diff --git a/wolfcrypt/src/pkcs7.c b/wolfcrypt/src/pkcs7.c
index 0c4e159d9..ef09404d3 100755
--- a/wolfcrypt/src/pkcs7.c
+++ b/wolfcrypt/src/pkcs7.c
@@ -3513,27 +3513,18 @@ static int wc_PKCS7_KariGetKeyEncryptionAlgorithmId(WC_PKCS7_KARI* kari,
 }
 
 
-/* remove ASN.1 RecipientEncryptedKeys, return 0 on success, < 0 on error */
-static int wc_PKCS7_KariGetRecipientEncryptedKeys(WC_PKCS7_KARI* kari,
+/* remove ASN.1 SubjectKeyIdentifier, return 0 on success, < 0 on error
+ * if subject key ID matches, recipFound is set to 1 */
+static int wc_PKCS7_KariGetSubjectKeyIdentifier(WC_PKCS7_KARI* kari,
                         byte* pkiMsg, word32 pkiMsgSz, word32* idx,
-                        int* recipFound, byte* encryptedKey,
-                        int* encryptedKeySz)
+                        int* recipFound)
 {
     int length;
     byte subjKeyId[KEYID_SIZE];
 
-    if (kari == NULL || pkiMsg == NULL || idx == NULL ||
-        recipFound == NULL || encryptedKey == NULL)
+    if (kari == NULL || pkiMsg == NULL || idx == NULL || recipFound == NULL)
         return BAD_FUNC_ARG;
 
-    /* remove RecipientEncryptedKeys */
-    if (GetSequence(pkiMsg, idx, &length, pkiMsgSz) < 0)
-        return ASN_PARSE_E;
-
-    /* remove RecipientEncryptedKeys */
-    if (GetSequence(pkiMsg, idx, &length, pkiMsgSz) < 0)
-        return ASN_PARSE_E;
-
     /* remove RecipientKeyIdentifier IMPLICIT [0] */
     if ( (pkiMsgSz > (*idx + 1)) &&
          (pkiMsg[(*idx)++] == (ASN_CONSTRUCTED | ASN_CONTEXT_SPECIFIC | 0)) ) {
@@ -3564,6 +3555,137 @@ static int wc_PKCS7_KariGetRecipientEncryptedKeys(WC_PKCS7_KARI* kari,
         *recipFound = 1;
     }
 
+    return 0;
+}
+
+
+/* remove ASN.1 IssuerAndSerialNumber, return 0 on success, < 0 on error
+ * if issuer and serial number match, recipFound is set to 1 */
+static int wc_PKCS7_KariGetIssuerAndSerialNumber(WC_PKCS7_KARI* kari,
+                        byte* pkiMsg, word32 pkiMsgSz, word32* idx,
+                        int* recipFound)
+{
+    int length, ret;
+    byte issuerHash[KEYID_SIZE];
+#ifdef WOLFSSL_SMALL_STACK
+    mp_int* serial;
+    mp_int* recipSerial;
+#else
+    mp_int  stack_serial;
+    mp_int* serial = &stack_serial;
+
+    mp_int  stack_recipSerial;
+    mp_int* recipSerial = &stack_recipSerial;
+#endif
+
+    /* remove IssuerAndSerialNumber */
+    if (GetSequence(pkiMsg, idx, &length, pkiMsgSz) < 0)
+        return ASN_PARSE_E;
+
+    if (GetNameHash(pkiMsg, idx, issuerHash, pkiMsgSz) < 0)
+        return ASN_PARSE_E;
+
+    /* if we found correct recipient, issuer hashes will match */
+    if (XMEMCMP(issuerHash, kari->decoded->issuerHash, KEYID_SIZE) == 0) {
+        *recipFound = 1;
+    }
+
+#ifdef WOLFSSL_SMALL_STACK
+    serial = (mp_int*)XMALLOC(sizeof(mp_int), NULL,
+                              DYNAMIC_TYPE_TMP_BUFFER);
+    if (serial == NULL)
+        return MEMORY_E;
+
+    recipSerial = (mp_int*)XMALLOC(sizeof(mp_int), NULL,
+                                   DYNAMIC_TYPE_TMP_BUFFER);
+    if (recipSerial == NULL) {
+        XFREE(serial, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        return MEMORY_E;
+    }
+#endif
+
+    if (GetInt(serial, pkiMsg, idx, pkiMsgSz) < 0) {
+#ifdef WOLFSSL_SMALL_STACK
+        XFREE(serial,      NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        XFREE(recipSerial, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+        return ASN_PARSE_E;
+    }
+
+    ret = mp_read_unsigned_bin(recipSerial, kari->decoded->serial,
+                             kari->decoded->serialSz);
+    if (ret != MP_OKAY) {
+        mp_clear(serial);
+        WOLFSSL_MSG("Failed to parse CMS recipient serial number");
+#ifdef WOLFSSL_SMALL_STACK
+        XFREE(serial,      NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        XFREE(recipSerial, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+        return ret;
+    }
+
+    if (mp_cmp(recipSerial, serial) != MP_EQ) {
+        mp_clear(serial);
+        mp_clear(recipSerial);
+        WOLFSSL_MSG("CMS serial number does not match recipient");
+#ifdef WOLFSSL_SMALL_STACK
+        XFREE(serial,      NULL, DYNAMIC_TYPE_TMP_BUFFER);
+        XFREE(recipSerial, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+        return PKCS7_RECIP_E;
+    }
+
+    mp_clear(serial);
+    mp_clear(recipSerial);
+
+#ifdef WOLFSSL_SMALL_STACK
+    XFREE(serial,      NULL, DYNAMIC_TYPE_TMP_BUFFER);
+    XFREE(recipSerial, NULL, DYNAMIC_TYPE_TMP_BUFFER);
+#endif
+
+    return 0;
+}
+
+
+/* remove ASN.1 RecipientEncryptedKeys, return 0 on success, < 0 on error */
+static int wc_PKCS7_KariGetRecipientEncryptedKeys(WC_PKCS7_KARI* kari,
+                        byte* pkiMsg, word32 pkiMsgSz, word32* idx,
+                        int* recipFound, byte* encryptedKey,
+                        int* encryptedKeySz)
+{
+    int length;
+    int ret = 0;
+
+    if (kari == NULL || pkiMsg == NULL || idx == NULL ||
+        recipFound == NULL || encryptedKey == NULL)
+        return BAD_FUNC_ARG;
+
+    /* remove RecipientEncryptedKeys */
+    if (GetSequence(pkiMsg, idx, &length, pkiMsgSz) < 0)
+        return ASN_PARSE_E;
+
+    /* remove RecipientEncryptedKeys */
+    if (GetSequence(pkiMsg, idx, &length, pkiMsgSz) < 0)
+        return ASN_PARSE_E;
+
+    /* KeyAgreeRecipientIdentifier is CHOICE of IssuerAndSerialNumber
+     * or [0] IMMPLICIT RecipientKeyIdentifier */
+    if ( (pkiMsgSz > (*idx + 1)) &&
+         (pkiMsg[*idx] == (ASN_CONSTRUCTED | ASN_CONTEXT_SPECIFIC | 0)) ) {
+
+        /* try to get RecipientKeyIdentifier */
+        ret = wc_PKCS7_KariGetSubjectKeyIdentifier(kari, pkiMsg, pkiMsgSz,
+                                                   idx, recipFound);
+    } else {
+        /* try to get IssuerAndSerialNumber */
+        ret = wc_PKCS7_KariGetIssuerAndSerialNumber(kari, pkiMsg, pkiMsgSz,
+                                                    idx, recipFound);
+    }
+
+    /* if we don't have either option, malformed CMS */
+    if (ret != 0)
+        return ret;
+
     /* remove EncryptedKey */
     if ( (pkiMsgSz > (*idx + 1)) &&
          (pkiMsg[(*idx)++] != ASN_OCTET_STRING) )