77 lines
1.7 KiB
JavaScript
77 lines
1.7 KiB
JavaScript
/* eslint-disable camelcase, one-var */
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const { _9, _121665, gf, inv25519, pack25519, unpack25519, sel25519, A, M, Z, S } = require('./internal/ed25519')
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const crypto_scalarmult_BYTES = 32
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const crypto_scalarmult_SCALARBYTES = 32
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module.exports = {
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crypto_scalarmult,
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crypto_scalarmult_base,
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crypto_scalarmult_BYTES,
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crypto_scalarmult_SCALARBYTES
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}
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function crypto_scalarmult (q, n, p) {
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check(q, crypto_scalarmult_BYTES)
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check(n, crypto_scalarmult_SCALARBYTES)
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check(p, crypto_scalarmult_BYTES)
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var z = new Uint8Array(32)
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var x = new Float64Array(80), r, i
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var a = gf(), b = gf(), c = gf(),
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d = gf(), e = gf(), f = gf()
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for (i = 0; i < 31; i++) z[i] = n[i]
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z[31] = (n[31] & 127) | 64
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z[0] &= 248
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unpack25519(x, p)
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for (i = 0; i < 16; i++) {
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b[i] = x[i]
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d[i] = a[i] = c[i] = 0
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}
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a[0] = d[0] = 1
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for (i = 254; i >= 0; --i) {
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r = (z[i >>> 3] >>> (i & 7)) & 1
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sel25519(a, b, r)
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sel25519(c, d, r)
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A(e, a, c)
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Z(a, a, c)
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A(c, b, d)
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Z(b, b, d)
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S(d, e)
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S(f, a)
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M(a, c, a)
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M(c, b, e)
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A(e, a, c)
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Z(a, a, c)
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S(b, a)
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Z(c, d, f)
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M(a, c, _121665)
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A(a, a, d)
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M(c, c, a)
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M(a, d, f)
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M(d, b, x)
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S(b, e)
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sel25519(a, b, r)
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sel25519(c, d, r)
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}
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for (i = 0; i < 16; i++) {
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x[i + 16] = a[i]
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x[i + 32] = c[i]
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x[i + 48] = b[i]
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x[i + 64] = d[i]
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}
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var x32 = x.subarray(32)
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var x16 = x.subarray(16)
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inv25519(x32, x32)
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M(x16, x16, x32)
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pack25519(q, x16)
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return 0
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}
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function crypto_scalarmult_base (q, n) {
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return crypto_scalarmult(q, n, _9)
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}
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function check (buf, len) {
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if (!buf || (len && buf.length < len)) throw new Error('Argument must be a buffer' + (len ? ' of length ' + len : ''))
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}
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