Re: [PATCH] crypto: crypto4xx - Remove insecure and unused rng_alg

[Herbert Xu <herbert@gondor.apana.org.au>]

On Fri, May 29, 2026 at 03:04:30PM -0700, Eric Biggers wrote:
> Remove crypto4xx_rng, as it is insecure and unused:
> 
> - It has only a 64-bit security strength, which is highly inadequate.
>   This can be seen by the fact that crypto4xx_hw_init() seeds it with
>   only 64 bits of entropy, and the fact that the original commit
>   mentions that it implements ANSI X9.17 Annex C.
> 
>   Another issue was that this driver didn't implement the crypto_rng API
>   correctly, as crypto4xx_prng_generate() didn't return 0 on success.
> 
> - No user of this code is known.  It's usable only theoretically via the
>   "rng" algorithm type of AF_ALG.  But userspace actually just uses the
>   actual Linux RNG (/dev/random etc) instead.  And rng_algs don't
>   contribute entropy to the actual Linux RNG either.  (This may have
>   been confused with hwrng, which does contribute entropy.)
> 
> Fixes: d072bfa48853 ("crypto: crypto4xx - add prng crypto support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@kernel.org>
> ---
>  drivers/crypto/Kconfig                  |  1 -
>  drivers/crypto/amcc/crypto4xx_core.c    | 88 -------------------------
>  drivers/crypto/amcc/crypto4xx_core.h    |  4 --
>  drivers/crypto/amcc/crypto4xx_reg_def.h | 11 ----
>  4 files changed, 104 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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