Dmitry Eremin-Solenikov <dbarysh...@gmail.com> writes:
> Hash function GOST R 34.11-94 (gosthash94) in its compression function
> uses Russian block cipher (GOST 28147-89, Magma). Start separating block
> cipher code from hash function code. For now there is no public
> interface for this cipher, it will be added later.
I'm having an initial look at this, with a few comments.
> --- /dev/null
> +++ b/gost28147.c
> +/*
> + * A macro that performs a full encryption round of GOST 28147-89.
> + * Temporary variables tmp assumed and variables r and l for left and right
> + * blocks.
> + */
> +#define GOST_ENCRYPT_ROUND(key1, key2, sbox) \
> + tmp = (key1) + r; \
> + l ^= (sbox)[0*256 + (tmp & 0xff)] ^ (sbox)[1*256 + ((tmp >> 8) & 0xff)] ^ \
> + (sbox)[2*256 + ((tmp >> 16) & 0xff)] ^ (sbox)[3*256 + (tmp >> 24)]; \
> + tmp = (key2) + l; \
> + r ^= (sbox)[0*256 + (tmp & 0xff)] ^ (sbox)[1*256 + ((tmp >> 8) & 0xff)] ^ \
> + (sbox)[2*256 + ((tmp >> 16) & 0xff)] ^ (sbox)[3*256 + (tmp >> 24)];
This code is just moved around in this patch, but I'd like to note that
it's preferable to always wrap function-like macros like this in do { ... }
while (0), and when used terminate with ;. And avoid using surrounding
variables; r and l could be macro arguments, and tmp (with some likely
unique prefix) could be a local in the do { ... } while block.
> --- /dev/null
> +++ b/gost28147.h
> @@ -0,0 +1,63 @@
> +struct gost28147_param
> +{
> + uint32_t sbox[4*256];
> +};
Why change to a flat array, and not keep it as
uint32_t sbox[4][256];
?
> +extern const struct gost28147_param gost28147_param_test_3411;
I find "test" in the name a bit odd. Is there a reason for that? And
declaration should probably not be in an installed header file, but in
gost-internal.h or so.
> +/* Internal interface for use by GOST R 34.11-94 */
> +void gost28147_encrypt_simple (const uint32_t *key, const uint32_t *sbox,
> + const uint32_t *in, uint32_t *out);
Same here: if internal, shouldn't be in an installed header file. And
"simple" looks a bit odd.
Should the sbox argument be of type const gost28147_param * ?
Regards,
/Niels
--
Niels Möller. PGP-encrypted email is preferred. Keyid 368C6677.
Internet email is subject to wholesale government surveillance.
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