Re: [PATCH v2 2/3] crypto: add RSA support

[Sascha Hauer <s.hauer@pengutronix.de>]

On Thu, Jan 07, 2016 at 10:03:10PM +0000, Trent Piepho wrote:
> On Wed, 2016-01-06 at 18:01 +0100, Marc Kleine-Budde wrote:
> > +
> > +static void rsa_convert_big_endian(uint32_t *dst, const uint32_t *src, int len)
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < len; i++)
> > +		dst[i] = fdt32_to_cpu(src[len - 1 - i]);
> > +}
> > +
> 
> 
> > +struct rsa_public_key {
> > +	uint len;		/* len of modulus[] in number of uint32_t */
> > +	uint32_t n0inv;		/* -1 / modulus[0] mod 2^32 */
> > +	uint32_t *modulus;	/* modulus as little endian array */
> > +	uint32_t *rr;		/* R^2 as little endian array */
> > +	uint64_t exponent;	/* public exponent */
> 
> This says little endian, but it looks like it's really CPU endian, i.e.
> on a big endian system it would be big endian.

Indeed the original author of this code must have assumed that big
endian systems do not exist. Here's another one:

> +     /* Convert from big endian byte array to little endian word array. */
> +     for (i = 0, ptr = inout + key->len - 1; i < key->len; i++, ptr--)
> +             val[i] = get_unaligned_be32(ptr);

It "little endian" comments should be replaced by "cpu endian" in the
comments.

Sascha

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