diff --git a/config.example.json b/config.example.json
index 41b6c94c..12e166ca 100644
--- a/config.example.json
+++ b/config.example.json
@@ -226,5 +226,9 @@
         }
     }],
     //custom_config: custom configuration for users. This object can be get by the app().getCustomConfig() method. 
-    "custom_config": {}
+    "custom_config": {
+        "realm" : "drogonRealm",
+        "opaque" : "drogonOpaque",
+        "credentials" : [ {"user" : "drogon", "password": "dr0g0n"} ]
+    }
 }
\ No newline at end of file
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index cd1583f0..17554c4c 100755
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -31,6 +31,7 @@ set(simple_example_sources
     simple_example/api_Attachment.cc
     simple_example/api_v1_ApiTest.cc
     simple_example/TimeFilter.cc
+    simple_example/DigestAuthFilter.cc
     simple_example/main.cc)
 
 add_executable(webapp ${simple_example_sources} ${VIEWSRC})
diff --git a/examples/simple_example/DigestAuthFilter.cc b/examples/simple_example/DigestAuthFilter.cc
new file mode 100644
index 00000000..ea08fc57
--- /dev/null
+++ b/examples/simple_example/DigestAuthFilter.cc
@@ -0,0 +1,215 @@
+#include "DigestAuthFilter.h"
+
+#include <drogon/utils/Utilities.h>
+#include <algorithm>
+#include <cctype>
+#include <string>
+
+std::string method2String(HttpMethod m)
+{
+    switch (m)
+    {
+        case Get:
+            return "GET";
+        case Post:
+            return "POST";
+        case Head:
+            return "HEAD";
+        case Put:
+            return "PUT";
+        case Delete:
+            return "DELETE";
+        case Options:
+            return "OPTIONS";
+        default:
+            return "INVALID";
+    }
+}
+
+std::string toLower(const std::string &in)
+{
+    std::string out = in;
+    std::transform(out.begin(), out.end(), out.begin(), [](unsigned char c) {
+        return std::tolower(c);
+    });
+    return out;
+}
+
+bool DigestAuthFilter::isEndOfAttributeName(size_t pos,
+                                            size_t len,
+                                            const char *data)
+{
+    if (pos >= len)
+        return true;
+    if (isspace(static_cast<unsigned char>(data[pos])))
+        return true;
+    // The reason for this complexity is that some attributes may contain
+    // trailing equal signs (like base64 tokens in Negotiate auth headers)
+    if ((pos + 1 < len) && (data[pos] == '=') &&
+        !isspace(static_cast<unsigned char>(data[pos + 1])) &&
+        (data[pos + 1] != '='))
+    {
+        return true;
+    }
+    return false;
+}
+
+void DigestAuthFilter::httpParseAttributes(const char *data,
+                                           size_t len,
+                                           HttpAttributeList &attributes)
+{
+    size_t pos = 0;
+    while (true)
+    {
+        // Skip leading whitespace
+        while ((pos < len) && isspace(static_cast<unsigned char>(data[pos])))
+        {
+            ++pos;
+        }
+
+        // End of attributes?
+        if (pos >= len)
+            return;
+
+        // Find end of attribute name
+        size_t start = pos;
+        while (!isEndOfAttributeName(pos, len, data))
+        {
+            ++pos;
+        }
+
+        HttpAttribute attribute;
+        attribute.first.assign(data + start, data + pos);
+
+        // Attribute has value?
+        if ((pos < len) && (data[pos] == '='))
+        {
+            ++pos;  // Skip '='
+            // Check if quoted value
+            if ((pos < len) && (data[pos] == '"'))
+            {
+                while (++pos < len)
+                {
+                    if (data[pos] == '"')
+                    {
+                        ++pos;
+                        break;
+                    }
+                    if ((data[pos] == '\\') && (pos + 1 < len))
+                        ++pos;
+                    attribute.second.append(1, data[pos]);
+                }
+            }
+            else
+            {
+                while ((pos < len) &&
+                       !isspace(static_cast<unsigned char>(data[pos])) &&
+                       (data[pos] != ','))
+                {
+                    attribute.second.append(1, data[pos++]);
+                }
+            }
+        }
+
+        attributes.push_back(attribute);
+        if ((pos < len) && (data[pos] == ','))
+            ++pos;  // Skip ','
+    }
+}
+
+bool DigestAuthFilter::httpHasAttribute(const HttpAttributeList &attributes,
+                                        const std::string &name,
+                                        std::string *value)
+{
+    for (HttpAttributeList::const_iterator it = attributes.begin();
+         it != attributes.end();
+         ++it)
+    {
+        if (it->first == name)
+        {
+            if (value)
+            {
+                *value = it->second;
+            }
+            return true;
+        }
+    }
+    return false;
+}
+
+DigestAuthFilter::DigestAuthFilter(
+    const std::map<std::string, std::string> &credentials,
+    const std::string &realm,
+    const std::string &opaque)
+    : credentials(credentials), realm(realm), opaque(opaque)
+{
+}
+
+void DigestAuthFilter::doFilter(const HttpRequestPtr &req,
+                                FilterCallback &&cb,
+                                FilterChainCallback &&ccb)
+{
+    if (!req->session())
+    {
+        // no session support by framework,pls enable session
+        auto resp = HttpResponse::newNotFoundResponse();
+        cb(resp);
+        return;
+    }
+
+    auto auth_header = req->getHeader("Authorization");
+    if (!auth_header.empty())
+    {
+        HttpAttributeList att_list;
+        httpParseAttributes(auth_header.c_str(), auth_header.size(), att_list);
+        std::string username, realm, nonce, uri, opaque, response;
+        if (httpHasAttribute(att_list, "username", &username) &&
+            httpHasAttribute(att_list, "realm", &realm) &&
+            httpHasAttribute(att_list, "nonce", &nonce) &&
+            httpHasAttribute(att_list, "uri", &uri) &&
+            httpHasAttribute(att_list, "opaque", &opaque) &&
+            httpHasAttribute(att_list, "response", &response))
+        {
+            if (credentials.find(username) != credentials.end())
+            {
+                std::string A1 =
+                    username + ":" + realm + ":" + credentials.at(username);
+                std::string A2 = method2String(req->getMethod()) + ":" + uri;
+                std::string A1_middle_A2 = toLower(utils::getMd5(A1)) + ":" +
+                                           nonce + ":" +
+                                           toLower(utils::getMd5(A2));
+                std::string calculated_response =
+                    toLower(utils::getMd5(A1_middle_A2));
+                if (response == calculated_response)
+                {
+                    // Passed
+                    ccb();
+                    return;
+                }
+                else
+                {
+                    LOG_DEBUG << "invalid response " << response
+                              << ", calculated " << calculated_response;
+                }
+            }
+            else
+            {
+                LOG_DEBUG << "invalid username " << username;
+            }
+        }
+        else
+        {
+            LOG_DEBUG << "missing attributes in WWW-Authenticate header"
+                      << auth_header;
+        }
+    }
+    // not Passed
+    auto resp = HttpResponse::newHttpResponse();
+    resp->setStatusCode(k401Unauthorized);
+    resp->addHeader("WWW-Authenticate",
+                    " Digest realm=\"" + realm + "\", nonce=\"" +
+                        toLower(utils::getMd5(std::to_string(time(0)))) +
+                        "\", opaque=\"" + opaque + "\"");
+    cb(resp);
+    return;
+}
\ No newline at end of file
diff --git a/examples/simple_example/DigestAuthFilter.h b/examples/simple_example/DigestAuthFilter.h
new file mode 100644
index 00000000..03df6349
--- /dev/null
+++ b/examples/simple_example/DigestAuthFilter.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include <drogon/HttpFilter.h>
+using namespace drogon;
+
+typedef std::pair<std::string, std::string> HttpAttribute;
+typedef std::vector<HttpAttribute> HttpAttributeList;
+typedef std::map<std::string /*username*/, std::string /*password*/>
+    CredentialsMap;
+
+class DigestAuthFilter : public drogon::HttpFilter<DigestAuthFilter, false>
+{
+    const std::map<std::string, std::string> credentials;
+    const std::string realm;
+    const std::string opaque;
+
+    static bool isEndOfAttributeName(size_t pos, size_t len, const char *data);
+    static void httpParseAttributes(const char *data,
+                                    size_t len,
+                                    HttpAttributeList &attributes);
+
+    static bool httpHasAttribute(const HttpAttributeList &attributes,
+                                 const std::string &name,
+                                 std::string *value);
+
+  public:
+    explicit DigestAuthFilter(const CredentialsMap &credentials,
+                              const std::string &realm,
+                              const std::string &opaque);
+    virtual void doFilter(const HttpRequestPtr &req,
+                          FilterCallback &&cb,
+                          FilterChainCallback &&ccb) override;
+};
\ No newline at end of file
diff --git a/examples/simple_example/main.cc b/examples/simple_example/main.cc
index 7e4b8c86..dbb9ef93 100644
--- a/examples/simple_example/main.cc
+++ b/examples/simple_example/main.cc
@@ -1,6 +1,7 @@
 
 #include "CustomCtrl.h"
 #include "CustomHeaderFilter.h"
+#include "DigestAuthFilter.h"
 #include <drogon/drogon.h>
 #include <vector>
 #include <string>
@@ -69,6 +70,22 @@ class B : public DrObjectBase
         callback(res);
     }
 };
+
+class C : public drogon::HttpController<C>
+{
+  public:
+    METHOD_LIST_BEGIN
+    ADD_METHOD_TO(C::priv, "/priv/resource", Get, "DigestAuthFilter");
+    METHOD_LIST_END
+    void priv(const HttpRequestPtr &req,
+              std::function<void(const HttpResponsePtr &)> &&callback) const
+    {
+        auto resp = HttpResponse::newHttpResponse();
+        resp->setBody("<P>private content, only for authenticated users</P>");
+        callback(resp);
+    }
+};
+
 namespace api
 {
 namespace v1
@@ -192,6 +209,9 @@ int main()
     app().setDocumentRoot("./");
     app().enableSession(60);
 
+    std::map<std::string, std::string> config_credentials;
+    std::string realm("drogonRealm");
+    std::string opaque("drogonOpaque");
     // Load configuration
     app().loadConfigFile("config.example.json");
     auto &json = app().getCustomConfig();
@@ -199,6 +219,27 @@ int main()
     {
         std::cout << "empty custom config!" << std::endl;
     }
+    else
+    {
+        if (!json["realm"].empty())
+        {
+            realm = json["realm"].asString();
+        }
+        if (!json["opaque"].empty())
+        {
+            opaque = json["opaque"].asString();
+        }
+        for (auto &&i : json["credentials"])
+        {
+            config_credentials[i["user"].asString()] = i["password"].asString();
+        }
+    }
+
+    // Install Digest Authentication Filter using custom config credentials,
+    // used by C HttpController (/C/priv/resource)
+    auto auth_filter =
+        std::make_shared<DigestAuthFilter>(config_credentials, realm, opaque);
+    app().registerFilter(auth_filter);
 
     // Install custom controller
     auto ctrlPtr = std::make_shared<CustomCtrl>("Hi");
diff --git a/lib/inc/drogon/utils/Utilities.h b/lib/inc/drogon/utils/Utilities.h
index ec1747d2..b7075636 100644
--- a/lib/inc/drogon/utils/Utilities.h
+++ b/lib/inc/drogon/utils/Utilities.h
@@ -97,6 +97,9 @@ inline std::string urlDecode(const string_view &szToDecode)
 std::string urlEncode(const std::string &);
 std::string urlEncodeComponent(const std::string &);
 
+/// Get the MD5 digest of a string.
+std::string getMd5(const std::string &originalString);
+
 /// Commpress or decompress data using gzip lib.
 /**
  * @param data the input data
diff --git a/lib/src/MultiPart.cc b/lib/src/MultiPart.cc
index 77bc6337..ff90e1dc 100644
--- a/lib/src/MultiPart.cc
+++ b/lib/src/MultiPart.cc
@@ -18,11 +18,6 @@
 #include <drogon/MultiPart.h>
 #include <drogon/utils/Utilities.h>
 #include <drogon/config.h>
-#ifdef OpenSSL_FOUND
-#include <openssl/md5.h>
-#else
-#include "ssl_funcs/Md5.h"
-#endif
 #include <algorithm>
 #include <fcntl.h>
 #include <fstream>
@@ -226,14 +221,5 @@ int HttpFile::saveTo(const std::string &pathAndFilename) const
 }
 std::string HttpFile::getMd5() const
 {
-#ifdef OpenSSL_FOUND
-    MD5_CTX c;
-    unsigned char md5[16] = {0};
-    MD5_Init(&c);
-    MD5_Update(&c, fileContent_.c_str(), fileContent_.size());
-    MD5_Final(md5, &c);
-    return utils::binaryStringToHex(md5, 16);
-#else
-    return Md5Encode::encode(fileContent_);
-#endif
+    return utils::getMd5(fileContent_);
 }
diff --git a/lib/src/Utilities.cc b/lib/src/Utilities.cc
index 18696358..e5819ce1 100644
--- a/lib/src/Utilities.cc
+++ b/lib/src/Utilities.cc
@@ -14,6 +14,12 @@
 
 #include <drogon/utils/Utilities.h>
 #include <trantor/utils/Logger.h>
+#include <drogon/config.h>
+#ifdef OpenSSL_FOUND
+#include <openssl/md5.h>
+#else
+#include "ssl_funcs/Md5.h"
+#endif
 #ifdef USE_BROTLI
 #include <brotli/decode.h>
 #include <brotli/encode.h>
@@ -1138,5 +1144,19 @@ std::string brotliDecompress(const char *data, const size_t ndata)
 }
 #endif
 
+std::string getMd5(const std::string &originalString)
+{
+#ifdef OpenSSL_FOUND
+    MD5_CTX c;
+    unsigned char md5[16] = {0};
+    MD5_Init(&c);
+    MD5_Update(&c, originalString.c_str(), originalString.size());
+    MD5_Final(md5, &c);
+    return utils::binaryStringToHex(md5, 16);
+#else
+    return Md5Encode::encode(originalString);
+#endif
+}
+
 }  // namespace utils
 }  // namespace drogon
diff --git a/unittest/CMakeLists.txt b/unittest/CMakeLists.txt
index 55adb082..abda59d3 100644
--- a/unittest/CMakeLists.txt
+++ b/unittest/CMakeLists.txt
@@ -1,7 +1,7 @@
 add_executable(drogon_msgbuffer_unittest MsgBufferUnittest.cpp)
 add_executable(drobject_unittest DrObjectUnittest.cpp)
 add_executable(gzip_unittest GzipUnittest.cpp)
-add_executable(md5_unittest MD5Unittest.cpp ../lib/src/ssl_funcs/Md5.cc)
+add_executable(md5_unittest MD5Unittest.cpp)
 add_executable(sha1_unittest SHA1Unittest.cpp ../lib/src/ssl_funcs/Sha1.cc)
 add_executable(ostringstream_unittest OStringStreamUnitttest.cpp)
 add_executable(base64_unittest Base64Unittest.cpp)
diff --git a/unittest/MD5Unittest.cpp b/unittest/MD5Unittest.cpp
index cafd2123..06dd2bac 100644
--- a/unittest/MD5Unittest.cpp
+++ b/unittest/MD5Unittest.cpp
@@ -1,14 +1,15 @@
-#include "../lib/src/ssl_funcs/Md5.h"
+#include <drogon/utils/Utilities.h>
 #include <gtest/gtest.h>
 #include <string>
 
 TEST(Md5Test, md5)
 {
-    // EXPECT_EQ(Md5Encode::encode("123456789012345678901234567890123456789012345"
-    //                             "678901234567890123456789012345678901234567890"
-    //                             "1234567890"),
-    //           "49CB3608E2B33FAD6B65DF8CB8F49668");
-    EXPECT_EQ(Md5Encode::encode("1"), "C4CA4238A0B923820DCC509A6F75849B");
+    EXPECT_EQ(drogon::utils::getMd5(
+                  "123456789012345678901234567890123456789012345"
+                  "678901234567890123456789012345678901234567890"
+                  "1234567890"),
+              "49CB3608E2B33FAD6B65DF8CB8F49668");
+    EXPECT_EQ(drogon::utils::getMd5("1"), "C4CA4238A0B923820DCC509A6F75849B");
 }
 
 int main(int argc, char **argv)