--- /dev/null
+/*
+ * Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License"). You may not use
+ * this file except in compliance with the License. You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/core.h>
+#include <openssl/core_names.h>
+#include <openssl/evp.h>
+#include <openssl/obj_mac.h>
+#include "internal/nelem.h"
+#include "crypto/rsa.h"
+
+static int meth2nid(const void *meth,
+ int (*meth_is_a)(const void *meth, const char *name),
+ const OSSL_ITEM *items, size_t items_n)
+{
+ size_t i;
+
+ if (meth != NULL)
+ for (i = 0; i < items_n; i++)
+ if (meth_is_a(meth, items[i].ptr))
+ return (int)items[i].id;
+ return NID_undef;
+}
+
+static const char *nid2name(int meth, const OSSL_ITEM *items, size_t items_n)
+{
+ size_t i;
+
+ for (i = 0; i < items_n; i++)
+ if (meth == (int)items[i].id)
+ return items[i].ptr;
+ return NULL;
+}
+
+/*
+ * The list of permitted hash functions are taken from
+ * https://tools.ietf.org/html/rfc8017#appendix-A.2.1:
+ *
+ * OAEP-PSSDigestAlgorithms ALGORITHM-IDENTIFIER ::= {
+ * { OID id-sha1 PARAMETERS NULL }|
+ * { OID id-sha224 PARAMETERS NULL }|
+ * { OID id-sha256 PARAMETERS NULL }|
+ * { OID id-sha384 PARAMETERS NULL }|
+ * { OID id-sha512 PARAMETERS NULL }|
+ * { OID id-sha512-224 PARAMETERS NULL }|
+ * { OID id-sha512-256 PARAMETERS NULL },
+ * ... -- Allows for future expansion --
+ * }
+ */
+static const OSSL_ITEM oaeppss_name_nid_map[] = {
+ { NID_sha1, OSSL_DIGEST_NAME_SHA1 },
+ { NID_sha224, OSSL_DIGEST_NAME_SHA2_224 },
+ { NID_sha256, OSSL_DIGEST_NAME_SHA2_256 },
+ { NID_sha384, OSSL_DIGEST_NAME_SHA2_384 },
+ { NID_sha512, OSSL_DIGEST_NAME_SHA2_512 },
+ { NID_sha512_224, OSSL_DIGEST_NAME_SHA2_512_224 },
+ { NID_sha512_256, OSSL_DIGEST_NAME_SHA2_512_256 },
+};
+
+static int md_is_a(const void *md, const char *name)
+{
+ return EVP_MD_is_a(md, name);
+}
+
+int rsa_oaeppss_md2nid(const EVP_MD *md)
+{
+ return meth2nid(md, md_is_a,
+ oaeppss_name_nid_map, OSSL_NELEM(oaeppss_name_nid_map));
+}
+
+const char *rsa_oaeppss_nid2name(int md)
+{
+ return nid2name(md, oaeppss_name_nid_map, OSSL_NELEM(oaeppss_name_nid_map));
+}
+
+const char *rsa_mgf_nid2name(int mgf)
+{
+ if (mgf == NID_mgf1)
+ return SN_mgf1;
+ return NULL;
+}