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browserify_rsa.js
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browserify_rsa.js
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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
// Copyright 2017 crypto-browserify. All rights reserved. MIT license.
import { BN } from "./bn.js/bn.js";
import { randomBytes } from "./randombytes.ts";
import { Buffer } from "../../buffer.ts";
function blind(priv) {
const r = getr(priv);
const blinder = r.toRed(BN.mont(priv.modulus)).redPow(
new BN(priv.publicExponent),
).fromRed();
return { blinder: blinder, unblinder: r.invm(priv.modulus) };
}
function getr(priv) {
const len = priv.modulus.byteLength();
let r;
do {
r = new BN(randomBytes(len));
} while (
r.cmp(priv.modulus) >= 0 || !r.umod(priv.prime1) || !r.umod(priv.prime2)
);
return r;
}
function crt(msg, priv) {
const blinds = blind(priv);
const len = priv.modulus.byteLength();
const blinded = new BN(msg).mul(blinds.blinder).umod(priv.modulus);
const c1 = blinded.toRed(BN.mont(priv.prime1));
const c2 = blinded.toRed(BN.mont(priv.prime2));
const qinv = priv.coefficient;
const p = priv.prime1;
const q = priv.prime2;
const m1 = c1.redPow(priv.exponent1).fromRed();
const m2 = c2.redPow(priv.exponent2).fromRed();
const h = m1.isub(m2).imul(qinv).umod(p).imul(q);
return m2.iadd(h).imul(blinds.unblinder).umod(priv.modulus).toArrayLike(
Buffer,
"be",
len,
);
}
crt.getr = getr;
export default crt;