#include <assert.h>
#include <limits.h>
-#include <stdio.h>
#include "cryptlib.h"
#include "bn_lcl.h"
BNerr(BN_F_BN_EXPAND_INTERNAL,ERR_R_MALLOC_FAILURE);
return(NULL);
}
+#ifdef PURIFY
+ /* Valgrind complains in BN_consttime_swap because we process the whole
+ * array even if it's not initialised yet. This doesn't matter in that
+ * function - what's important is constant time operation (we're not
+ * actually going to use the data)
+ */
+ memset(a, 0, sizeof(BN_ULONG)*words);
+#endif
+
#if 1
B=b->d;
/* Check if the previous number needs to be copied */
}
return bn_cmp_words(a,b,cl);
}
+
+/*
+ * Constant-time conditional swap of a and b.
+ * a and b are swapped if condition is not 0. The code assumes that at most one bit of condition is set.
+ * nwords is the number of words to swap. The code assumes that at least nwords are allocated in both a and b,
+ * and that no more than nwords are used by either a or b.
+ * a and b cannot be the same number
+ */
+void BN_consttime_swap(BN_ULONG condition, BIGNUM *a, BIGNUM *b, int nwords)
+ {
+ BN_ULONG t;
+ int i;
+
+ bn_wcheck_size(a, nwords);
+ bn_wcheck_size(b, nwords);
+
+ assert(a != b);
+ assert((condition & (condition - 1)) == 0);
+ assert(sizeof(BN_ULONG) >= sizeof(int));
+
+ condition = ((condition - 1) >> (BN_BITS2 - 1)) - 1;
+
+ t = (a->top^b->top) & condition;
+ a->top ^= t;
+ b->top ^= t;
+
+#define BN_CONSTTIME_SWAP(ind) \
+ do { \
+ t = (a->d[ind] ^ b->d[ind]) & condition; \
+ a->d[ind] ^= t; \
+ b->d[ind] ^= t; \
+ } while (0)
+
+
+ switch (nwords) {
+ default:
+ for (i = 10; i < nwords; i++)
+ BN_CONSTTIME_SWAP(i);
+ /* Fallthrough */
+ case 10: BN_CONSTTIME_SWAP(9); /* Fallthrough */
+ case 9: BN_CONSTTIME_SWAP(8); /* Fallthrough */
+ case 8: BN_CONSTTIME_SWAP(7); /* Fallthrough */
+ case 7: BN_CONSTTIME_SWAP(6); /* Fallthrough */
+ case 6: BN_CONSTTIME_SWAP(5); /* Fallthrough */
+ case 5: BN_CONSTTIME_SWAP(4); /* Fallthrough */
+ case 4: BN_CONSTTIME_SWAP(3); /* Fallthrough */
+ case 3: BN_CONSTTIME_SWAP(2); /* Fallthrough */
+ case 2: BN_CONSTTIME_SWAP(1); /* Fallthrough */
+ case 1: BN_CONSTTIME_SWAP(0);
+ }
+#undef BN_CONSTTIME_SWAP
+}
+
+/* Bits of security, see SP800-57 */
+
+int BN_security_bits(int L, int N)
+ {
+ int secbits, bits;
+ if (L >= 15360)
+ secbits = 256;
+ else if (L >= 7690)
+ secbits = 192;
+ else if (L >= 3072)
+ secbits = 128;
+ else if (L >= 2048)
+ secbits = 112;
+ else if (L >= 1024)
+ secbits = 80;
+ else
+ return 0;
+ if (N == -1)
+ return secbits;
+ bits = N / 2;
+ if (bits < 80)
+ return 0;
+ return bits >= secbits ? secbits : bits;
+ }