On Tue, 22 Apr 2025 at 11:57, Marek Behún <kabel@xxxxxxxxxx> wrote: > > According to the review by Bill Cox [1], the Atmel SHA204A random number > generator produces random numbers with very low entropy. > > Set the lowest possible entropy for this chip just to be safe. > > [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html > > Fixes: da001fb651b00e1d ("crypto: atmel-i2c - add support for SHA204A random number generator") > Signed-off-by: Marek Behún <kabel@xxxxxxxxxx> > --- > drivers/crypto/atmel-sha204a.c | 6 ++++++ > 1 file changed, 6 insertions(+) > Wow, that is terrible Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c > index 75bebec2c757..0fcf4a39de27 100644 > --- a/drivers/crypto/atmel-sha204a.c > +++ b/drivers/crypto/atmel-sha204a.c > @@ -163,6 +163,12 @@ static int atmel_sha204a_probe(struct i2c_client *client) > i2c_priv->hwrng.name = dev_name(&client->dev); > i2c_priv->hwrng.read = atmel_sha204a_rng_read; > > + /* > + * According to review by Bill Cox [1], this HWRNG has very low entropy. > + * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html > + */ > + i2c_priv->hwrng.quality = 1; > + > ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng); > if (ret) > dev_warn(&client->dev, "failed to register RNG (%d)\n", ret); > -- > 2.49.0 >
