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35 lines
1.1 KiB
35 lines
1.1 KiB
var BN = require('bn.js') |
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var randomBytes = require('randombytes') |
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function blind (priv) { |
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var r = getr(priv) |
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var blinder = r.toRed(BN.mont(priv.modulus)).redPow(new BN(priv.publicExponent)).fromRed() |
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return { blinder: blinder, unblinder: r.invm(priv.modulus) } |
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} |
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function getr (priv) { |
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var len = priv.modulus.byteLength() |
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var r |
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do { |
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r = new BN(randomBytes(len)) |
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} while (r.cmp(priv.modulus) >= 0 || !r.umod(priv.prime1) || !r.umod(priv.prime2)) |
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return r |
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} |
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function crt (msg, priv) { |
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var blinds = blind(priv) |
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var len = priv.modulus.byteLength() |
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var blinded = new BN(msg).mul(blinds.blinder).umod(priv.modulus) |
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var c1 = blinded.toRed(BN.mont(priv.prime1)) |
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var c2 = blinded.toRed(BN.mont(priv.prime2)) |
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var qinv = priv.coefficient |
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var p = priv.prime1 |
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var q = priv.prime2 |
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var m1 = c1.redPow(priv.exponent1).fromRed() |
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var m2 = c2.redPow(priv.exponent2).fromRed() |
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var h = m1.isub(m2).imul(qinv).umod(p).imul(q) |
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return m2.iadd(h).imul(blinds.unblinder).umod(priv.modulus).toArrayLike(Buffer, 'be', len) |
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} |
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crt.getr = getr |
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module.exports = crt
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