diff --git a/src/framework/CMakeLists.txt b/src/framework/CMakeLists.txt
index f5f64e0e..b08a1402 100644
--- a/src/framework/CMakeLists.txt
+++ b/src/framework/CMakeLists.txt
@@ -219,14 +219,12 @@ endif()
 message(STATUS "LuaJIT: " ${LUAJIT})
 
 find_package(PhysFS REQUIRED)
-find_package(OpenSSL REQUIRED)
 find_package(ZLIB REQUIRED)
 
 set(framework_LIBRARIES ${framework_LIBRARIES}
     ${Boost_LIBRARIES}
     ${LUA_LIBRARY}
     ${PHYSFS_LIBRARY}
-    ${OPENSSL_LIBRARIES}
     ${ZLIB_LIBRARY}
 )
 
@@ -234,10 +232,21 @@ set(framework_INCLUDE_DIRS ${framework_INCLUDE_DIRS}
     ${Boost_INCLUDE_DIRS}
     ${LUA_INCLUDE_DIR}
     ${PHYSFS_INCLUDE_DIR}
-    ${OPENSSL_INCLUDE_DIR}
     ${framework_INCLUDE_DIRS}
 )
 
+find_package(OpenSSL QUIET)
+
+if(NOT OPENSSL_FOUND)
+    find_package(GMP REQUIRED)
+    set(framework_LIBRARIES ${framework_LIBRARIES} ${GMP_LIBRARY})
+    set(framework_INCLUDE_DIRS ${framework_INCLUDE_DIRS} ${GMP_INCLUDE_DIR})
+    set(framework_DEFINITIONS ${framework_DEFINITIONS} -DUSE_GMP)
+else()
+    set(framework_LIBRARIES ${framework_LIBRARIES} ${OPENSSL_LIBRARIES})
+    set(framework_INCLUDE_DIRS ${framework_INCLUDE_DIRS} ${OPENSSL_INCLUDE_DIR})
+endif()
+
 if(CMAKE_BUILD_TYPE STREQUAL "Debug" OR CMAKE_BUILD_TYPE STREQUAL "RelWithDebInfo")
     message(STATUS "Debug information: ON")
 else()
@@ -550,4 +559,3 @@ endif()
 
 include_directories(${framework_INCLUDE_DIRS})
 add_definitions(${framework_DEFINITIONS})
-
diff --git a/src/framework/luafunctions.cpp b/src/framework/luafunctions.cpp
index bd477b02..eb4b0bd1 100644
--- a/src/framework/luafunctions.cpp
+++ b/src/framework/luafunctions.cpp
@@ -120,12 +120,8 @@ void Application::registerLuaFunctions()
     g_lua.bindSingletonFunction("g_crypt", "getMachineUUID", &Crypt::getMachineUUID, &g_crypt);
     g_lua.bindSingletonFunction("g_crypt", "encrypt", &Crypt::encrypt, &g_crypt);
     g_lua.bindSingletonFunction("g_crypt", "decrypt", &Crypt::decrypt, &g_crypt);
-    g_lua.bindSingletonFunction("g_crypt", "sha1Encode", &Crypt::sha1Encode, &g_crypt);
-    g_lua.bindSingletonFunction("g_crypt", "md5Encode", &Crypt::md5Encode, &g_crypt);
-    g_lua.bindSingletonFunction("g_crypt", "rsaGenerateKey", &Crypt::rsaGenerateKey, &g_crypt);
     g_lua.bindSingletonFunction("g_crypt", "rsaSetPublicKey", &Crypt::rsaSetPublicKey, &g_crypt);
     g_lua.bindSingletonFunction("g_crypt", "rsaSetPrivateKey", &Crypt::rsaSetPrivateKey, &g_crypt);
-    g_lua.bindSingletonFunction("g_crypt", "rsaCheckKey", &Crypt::rsaCheckKey, &g_crypt);
     g_lua.bindSingletonFunction("g_crypt", "rsaGetSize", &Crypt::rsaGetSize, &g_crypt);
 
     // Clock
diff --git a/src/framework/util/crypt.cpp b/src/framework/util/crypt.cpp
index 1833a0a0..173c64d4 100644
--- a/src/framework/util/crypt.cpp
+++ b/src/framework/util/crypt.cpp
@@ -32,11 +32,11 @@
 
 #include <boost/functional/hash.hpp>
 
+#ifndef USE_GMP
 #include <openssl/rsa.h>
-#include <openssl/sha.h>
-#include <openssl/md5.h>
 #include <openssl/bn.h>
 #include <openssl/err.h>
+#endif
 
 static const std::string base64_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 static inline bool is_base64(unsigned char c) { return (isalnum(c) || (c == '+') || (c == '/')); }
@@ -45,12 +45,28 @@ Crypt g_crypt;
 
 Crypt::Crypt()
 {
+#ifdef USE_GMP
+    mpz_init(m_p);
+    mpz_init(m_q);
+    mpz_init(m_d);
+    mpz_init(m_e);
+    mpz_init(m_n);
+#else
     m_rsa = RSA_new();
+#endif
 }
 
 Crypt::~Crypt()
 {
+#ifdef USE_GMP
+    mpz_clear(m_p);
+    mpz_clear(m_q);
+    mpz_clear(m_n);
+    mpz_clear(m_d);
+    mpz_clear(m_e);
+#else
     RSA_free(m_rsa);
+#endif
 }
 
 std::string Crypt::base64Encode(const std::string& decoded_string)
@@ -220,112 +236,12 @@ std::string Crypt::_decrypt(const std::string& encrypted_string, bool useMachine
     return std::string();
 }
 
-std::string Crypt::md5Encode(const std::string& decoded_string, bool upperCase)
-{
-    MD5_CTX c;
-    MD5_Init(&c);
-    MD5_Update(&c, decoded_string.c_str(), decoded_string.length());
-
-    uint8_t md[MD5_DIGEST_LENGTH];
-    MD5_Final(md, &c);
-
-    char output[(MD5_DIGEST_LENGTH << 1) + 1];
-    for(int32_t i = 0; i < (int32_t)sizeof(md); ++i)
-        sprintf(output + (i << 1), "%.2X", md[i]);
-
-    std::string result = output;
-    if(upperCase)
-        return result;
-
-    std::transform(result.begin(), result.end(), result.begin(), tolower);
-    return result;
-}
-
-std::string Crypt::sha1Encode(const std::string& decoded_string, bool upperCase)
-{
-    SHA_CTX c;
-    SHA1_Init(&c);
-    SHA1_Update(&c, decoded_string.c_str(), decoded_string.length());
-
-    uint8_t md[SHA_DIGEST_LENGTH];
-    SHA1_Final(md, &c);
-
-    char output[(SHA_DIGEST_LENGTH << 1) + 1];
-    for(int32_t i = 0; i < (int32_t)sizeof(md); ++i)
-        sprintf(output + (i << 1), "%.2X", md[i]);
-
-    std::string result = output;
-    if(upperCase)
-        return result;
-
-    std::transform(result.begin(), result.end(), result.begin(), tolower);
-    return result;
-}
-
-std::string Crypt::sha256Encode(const std::string& decoded_string, bool upperCase)
-{
-    SHA256_CTX c;
-    SHA256_Init(&c);
-    SHA256_Update(&c, decoded_string.c_str(), decoded_string.length());
-
-    uint8_t md[SHA256_DIGEST_LENGTH];
-    SHA256_Final(md, &c);
-
-    char output[(SHA256_DIGEST_LENGTH << 1) + 1];
-    for(int32_t i = 0; i < (int32_t)sizeof(md); ++i)
-        sprintf(output + (i << 1), "%.2X", md[i]);
-
-    std::string result = output;
-    if(upperCase)
-        return result;
-
-    std::transform(result.begin(), result.end(), result.begin(), tolower);
-    return result;
-}
-
-std::string Crypt::sha512Encode(const std::string& decoded_string, bool upperCase)
-{
-    SHA512_CTX c;
-    SHA512_Init(&c);
-    SHA512_Update(&c, decoded_string.c_str(), decoded_string.length());
-
-    uint8_t md[SHA512_DIGEST_LENGTH];
-    SHA512_Final(md, &c);
-
-    char output[(SHA512_DIGEST_LENGTH << 1) + 1];
-    for(int32_t i = 0; i < (int32_t)sizeof(md); ++i)
-        sprintf(output + (i << 1), "%.2X", md[i]);
-
-    std::string result = output;
-    if(upperCase)
-        return result;
-
-    std::transform(result.begin(), result.end(), result.begin(), tolower);
-    return result;
-}
-
-
-void Crypt::rsaGenerateKey(int bits, int e)
-{
-    // disabled because new OpenSSL changes broke
-    /*
-    RSA *rsa = RSA_new();
-    BIGNUM *ebn = BN_new();
-    BN_set_word(ebn, e);
-    RSA_generate_key_ex(rsa, bits, ebn, nullptr);
-    g_logger.info(stdext::format("%d bits (%d bytes) RSA key generated", bits, bits / 8));
-    g_logger.info(std::string("p = ") + BN_bn2dec(m_rsa->p));
-    g_logger.info(std::string("q = ") + BN_bn2dec(m_rsa->q));
-    g_logger.info(std::string("d = ") + BN_bn2dec(m_rsa->d));
-    g_logger.info(std::string("n = ") + BN_bn2dec(m_rsa->n));
-    g_logger.info(std::string("e = ") + BN_bn2dec(m_rsa->e));
-    BN_clear_free(ebn);
-    RSA_free(rsa);
-    */
-}
-
 void Crypt::rsaSetPublicKey(const std::string& n, const std::string& e)
 {
+#ifdef USE_GMP
+    mpz_set_str(m_n, n.c_str(), 10);
+    mpz_set_str(m_e, e.c_str(), 10);
+#else
 #if OPENSSL_VERSION_NUMBER < 0x10100005L
     BN_dec2bn(&m_rsa->n, n.c_str());
     BN_dec2bn(&m_rsa->e, e.c_str());
@@ -340,10 +256,19 @@ void Crypt::rsaSetPublicKey(const std::string& n, const std::string& e)
     BN_dec2bn(&be, e.c_str());
     RSA_set0_key(m_rsa, bn, be, nullptr);
 #endif
+#endif
 }
 
 void Crypt::rsaSetPrivateKey(const std::string& p, const std::string& q, const std::string& d)
 {
+#ifdef USE_GMP
+    mpz_set_str(m_p, p.c_str(), 10);
+    mpz_set_str(m_q, q.c_str(), 10);
+    mpz_set_str(m_d, d.c_str(), 10);
+
+    // n = p * q
+    mpz_mul(n, p, q);
+#else
 #if OPENSSL_VERSION_NUMBER < 0x10100005L
     BN_dec2bn(&m_rsa->p, p.c_str());
     BN_dec2bn(&m_rsa->q, q.c_str());
@@ -365,58 +290,69 @@ void Crypt::rsaSetPrivateKey(const std::string& p, const std::string& q, const s
     RSA_set0_key(m_rsa, nullptr, nullptr, bd);
     RSA_set0_factors(m_rsa, bp, bq);
 #endif
-}
-
-bool Crypt::rsaCheckKey()
-{
-    // only used by server, that sets both public and private
-    if(RSA_check_key(m_rsa)) {
-        BN_CTX *ctx = BN_CTX_new();
-        BN_CTX_start(ctx);
-
-        BIGNUM *r1 = BN_CTX_get(ctx), *r2 = BN_CTX_get(ctx);
-#if OPENSSL_VERSION_NUMBER < 0x10100005L
-        BN_mod(m_rsa->dmp1, m_rsa->d, r1, ctx);
-        BN_mod(m_rsa->dmq1, m_rsa->d, r2, ctx);
-        BN_mod_inverse(m_rsa->iqmp, m_rsa->q, m_rsa->p, ctx);
-#else
-        const BIGNUM *dmp1_c = nullptr, *d = nullptr, *dmq1_c = nullptr, *iqmp_c = nullptr, *q = nullptr, *p = nullptr;
-
-        RSA_get0_key(m_rsa, nullptr, nullptr, &d);
-        RSA_get0_factors(m_rsa, &p, &q);
-        RSA_get0_crt_params(m_rsa, &dmp1_c, &dmq1_c, &iqmp_c);
-
-        BIGNUM *dmp1 = BN_dup(dmp1_c), *dmq1 = BN_dup(dmq1_c), *iqmp = BN_dup(iqmp_c);
-
-        BN_mod(dmp1, d, r1, ctx);
-        BN_mod(dmq1, d, r2, ctx);
-        BN_mod_inverse(iqmp, q, p, ctx);
-        RSA_set0_crt_params(m_rsa, dmp1, dmq1, iqmp);
 #endif
-        return true;
-    }
-    else {
-        ERR_load_crypto_strings();
-        g_logger.error(stdext::format("RSA check failed - %s", ERR_error_string(ERR_get_error(), nullptr)));
-        return false;
-    }
 }
 
 bool Crypt::rsaEncrypt(unsigned char *msg, int size)
 {
-    if(size != RSA_size(m_rsa))
+    if(size != rsaGetSize())
         return false;
+
+#ifdef USE_GMP
+    mpz_t c, m;
+    mpz_init(c);
+    mpz_init(m);
+    mpz_import(m, size, 1, 1, 0, 0, msg);
+
+    // c = m^e mod n
+    mpz_powm(c, m, m_e, m_n);
+
+    size_t count = (mpz_sizeinbase(m, 2) + 7) / 8;
+    memset((char*)msg, 0, size - count);
+    mpz_export((char*)msg + (size - count), nullptr, 1, 1, 0, 0, c);
+
+    mpz_clear(c);
+    mpz_clear(m);
+
+    return true;
+#else
     return RSA_public_encrypt(size, msg, msg, m_rsa, RSA_NO_PADDING) != -1;
+#endif
 }
 
 bool Crypt::rsaDecrypt(unsigned char *msg, int size)
 {
-    if(size != RSA_size(m_rsa))
+    if(size != rsaGetSize())
         return false;
+
+#ifdef USE_GMP
+    mpz_t c, m;
+    mpz_init(c);
+    mpz_init(m);
+    mpz_import(c, size, 1, 1, 0, 0, msg);
+
+    // m = c^d mod n
+    mpz_powm(m, c, m_d, m_n);
+
+    size_t count = (mpz_sizeinbase(m, 2) + 7) / 8;
+    memset((char*)msg, 0, size - count);
+    mpz_export((char*)msg + (size - count), nullptr, 1, 1, 0, 0, m);
+
+    mpz_clear(c);
+    mpz_clear(m);
+
+    return true;
+#else
     return RSA_private_decrypt(size, msg, msg, m_rsa, RSA_NO_PADDING) != -1;
+#endif
 }
 
 int Crypt::rsaGetSize()
 {
+#ifdef USE_GMP
+    size_t count = (mpz_sizeinbase(m_n, 2) + 7) / 8;
+    return ((int)count / 128) * 128;
+#else
     return RSA_size(m_rsa);
+#endif
 }
diff --git a/src/framework/util/crypt.h b/src/framework/util/crypt.h
index 480fdebc..327ff067 100644
--- a/src/framework/util/crypt.h
+++ b/src/framework/util/crypt.h
@@ -27,8 +27,11 @@
 #include <string>
 
 #include <boost/uuid/uuid.hpp>
-
+#ifdef USE_GMP
+#include <gmp.h>
+#else
 typedef struct rsa_st RSA;
+#endif
 
 class Crypt
 {
@@ -44,15 +47,9 @@ public:
     std::string genUUID();
     bool setMachineUUID(std::string uuidstr);
     std::string getMachineUUID();
-    std::string md5Encode(const std::string& decoded_string, bool upperCase);
-    std::string sha1Encode(const std::string& decoded_string, bool upperCase);
-    std::string sha256Encode(const std::string& decoded_string, bool upperCase);
-    std::string sha512Encode(const std::string& decoded_string, bool upperCase);
 
-    void rsaGenerateKey(int bits, int e);
     void rsaSetPublicKey(const std::string& n, const std::string& e);
     void rsaSetPrivateKey(const std::string &p, const std::string &q, const std::string &d);
-    bool rsaCheckKey();
     bool rsaEncrypt(unsigned char *msg, int size);
     bool rsaDecrypt(unsigned char *msg, int size);
     int rsaGetSize();
@@ -62,7 +59,11 @@ private:
     std::string _decrypt(const std::string& encrypted_string, bool useMachineUUID);
     std::string getCryptKey(bool useMachineUUID);
     boost::uuids::uuid m_machineUUID;
+#ifdef USE_GMP
+    mpz_t m_p, m_q, m_n, m_e, m_d;
+#else
     RSA *m_rsa;
+#endif
 };
 
 extern Crypt g_crypt;