1 files changed, 82 insertions, 0 deletions
diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c
index 1254415a43..4f6445434b 100644
--- a/crypto/bn/bn_exp.c
+++ b/crypto/bn/bn_exp.c
@@ -1390,3 +1390,85 @@ int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
     bn_check_top(r);
     return ret;
 }
+
+/*
+ * This is a variant of modular exponentiation optimization that does
+ * parallel 2-primes exponentiation using 256-bit (AVX512VL) AVX512_IFMA ISA
+ * in 52-bit binary redundant representation.
+ * If such instructions are not available, or input data size is not supported,
+ * it falls back to two BN_mod_exp_mont_consttime() calls.
+ */
+int BN_mod_exp_mont_consttime_x2(BIGNUM *rr1, const BIGNUM *a1, const BIGNUM *p1,
+                                 const BIGNUM *m1, BN_MONT_CTX *in_mont1,
+                                 BIGNUM *rr2, const BIGNUM *a2, const BIGNUM *p2,
+                                 const BIGNUM *m2, BN_MONT_CTX *in_mont2,
+                                 BN_CTX *ctx)
+{
+    int ret = 0;
+
+#ifdef RSAZ_ENABLED
+    BN_MONT_CTX *mont1 = NULL;
+    BN_MONT_CTX *mont2 = NULL;
+
+    if (rsaz_avx512ifma_eligible() &&
+        ((a1->top == 16) && (p1->top == 16) && (BN_num_bits(m1) == 1024) &&
+         (a2->top == 16) && (p2->top == 16) && (BN_num_bits(m2) == 1024))) {
+
+        if (bn_wexpand(rr1, 16) == NULL)
+            goto err;
+        if (bn_wexpand(rr2, 16) == NULL)
+            goto err;
+
+        /*  Ensure that montgomery contexts are initialized */
+        if (in_mont1 != NULL) {
+            mont1 = in_mont1;
+        } else {
+            if ((mont1 = BN_MONT_CTX_new()) == NULL)
+                goto err;
+            if (!BN_MONT_CTX_set(mont1, m1, ctx))
+                goto err;
+        }
+        if (in_mont2 != NULL) {
+            mont2 = in_mont2;
+        } else {
+            if ((mont2 = BN_MONT_CTX_new()) == NULL)
+                goto err;
+            if (!BN_MONT_CTX_set(mont2, m2, ctx))
+                goto err;
+        }
+
+        ret = RSAZ_mod_exp_avx512_x2(rr1->d, a1->d, p1->d, m1->d, mont1->RR.d,
+                                     mont1->n0[0],
+                                     rr2->d, a2->d, p2->d, m2->d, mont2->RR.d,
+                                     mont2->n0[0],
+                                     1024 /* factor bit size */);
+
+        rr1->top = 16;
+        rr1->neg = 0;
+        bn_correct_top(rr1);
+        bn_check_top(rr1);
+
+        rr2->top = 16;
+        rr2->neg = 0;
+        bn_correct_top(rr2);
+        bn_check_top(rr2);
+
+        goto err;
+    }
+#endif
+
+    /* rr1 = a1^p1 mod m1 */
+    ret = BN_mod_exp_mont_consttime(rr1, a1, p1, m1, ctx, in_mont1);
+    /* rr2 = a2^p2 mod m2 */
+    ret &= BN_mod_exp_mont_consttime(rr2, a2, p2, m2, ctx, in_mont2);
+
+#ifdef RSAZ_ENABLED
+err:
+    if (in_mont2 == NULL)
+        BN_MONT_CTX_free(mont2);
+    if (in_mont1 == NULL)
+        BN_MONT_CTX_free(mont1);
+#endif
+
+    return ret;
+}