Crank default salt length of PBE2 to 16 octets

FIPS is currently revising their PBKDF2 recommendations and apparently
they want to require 16 octets.

https://github.com/pyca/cryptography/issues/12949
https://github.com/libressl/portable/issues/1168

ok kenjiro joshua jsing

2 files changed, 13 insertions, 4 deletions

diff --git a/src/lib/libcrypto/asn1/p5_pbe.c b/src/lib/libcrypto/asn1/p5_pbe.c
index 815d6b82b6..668bf5d7c1 100644
--- a/src/lib/libcrypto/asn1/p5_pbe.c
+++ b/src/lib/libcrypto/asn1/p5_pbe.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: p5_pbe.c,v 1.29 2025/05/10 05:54:38 tb Exp $ */
+/* $OpenBSD: p5_pbe.c,v 1.30 2025/05/24 02:57:14 tb Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 1999.
  */
@@ -66,6 +66,9 @@
 #include "err_local.h"
 #include "x509_local.h"
 
+/* RFC 8018, section 6.1 specifies an eight-octet salt for PBES1. */
+#define PKCS5_PBE1_SALT_LEN     8
+
 /* PKCS#5 password based encryption structure */
 
 static const ASN1_TEMPLATE PBEPARAM_seq_tt[] = {
@@ -139,7 +142,7 @@ PKCS5_pbe_set0_algor(X509_ALGOR *algor, int alg, int iter,
                 goto err;
         }
         if (!saltlen)
-                saltlen = PKCS5_SALT_LEN;
+                saltlen = PKCS5_PBE1_SALT_LEN;
         if (!ASN1_STRING_set(pbe->salt, NULL, saltlen)) {
                 ASN1error(ERR_R_MALLOC_FAILURE);
                 goto err;
diff --git a/src/lib/libcrypto/asn1/p5_pbev2.c b/src/lib/libcrypto/asn1/p5_pbev2.c
index 4c096ac5b9..64924d9b38 100644
--- a/src/lib/libcrypto/asn1/p5_pbev2.c
+++ b/src/lib/libcrypto/asn1/p5_pbev2.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: p5_pbev2.c,v 1.37 2025/05/24 02:54:09 tb Exp $ */
+/* $OpenBSD: p5_pbev2.c,v 1.38 2025/05/24 02:57:14 tb Exp $ */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project 1999-2004.
  */
@@ -67,6 +67,12 @@
 #include "evp_local.h"
 #include "x509_local.h"
 
+/*
+ * RFC 8018, sections 6.2 and 4 specify at least 64 bits for PBES2, apparently
+ * FIPS will require at least 128 bits in the future, OpenSSL does that.
+ */
+#define PKCS5_PBE2_SALT_LEN     16
+
 /* PKCS#5 v2.0 password based encryption structures */
 
 static const ASN1_TEMPLATE PBE2PARAM_seq_tt[] = {
@@ -292,7 +298,7 @@ PKCS5_pbkdf2_set(int iter, unsigned char *salt, int saltlen, int prf_nid,
         kdf->salt->type = V_ASN1_OCTET_STRING;
 
         if (!saltlen)
-                saltlen = PKCS5_SALT_LEN;
+                saltlen = PKCS5_PBE2_SALT_LEN;
         if (!(osalt->data = malloc (saltlen)))
                 goto merr;