diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index c98c158..bbd07a9 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -93,7 +93,7 @@ static void public_key_destroy(void *payload0, void *payload3)
 					     pkey->pkey_algo);
 			} else {
 				if (!hash_algo)
-					return -EINVAL;
+					hash_algo = "none";
 				n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
 					     "pkcs1(%s,%s)",
 					     pkey->pkey_algo, hash_algo);
diff --git a/crypto/rsassa-pkcs1.c b/crypto/rsassa-pkcs1.c
index 9c28f1c..4d077fc9 100644
--- a/crypto/rsassa-pkcs1.c
+++ b/crypto/rsassa-pkcs1.c
@@ -27,6 +27,8 @@
  * https://www.rfc-editor.org/rfc/rfc9580#table-24
  */
 
+static const u8 hash_prefix_none[] = { };
+
 static const u8 hash_prefix_md5[] = {
 	0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,	  /* SEQUENCE (SEQUENCE (OID */
 	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05,	/*	<algorithm>, */
@@ -93,6 +95,7 @@
 	size_t		size;
 } hash_prefixes[] = {
 #define _(X) { #X, hash_prefix_##X, sizeof(hash_prefix_##X) }
+	_(none),
 	_(md5),
 	_(sha1),
 	_(rmd160),
@@ -119,9 +122,18 @@ static const struct hash_prefix *rsassa_pkcs1_find_hash_prefix(const char *name)
 	return NULL;
 }
 
-static unsigned int rsassa_pkcs1_hash_len(const struct hash_prefix *p)
+static bool rsassa_pkcs1_invalid_hash_len(unsigned int len,
+					  const struct hash_prefix *p)
 {
 	/*
+	 * Legacy protocols such as TLS 1.1 or earlier and IKE version 1
+	 * do not prepend a Full Hash Prefix to the hash.  In that case,
+	 * the size of the Full Hash Prefix is zero.
+	 */
+	if (p->data == hash_prefix_none)
+		return false;
+
+	/*
 	 * The final byte of the Full Hash Prefix encodes the hash length.
 	 *
 	 * This needs to be revisited should hash algorithms with more than
@@ -130,7 +142,7 @@ static unsigned int rsassa_pkcs1_hash_len(const struct hash_prefix *p)
 	 */
 	static_assert(HASH_MAX_DIGESTSIZE <= 127);
 
-	return p->data[p->size - 1];
+	return len != p->data[p->size - 1];
 }
 
 struct rsassa_pkcs1_ctx {
@@ -167,7 +179,7 @@ static int rsassa_pkcs1_sign(struct crypto_sig *tfm,
 	if (dlen < ctx->key_size)
 		return -EOVERFLOW;
 
-	if (slen != rsassa_pkcs1_hash_len(hash_prefix))
+	if (rsassa_pkcs1_invalid_hash_len(slen, hash_prefix))
 		return -EINVAL;
 
 	if (slen + hash_prefix->size > ctx->key_size - 11)
@@ -237,7 +249,7 @@ static int rsassa_pkcs1_verify(struct crypto_sig *tfm,
 	/* RFC 8017 sec 8.2.2 step 1 - length checking */
 	if (!ctx->key_size ||
 	    slen != ctx->key_size ||
-	    dlen != rsassa_pkcs1_hash_len(hash_prefix))
+	    rsassa_pkcs1_invalid_hash_len(dlen, hash_prefix))
 		return -EINVAL;
 
 	/* RFC 8017 sec 8.2.2 step 2 - RSA verification */
diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index 7d768f0..86126be 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -5540,6 +5540,12 @@ static int alg_test_null(const struct alg_test_desc *desc,
 			.cipher = __VECS(fcrypt_pcbc_tv_template)
 		}
 	}, {
+		.alg = "pkcs1(rsa,none)",
+		.test = alg_test_sig,
+		.suite = {
+			.sig = __VECS(pkcs1_rsa_none_tv_template)
+		}
+	}, {
 		.alg = "pkcs1(rsa,sha224)",
 		.test = alg_test_null,
 		.fips_allowed = 1,
diff --git a/crypto/testmgr.h b/crypto/testmgr.h
index 55aae18..430d33d 100644
--- a/crypto/testmgr.h
+++ b/crypto/testmgr.h
@@ -1983,6 +1983,61 @@ struct kpp_testvec {
 };
 
 /*
+ * PKCS#1 RSA test vectors for hash algorithm "none"
+ * (i.e. the hash in "m" is not prepended by a Full Hash Prefix)
+ *
+ * Obtained from:
+ * https://vcsjones.dev/sometimes-valid-rsa-dotnet/
+ * https://gist.github.com/vcsjones/ab4c2327b53ed018eada76b75ef4fd99
+ */
+static const struct sig_testvec pkcs1_rsa_none_tv_template[] = {
+	{
+	.key =
+	"\x30\x82\x01\x0a\x02\x82\x01\x01\x00\xa2\x63\x0b\x39\x44\xb8\xbb"
+	"\x23\xa7\x44\x49\xbb\x0e\xff\xa1\xf0\x61\x0a\x53\x93\xb0\x98\xdb"
+	"\xad\x2c\x0f\x4a\xc5\x6e\xff\x86\x3c\x53\x55\x0f\x15\xce\x04\x3f"
+	"\x2b\xfd\xa9\x96\x96\xd9\xbe\x61\x79\x0b\x5b\xc9\x4c\x86\x76\xe5"
+	"\xe0\x43\x4b\x22\x95\xee\xc2\x2b\x43\xc1\x9f\xd8\x68\xb4\x8e\x40"
+	"\x4f\xee\x85\x38\xb9\x11\xc5\x23\xf2\x64\x58\xf0\x15\x32\x6f\x4e"
+	"\x57\xa1\xae\x88\xa4\x02\xd7\x2a\x1e\xcd\x4b\xe1\xdd\x63\xd5\x17"
+	"\x89\x32\x5b\xb0\x5e\x99\x5a\xa8\x9d\x28\x50\x0e\x17\xee\x96\xdb"
+	"\x61\x3b\x45\x51\x1d\xcf\x12\x56\x0b\x92\x47\xfc\xab\xae\xf6\x66"
+	"\x3d\x47\xac\x70\x72\xe7\x92\xe7\x5f\xcd\x10\xb9\xc4\x83\x64\x94"
+	"\x19\xbd\x25\x80\xe1\xe8\xd2\x22\xa5\xd0\xba\x02\x7a\xa1\x77\x93"
+	"\x5b\x65\xc3\xee\x17\x74\xbc\x41\x86\x2a\xdc\x08\x4c\x8c\x92\x8c"
+	"\x91\x2d\x9e\x77\x44\x1f\x68\xd6\xa8\x74\x77\xdb\x0e\x5b\x32\x8b"
+	"\x56\x8b\x33\xbd\xd9\x63\xc8\x49\x9d\x3a\xc5\xc5\xea\x33\x0b\xd2"
+	"\xf1\xa3\x1b\xf4\x8b\xbe\xd9\xb3\x57\x8b\x3b\xde\x04\xa7\x7a\x22"
+	"\xb2\x24\xae\x2e\xc7\x70\xc5\xbe\x4e\x83\x26\x08\xfb\x0b\xbd\xa9"
+	"\x4f\x99\x08\xe1\x10\x28\x72\xaa\xcd\x02\x03\x01\x00\x01",
+	.key_len = 270,
+	.m =
+	"\x68\xb4\xf9\x26\x34\x31\x25\xdd\x26\x50\x13\x68\xc1\x99\x26\x71"
+	"\x19\xa2\xde\x81",
+	.m_size = 20,
+	.c =
+	"\x6a\xdb\x39\xe5\x63\xb3\x25\xde\x58\xca\xc3\xf1\x36\x9c\x0b\x36"
+	"\xb7\xd6\x69\xf9\xba\xa6\x68\x14\x8c\x24\x52\xd3\x25\xa5\xf3\xad"
+	"\xc9\x47\x44\xde\x06\xd8\x0f\x56\xca\x2d\xfb\x0f\xe9\x99\xe2\x9d"
+	"\x8a\xe8\x7f\xfb\x9a\x99\x96\xf1\x2c\x4a\xe4\xc0\xae\x4d\x29\x47"
+	"\x38\x96\x51\x2f\x6d\x8e\xb8\x88\xbd\x1a\x0a\x70\xbc\x23\x38\x67"
+	"\x62\x22\x01\x23\x71\xe5\xbb\x95\xea\x6b\x8d\x31\x62\xbf\xf0\xc4"
+	"\xb9\x46\xd6\x67\xfc\x4c\xe6\x1f\xd6\x5d\xf7\xa9\xad\x3a\xf1\xbf"
+	"\xa2\xf9\x66\xde\xb6\x8e\xec\x8f\x81\x8d\x1e\x3a\x12\x27\x6a\xfc"
+	"\xae\x92\x9f\xc3\x87\xc3\xba\x8d\x04\xb8\x8f\x0f\x61\x68\x9a\x96"
+	"\x2c\x80\x2c\x32\x40\xde\x9d\xb9\x9b\xe2\xe4\x45\x2e\x91\x47\x5c"
+	"\x47\xa4\x9d\x02\x57\x59\xf7\x75\x5d\x5f\x32\x82\x75\x5d\xe5\x78"
+	"\xc9\x19\x61\x46\x06\x9d\xa5\x1d\xd6\x32\x48\x9a\xdb\x09\x29\x81"
+	"\x14\x2e\xf0\x27\xe9\x37\x13\x74\xec\xa5\xcd\x67\x6b\x19\xf6\x88"
+	"\xf0\xc2\x8b\xa8\x7f\x2f\x76\x5a\x3e\x0c\x47\x5d\xe8\x82\x50\x27"
+	"\x40\xce\x27\x41\x45\xa0\xcf\xaa\x2f\xd3\xad\x3c\xbf\x73\xff\x93"
+	"\xe3\x78\x49\xd9\xa9\x78\x22\x81\x9a\xe5\xe2\x94\xe9\x40\xab\xf1",
+	.c_size = 256,
+	.public_key_vec = true,
+	},
+};
+
+/*
  * PKCS#1 RSA test vectors. Obtained from CAVS testing.
  */
 static const struct sig_testvec pkcs1_rsa_tv_template[] = {
