diff --git a/tests/api.c b/tests/api.c
index 61d95ee635..ef7b785771 100644
--- a/tests/api.c
+++ b/tests/api.c
@@ -23340,7 +23340,11 @@ static int test_wc_Ed25519PublicKeyToDer(void)
         ExpectIntEQ(wc_ed25519_init(&key), 0);
         ExpectIntEQ(wc_InitRng(&rng), 0);
         ExpectIntEQ(wc_ed25519_make_key(&rng, ED25519_KEY_SIZE, &key), 0);
-        ExpectIntGT(wc_Ed25519PublicKeyToDer(&key, derBuf, 1024, 1), 0);
+        /* length only */
+        ExpectIntGT(wc_Ed25519PublicKeyToDer(&key, NULL, 0, 0), 0);
+        ExpectIntGT(wc_Ed25519PublicKeyToDer(&key, NULL, 0, 1), 0);
+        ExpectIntGT(wc_Ed25519PublicKeyToDer(&key, derBuf,
+                    (word32)sizeof(derBuf), 1), 0);
 
         DoExpectIntEQ(wc_FreeRng(&rng), 0);
         wc_ed25519_free(&key);
@@ -24233,8 +24237,11 @@ static int test_wc_Ed448PublicKeyToDer(void)
         ExpectIntEQ(wc_ed448_init(&key), 0);
         ExpectIntEQ(wc_InitRng(&rng), 0);
         ExpectIntEQ(wc_ed448_make_key(&rng, ED448_KEY_SIZE, &key), 0);
-
-        ExpectIntGT(wc_Ed448PublicKeyToDer(&key, derBuf, 1024, 1), 0);
+        /* length only */
+        ExpectIntGT(wc_Ed448PublicKeyToDer(&key, NULL, 0, 0), 0);
+        ExpectIntGT(wc_Ed448PublicKeyToDer(&key, NULL, 0, 1), 0);
+        ExpectIntGT(wc_Ed448PublicKeyToDer(&key, derBuf,
+                    (word32)sizeof(derBuf), 1), 0);
 
         DoExpectIntEQ(wc_FreeRng(&rng), 0);
         wc_ed448_free(&key);
@@ -26860,9 +26867,10 @@ static int test_wc_Ed25519KeyToDer(void)
     /* Bad Cases */
     ExpectIntEQ(wc_Ed25519KeyToDer(NULL, NULL, 0), BAD_FUNC_ARG);
     ExpectIntEQ(wc_Ed25519KeyToDer(NULL, output, inLen), BAD_FUNC_ARG);
-    ExpectIntEQ(wc_Ed25519KeyToDer(&ed25519Key, output, 0), BAD_FUNC_ARG);
+    ExpectIntEQ(wc_Ed25519KeyToDer(&ed25519Key, output, 0), BUFFER_E);
     /* Good Cases */
     /* length only */
+    ExpectIntGT(wc_Ed25519KeyToDer(&ed25519Key, NULL, 0), 0);
     ExpectIntGT(wc_Ed25519KeyToDer(&ed25519Key, NULL, inLen), 0);
     ExpectIntGT(wc_Ed25519KeyToDer(&ed25519Key, output, inLen), 0);
 
@@ -26898,10 +26906,10 @@ static int test_wc_Ed25519PrivateKeyToDer(void)
     ExpectIntEQ(wc_Ed25519PrivateKeyToDer(NULL, NULL, 0), BAD_FUNC_ARG);
     ExpectIntEQ(wc_Ed25519PrivateKeyToDer(NULL, output, inLen), BAD_FUNC_ARG);
     ExpectIntEQ(wc_Ed25519PrivateKeyToDer(&ed25519PrivKey, output, 0),
-        BAD_FUNC_ARG);
+        BUFFER_E);
     /* Good Cases */
     /* length only */
-    ExpectIntGT(wc_Ed25519PrivateKeyToDer(&ed25519PrivKey, NULL, inLen), 0);
+    ExpectIntGT(wc_Ed25519PrivateKeyToDer(&ed25519PrivKey, NULL, 0), 0);
     ExpectIntGT(wc_Ed25519PrivateKeyToDer(&ed25519PrivKey, output, inLen), 0);
 
     DoExpectIntEQ(wc_FreeRng(&rng), 0);
@@ -26934,10 +26942,10 @@ static int test_wc_Ed448KeyToDer(void)
     /* Bad Cases */
     ExpectIntEQ(wc_Ed448KeyToDer(NULL, NULL, 0), BAD_FUNC_ARG);
     ExpectIntEQ(wc_Ed448KeyToDer(NULL, output, inLen), BAD_FUNC_ARG);
-    ExpectIntEQ(wc_Ed448KeyToDer(&ed448Key, output, 0), BAD_FUNC_ARG);
+    ExpectIntEQ(wc_Ed448KeyToDer(&ed448Key, output, 0), BUFFER_E);
     /* Good Cases */
     /* length only */
-    ExpectIntGT(wc_Ed448KeyToDer(&ed448Key, NULL, inLen), 0);
+    ExpectIntGT(wc_Ed448KeyToDer(&ed448Key, NULL, 0), 0);
     ExpectIntGT(wc_Ed448KeyToDer(&ed448Key, output, inLen), 0);
 
     DoExpectIntEQ(wc_FreeRng(&rng), 0);
@@ -26972,10 +26980,10 @@ static int test_wc_Ed448PrivateKeyToDer(void)
     ExpectIntEQ(wc_Ed448PrivateKeyToDer(NULL, NULL, 0), BAD_FUNC_ARG);
     ExpectIntEQ(wc_Ed448PrivateKeyToDer(NULL, output, inLen), BAD_FUNC_ARG);
     ExpectIntEQ(wc_Ed448PrivateKeyToDer(&ed448PrivKey, output, 0),
-        BAD_FUNC_ARG);
+        BUFFER_E);
     /* Good cases */
     /* length only */
-    ExpectIntGT(wc_Ed448PrivateKeyToDer(&ed448PrivKey, NULL, inLen), 0);
+    ExpectIntGT(wc_Ed448PrivateKeyToDer(&ed448PrivKey, NULL, 0), 0);
     ExpectIntGT(wc_Ed448PrivateKeyToDer(&ed448PrivKey, output, inLen), 0);
 
     DoExpectIntEQ(wc_FreeRng(&rng), 0);
@@ -27010,10 +27018,10 @@ static int test_wc_Curve448PrivateKeyToDer(void)
     ExpectIntEQ(wc_Curve448PrivateKeyToDer(NULL, NULL, 0), BAD_FUNC_ARG);
     ExpectIntEQ(wc_Curve448PrivateKeyToDer(NULL, output, inLen), BAD_FUNC_ARG);
     ExpectIntEQ(wc_Curve448PrivateKeyToDer(&curve448PrivKey, output, 0),
-        BAD_FUNC_ARG);
+        BUFFER_E);
     /* Good cases */
     /* length only */
-    ExpectIntGT(wc_Curve448PrivateKeyToDer(&curve448PrivKey, NULL, inLen), 0);
+    ExpectIntGT(wc_Curve448PrivateKeyToDer(&curve448PrivKey, NULL, 0), 0);
     ExpectIntGT(wc_Curve448PrivateKeyToDer(&curve448PrivKey, output, inLen), 0);
 
     /* Bad Cases */
@@ -27025,8 +27033,8 @@ static int test_wc_Curve448PrivateKeyToDer(void)
         BUFFER_E);
     /* Good cases */
     /* length only */
-    ExpectIntGT(wc_Curve448PublicKeyToDer(&curve448PrivKey, NULL, inLen, 0), 0);
-    ExpectIntGT(wc_Curve448PublicKeyToDer(&curve448PrivKey, NULL, inLen, 1), 0);
+    ExpectIntGT(wc_Curve448PublicKeyToDer(&curve448PrivKey, NULL, 0, 0), 0);
+    ExpectIntGT(wc_Curve448PublicKeyToDer(&curve448PrivKey, NULL, 0, 1), 0);
     ExpectIntGT(wc_Curve448PublicKeyToDer(&curve448PrivKey, output, inLen, 0), 0);
     ExpectIntGT(wc_Curve448PublicKeyToDer(&curve448PrivKey, output, inLen, 1), 0);
 
diff --git a/wolfcrypt/src/asn.c b/wolfcrypt/src/asn.c
index 16d773c5e7..b3ad9fd675 100644
--- a/wolfcrypt/src/asn.c
+++ b/wolfcrypt/src/asn.c
@@ -11994,9 +11994,13 @@ int SetAsymKeyDerPublic(const byte* pubKey, word32 pubKeyLen,
     DECL_ASNSETDATA(dataASN, edPubKeyASN_Length);
 #endif
 
-    if (pubKey == NULL) {
+    /* validate parameters */
+    if (pubKey == NULL){
         return BAD_FUNC_ARG;
     }
+    if (output != NULL && outLen == 0) {
+        return BUFFER_E;
+    }
 
 #ifndef WOLFSSL_ASN_TEMPLATE
     /* calculate size */
@@ -35337,10 +35341,13 @@ int SetAsymKeyDer(const byte* privKey, word32 privKeyLen,
     int sz;
 #endif
 
-    /* Validate parameters. */
-    if (privKey == NULL || outLen == 0) {
+    /* validate parameters */
+    if (privKey == NULL) {
         return BAD_FUNC_ARG;
     }
+    if (output != NULL && outLen == 0) {
+        return BUFFER_E;
+    }
 
 #ifndef WOLFSSL_ASN_TEMPLATE
     /* calculate size */
@@ -35498,7 +35505,7 @@ int wc_Curve25519PublicKeyToDer(curve25519_key* key, byte* output, word32 inLen,
     byte   pubKey[CURVE25519_PUB_KEY_SIZE];
     word32 pubKeyLen = (word32)sizeof(pubKey);
 
-    if (key == NULL || output == NULL) {
+    if (key == NULL) {
         return BAD_FUNC_ARG;
     }