Blinding implementation in OpenSSL

Tomas Mraz tmraz at
Mon Apr 15 12:58:40 UTC 2019

On Mon, 2019-04-15 at 10:39 +0300, Dmitry Belyavsky wrote:
> Hello,
> Could you please explain how blinding works in OpenSSL?
> EC_KEY structure seems to have an unblinded private key structure and
> blinded X, Y, Z- coordinates of the public key when blinding is in
> use. But if I understand correctly, he idea of blinding is protecting
> the private key from extracting from memory/swap/etc? Am I wrong?

No, blinding is done during the private key operations to "randomize"
the computations so timing and other side channels do not leak the
private key. The private key itself is not modified.

Tomáš Mráz
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