Array.
  354. * https://ristretto.group/formulas/encoding.html
  355. */
  356. toRawBytes() {
  357. let { ex: x, ey: y, ez: z, et: t } = this.ep;
  358. const P = ed25519.CURVE.Fp.ORDER;
  359. const mod = ed25519.CURVE.Fp.create;
  360. const u1 = mod(mod(z + y) * mod(z - y)); // 1
  361. const u2 = mod(x * y); // 2
  362. // Square root always exists
  363. const u2sq = mod(u2 * u2);
  364. const { value: invsqrt } = invertSqrt(mod(u1 * u2sq)); // 3
  365. const D1 = mod(invsqrt * u1); // 4
  366. const D2 = mod(invsqrt * u2); // 5
  367. const zInv = mod(D1 * D2 * t); // 6
  368. let D; // 7
  369. if (isNegativeLE(t * zInv, P)) {
  370. let _x = mod(y * SQRT_M1);
  371. let _y = mod(x * SQRT_M1);
  372. x = _x;
  373. y = _y;
  374. D = mod(D1 * INVSQRT_A_MINUS_D);
  375. }
  376. else {
  377. D = D2; // 8
  378. }
  379. if (isNegativeLE(x * zInv, P))
  380. y = mod(-y); // 9
  381. let s = mod((z - y) * D); // 10 (check footer's note, no sqrt(-a))
  382. if (isNegativeLE(s, P))
  383. s = mod(-s);
  384. return numberToBytesLE(s, 32); // 11
  385. }
  386. toHex() {
  387. return bytesToHex(this.toRawBytes());
  388. }
  389. toString() {
  390. return this.toHex();
  391. }
  392. // Compare one point to another.
  393. equals(other) {
  394. assertRstPoint(other);
  395. const { ex: X1, ey: Y1 } = this.ep;
  396. const { ex: X2, ey: Y2 } = other.ep;
  397. const mod = ed25519.CURVE.Fp.create;
  398. // (x1 * y2 == y1 * x2) | (y1 * y2 == x1 * x2)
  399. const one = mod(X1 * Y2) === mod(Y1 * X2);
  400. const two = mod(Y1 * Y2) === mod(X1 * X2);
  401. return one || two;
  402. }
  403. add(other) {
  404. assertRstPoint(other);
  405. return new RistPoint(this.ep.add(other.ep));
  406. }
  407. subtract(other) {
  408. assertRstPoint(other);
  409. return new RistPoint(this.ep.subtract(other.ep));
  410. }
  411. multiply(scalar) {
  412. return new RistPoint(this.ep.multiply(scalar));
  413. }
  414. multiplyUnsafe(scalar) {
  415. return new RistPoint(this.ep.multiplyUnsafe(scalar));
  416. }
  417. double() {
  418. return new RistPoint(this.ep.double());
  419. }
  420. negate() {
  421. return new RistPoint(this.ep.negate());
  422. }
  423. }
  424. export const RistrettoPoint = /* @__PURE__ */ (() => {
  425. if (!RistPoint.BASE)
  426. RistPoint.BASE = new RistPoint(ed25519.ExtendedPoint.BASE);
  427. if (!RistPoint.ZERO)
  428. RistPoint.ZERO = new RistPoint(ed25519.ExtendedPoint.ZERO);
  429. return RistPoint;
  430. })();
  431. // Hashing to ristretto255. https://www.rfc-editor.org/rfc/rfc9380#appendix-B
  432. export const hashToRistretto255 = (msg, options) => {
  433. const d = options.DST;
  434. const DST = typeof d === 'string' ? utf8ToBytes(d) : d;
  435. const uniform_bytes = expand_message_xmd(msg, DST, 64, sha512);
  436. const P = RistPoint.hashToCurve(uniform_bytes);
  437. return P;
  438. };
  439. export const hash_to_ristretto255 = hashToRistretto255; // legacy
  440. //# sourceMappingURL=ed25519.js.map