Compute M-R trials for RSA in case of LTM_USE_ONLY_MR

Author: czurnieden

mp_prime_rabin_miller_trials.c

@@ -4,35 +4,46 @@
 /* SPDX-License-Identifier: Unlicense */
 
 static const struct {
-   int k, t;
+   int k, t, e;
 } sizes[] = {
-   {    80, -1 }, /* Use deterministic algorithm for size <= 80 bits */
-   {    81, 37 }, /* max. error = 2^(-96)*/
-   {    96, 32 }, /* max. error = 2^(-96)*/
-   {   128, 40 }, /* max. error = 2^(-112)*/
-   {   160, 35 }, /* max. error = 2^(-112)*/
-   {   256, 27 }, /* max. error = 2^(-128)*/
-   {   384, 16 }, /* max. error = 2^(-128)*/
-   {   512, 18 }, /* max. error = 2^(-160)*/
-   {   768, 11 }, /* max. error = 2^(-160)*/
-   {   896, 10 }, /* max. error = 2^(-160)*/
-   {  1024, 12 }, /* max. error = 2^(-192)*/
-   {  1536, 8  }, /* max. error = 2^(-192)*/
-   {  2048, 6  }, /* max. error = 2^(-192)*/
-   {  3072, 4  }, /* max. error = 2^(-192)*/
-   {  4096, 5  }, /* max. error = 2^(-256)*/
-   {  5120, 4  }, /* max. error = 2^(-256)*/
-   {  6144, 4  }, /* max. error = 2^(-256)*/
-   {  8192, 3  }, /* max. error = 2^(-256)*/
-   {  9216, 3  }, /* max. error = 2^(-256)*/
-   { 10240, 2  }  /* For bigger keysizes use always at least 2 Rounds */
+   {    80, -1, 96},  /* Use deterministic algorithm for size <= 80 bits */
+   {    81, 37, 96},  /* max. error = 2^(-96)*/
+   {    96, 32, 96},  /* max. error = 2^(-96)*/
+   {   128, 40, 112}, /* max. error = 2^(-112)*/
+   {   160, 35, 112}, /* max. error = 2^(-112)*/
+   {   256, 27, 128}, /* max. error = 2^(-128)*/
+   {   384, 16, 128}, /* max. error = 2^(-128)*/
+   {   512, 18, 160}, /* max. error = 2^(-160)*/
+   {   768, 11, 160}, /* max. error = 2^(-160)*/
+   {   896, 10, 160}, /* max. error = 2^(-160)*/
+   {  1024, 12, 192}, /* max. error = 2^(-192)*/
+   {  1536, 8,  192}, /* max. error = 2^(-192)*/
+   {  2048, 6,  192}, /* max. error = 2^(-192)*/
+   {  3072, 4,  192}, /* max. error = 2^(-192)*/
+   {  4096, 5,  256}, /* max. error = 2^(-256)*/
+   {  5120, 4,  256}, /* max. error = 2^(-256)*/
+   {  6144, 4,  256}, /* max. error = 2^(-256)*/
+   {  8192, 3,  256}, /* max. error = 2^(-256)*/
+   {  9216, 3,  256}, /* max. error = 2^(-256)*/
+   { 10240, 2,  256}  /* For bigger keysizes use always at least 2 Rounds */
 };
 
 /* returns # of RM trials required for a given bit size */
 int mp_prime_rabin_miller_trials(int size)
 {
    int x;
-
+#ifdef LTM_USE_ONLY_MR
+   for (x = 0; x < (int)(sizeof(sizes)/(sizeof(sizes[0]))); x++) {
+      if (sizes[x].k == size) {
+         return mp_prime_rabin_miller_trials_dea(sizes[x].e);
+      }
+      if (sizes[x].k > size) {
+         return (x == 0) ? mp_prime_rabin_miller_trials_dea(sizes[0].e) :
+                mp_prime_rabin_miller_trials_dea(sizes[x - 1].e);
+      }
+   }
+   return mp_prime_rabin_miller_trials_dea(sizes[x - 1].e);
+#else
    for (x = 0; x < (int)(sizeof(sizes)/(sizeof(sizes[0]))); x++) {
       if (sizes[x].k == size) {
          return sizes[x].t;
@@ -42,6 +53,7 @@ int mp_prime_rabin_miller_trials(int size)
       }
    }
    return sizes[x-1].t;
+#endif
 }