Hi Chris,

I am trying with the USE_FAST_MATH and TFM_TIMING_RESISTANT configuration. We have a 32 bit processor, could you please further advice how to configure for 32 bit processor with USE_FAST_MATH. I have tried with the following:

#undef FP_64BIT
#undef CRYPT 

and modified

typedef unsigned int  fp_digit 

to

typedef unsigned short fp_digit

.
Without this modification, I got the following compilation error:

ctaocrypt/src/tfm.c:105: warning: shifting an `unsigned long long' by 32 bits is undefined

However, using USE_FAST_MATH it was not faster for RSA, but even slower. So I assume that I am using the wrong configuration.

Additionally, I realized sizeof(mp_int) = 16 in case of without the fast math lib, and sizeof(mp_int) = 552, is it correct?

Thanks, Yun

Hi Chris,

Sorry for the late response! I have using a 32 bit processor environment, and the lcc compiler. As far as I know, lcc does not have 64bit support.

Without USE_FAST_MATH, I have the following configuration for the 32bit environment, and everything worked fine.

#define MP_16BIT
#define CHAR_BIT      8

Now, I added

#define SIZEOF_LONG 4
#define SIZEOF_LONG_LONG 4

I still got the warning:

ctaocrypt/src/tfm.c:105: warning: shifting an `unsigned long long' by 32 bits is undefined

.

In tfm.h, DIGIT_BIT is defined as

#define DIGIT_BIT  (int)((CHAR_BIT) * sizeof(fp_digit))

which is 32. So I cannot get rid of the above warning.

What shall I do to get USE_FAST_MATH working for a 32 bit environment?

Thanks, Yun