+
+/* rand_hw_seed: get seed data from any available hardware RNG.
+ * only currently supports rdrand.
+ */
+
+/* Adapted from eng_rdrand.c */
+
+#if (defined(__i386) || defined(__i386__) || defined(_M_IX86) || \
+ defined(__x86_64) || defined(__x86_64__) || \
+ defined(_M_AMD64) || defined (_M_X64)) && defined(OPENSSL_CPUID_OBJ)
+
+#define RDRAND_CALLS 4
+
+size_t OPENSSL_ia32_rdrand(void);
+extern unsigned int OPENSSL_ia32cap_P[];
+
+static void rand_hw_seed(EVP_MD_CTX *ctx)
+ {
+ int i;
+ if (!(OPENSSL_ia32cap_P[1] & (1<<(62-32))))
+ return;
+ for (i = 0; i < RDRAND_CALLS; i++)
+ {
+ size_t rnd;
+ rnd = OPENSSL_ia32_rdrand();
+ if (rnd == 0)
+ return;
+ MD_Update(ctx, (unsigned char *)&rnd, sizeof(size_t));
+ }
+ }
+
+/* XOR an existing buffer with random data */
+
+void rand_hw_xor(unsigned char *buf, size_t num)
+ {
+ size_t rnd;
+ if (!(OPENSSL_ia32cap_P[1] & (1<<(62-32))))
+ return;
+ while (num >= sizeof(size_t))
+ {
+ rnd = OPENSSL_ia32_rdrand();
+ if (rnd == 0)
+ return;
+ *((size_t *)buf) ^= rnd;
+ buf += sizeof(size_t);
+ num -= sizeof(size_t);
+ }
+ if (num)
+ {
+ rnd = OPENSSL_ia32_rdrand();
+ if (rnd == 0)
+ return;
+ while(num)
+ {
+ *buf ^= rnd & 0xff;
+ rnd >>= 8;
+ buf++;
+ num--;
+ }
+ }
+ }
+
+
+#else
+
+static void rand_hw_seed(EVP_MD_CTX *ctx)
+ {
+ return;
+ }
+
+void rand_hw_xor(unsigned char *buf, size_t num)
+ {
+ return;
+ }
+
+#endif