gistfile1.coffee

    # Cryptographic blinding: compute random r,
    # r_e <- r^e mod n
    # and x <- x*r_e mod n
    n = @pub.n
    await SRF().random_zn n, defer r
    r_inv = r.modInverse(n) 
    r_e = r.modPow(@pub.e,n)
    x_1 = x.multiply(r_e).mod(n)

    # calculate xp and xq
    xp = x_1.mod(@p).modPow(@dP, @p)
    xq = x_1.mod(@q).modPow(@dQ, @q)

    # xp must be larger than xq to avoid signed bit usage
    while xp.compareTo(xq) < 0
      xp = xp.add @p

    # do last step
    y_0 = xp.subtract(xq).multiply(@qInv).mod(@p).multiply(@q).add(xq)

    # multiply by r^-1...
    y = y_0.multiply(r_inv).mod(n)

    cb y