RSA Keygen update - When using the default provider fallback to default multiprime...

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18429)

diff --git a/crypto/rsa/rsa_gen.c b/crypto/rsa/rsa_gen.c
index ac64483e6a2ffe3057e4976cd65caa76b60bffd8..4a3387f19e5f70b8a9021196c006c51c3b057dc7 100644 (file)
--- a/crypto/rsa/rsa_gen.c
+++ b/crypto/rsa/rsa_gen.c
@@ -426,20 +426,22 @@ static int rsa_keygen(OSSL_LIB_CTX *libctx, RSA *rsa, int bits, int primes,
 {
     int ok = 0;
 
+#ifdef FIPS_MODULE
+    ok = ossl_rsa_sp800_56b_generate_key(rsa, bits, e_value, cb);
+    pairwise_test = 1; /* FIPS MODE needs to always run the pairwise test */
+#else
     /*
-     * Only multi-prime keys or insecure keys with a small key length will use
-     * the older rsa_multiprime_keygen().
+     * Only multi-prime keys or insecure keys with a small key length or a
+     * public exponent <= 2^16 will use the older rsa_multiprime_keygen().
      */
-    if (primes == 2 && bits >= 2048)
+    if (primes == 2
+            && bits >= 2048
+            && (e_value == NULL || BN_num_bits(e_value) > 16))
         ok = ossl_rsa_sp800_56b_generate_key(rsa, bits, e_value, cb);
-#ifndef FIPS_MODULE
     else
         ok = rsa_multiprime_keygen(rsa, bits, primes, e_value, cb);
 #endif /* FIPS_MODULE */
 
-#ifdef FIPS_MODULE
-    pairwise_test = 1; /* FIPS MODE needs to always run the pairwise test */
-#endif
     if (pairwise_test && ok > 0) {
         OSSL_CALLBACK *stcb = NULL;
         void *stcbarg = NULL;