Implement BN_rand_range

src/ssl.c

@@ -52693,11 +52693,10 @@ int wolfSSL_mask_bits(WOLFSSL_BIGNUM* bn, int n)
 }
 #endif
 
-
 /* WOLFSSL_SUCCESS on ok */
 int wolfSSL_BN_rand(WOLFSSL_BIGNUM* bn, int bits, int top, int bottom)
 {
-    int           ret    = 0;
+    int           ret    = WOLFSSL_FAILURE;
     int           len;
     int           initTmpRng = 0;
     WC_RNG*       rng    = NULL;
@@ -52770,6 +52769,38 @@ int wolfSSL_BN_rand(WOLFSSL_BIGNUM* bn, int bits, int top, int bottom)
     return ret;
 }
 
+/**
+ * N = length of range input var
+ * Generate N-bit length numbers until generated number is less than range
+ * @param r     Output number
+ * @param range The upper limit of generated output
+ * @return WOLFSSL_SUCCESS on success and WOLFSSL_FAILURE on failure
+ */
+int wolfSSL_BN_rand_range(WOLFSSL_BIGNUM *r, const WOLFSSL_BIGNUM *range)
+{
+    int n;
+    WOLFSSL_MSG("wolfSSL_BN_rand_range");
+
+    if (r == NULL || range == NULL) {
+        WOLFSSL_MSG("Bad parameter");
+        return WOLFSSL_FAILURE;
+    }
+
+    n = wolfSSL_BN_num_bits(range);
+
+    if (n <= 1) {
+        wolfSSL_BN_zero(r);
+    }
+    else {
+        do {
+            if (wolfSSL_BN_rand(r, n, 0, 0) == WOLFSSL_FAILURE) {
+                WOLFSSL_MSG("wolfSSL_BN_rand error");
+                return WOLFSSL_FAILURE;
+            }
+        } while(wolfSSL_BN_cmp(r, range) >= 0);
+    }
+    return WOLFSSL_SUCCESS;
+}
 
 /* WOLFSSL_SUCCESS on ok
  * code is same as wolfSSL_BN_rand except for how top and bottom is handled.

tests/api.c

@@ -36775,6 +36775,7 @@ static void test_wolfSSL_BN_rand(void)
 {
     #if defined(OPENSSL_EXTRA)
     BIGNUM* bn;
+    BIGNUM* range;
 
     printf(testingFmt, "wolfSSL_BN_rand()");
 
@@ -36790,6 +36791,13 @@ static void test_wolfSSL_BN_rand(void)
     AssertIntEQ(BN_rand(bn, 64, 0, 0), SSL_SUCCESS);
     BN_free(bn);
 
+    AssertNotNull(bn = BN_new());
+    AssertNotNull(range = BN_new());
+    AssertIntEQ(BN_rand(range, 64, 0, 0), SSL_SUCCESS);
+    AssertIntEQ(BN_rand_range(bn, range), SSL_SUCCESS);
+    BN_free(bn);
+    BN_free(range);
+
     printf(resultFmt, passed);
     #endif
 }

wolfssl/openssl/bn.h

@@ -104,6 +104,7 @@ WOLFSSL_API int wolfSSL_mask_bits(WOLFSSL_BIGNUM*, int n);
 
 WOLFSSL_API int wolfSSL_BN_pseudo_rand(WOLFSSL_BIGNUM*, int bits, int top,
         int bottom);
+WOLFSSL_API int wolfSSL_BN_rand_range(WOLFSSL_BIGNUM *r, const WOLFSSL_BIGNUM *range);
 WOLFSSL_API int wolfSSL_BN_rand(WOLFSSL_BIGNUM*, int bits, int top, int bottom);
 WOLFSSL_API int wolfSSL_BN_is_bit_set(const WOLFSSL_BIGNUM*, int n);
 WOLFSSL_API int wolfSSL_BN_hex2bn(WOLFSSL_BIGNUM**, const char* str);
@@ -187,6 +188,7 @@ typedef WOLFSSL_BN_GENCB BN_GENCB;
 
 #define BN_pseudo_rand wolfSSL_BN_pseudo_rand
 #define BN_rand        wolfSSL_BN_rand
+#define BN_rand_range  wolfSSL_BN_rand_range
 #define BN_is_bit_set  wolfSSL_BN_is_bit_set
 #define BN_hex2bn      wolfSSL_BN_hex2bn