diff --git a/.gitmodules b/.gitmodules
index 4226383..e69de29 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +0,0 @@
-[submodule "easy-ecc"]
-	path = extern/easy-ecc
-	url = https://github.com/libAthena/easy-ecc.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b3c37b4..bbb8636 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,7 +19,7 @@ set(ATHENA_VERSION
 
 add_subdirectory(extern)
 
-include_directories(include ${LZO_INCLUDE_DIR} ${ZLIB_INCLUDE_DIR} ${EASYECC_INCLUDE_DIR})
+include_directories(include ${LZO_INCLUDE_DIR} ${ZLIB_INCLUDE_DIR})
 
 if (NOT MSVC)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
@@ -103,8 +103,8 @@ add_library(athena-wiisave EXCLUDE_FROM_ALL
     src/athena/WiiSave.cpp
     src/athena/WiiSaveReader.cpp
     src/athena/WiiSaveWriter.cpp
-#    src/bn.cpp
-#    src/ec.cpp
+    src/bn.cpp
+    src/ec.cpp
     src/md5.cpp
     src/sha1.cpp
     src/aes.cpp
@@ -116,8 +116,8 @@ add_library(athena-wiisave EXCLUDE_FROM_ALL
     include/athena/WiiSaveReader.hpp
     include/athena/WiiSaveWriter.hpp
     include/aes.hpp
-#    include/bn.h
-#    include/ec.h
+    include/bn.hpp
+    include/ec.hpp
     include/md5.h
     include/sha1.h
 )
diff --git a/extern/CMakeLists.txt b/extern/CMakeLists.txt
index 4600c53..211f1c0 100644
--- a/extern/CMakeLists.txt
+++ b/extern/CMakeLists.txt
@@ -1,4 +1,3 @@
 add_subdirectory(lzo)
 add_subdirectory(zlib)
 add_subdirectory(yaml)
-add_subdirectory(easy-ecc)
diff --git a/extern/easy-ecc b/extern/easy-ecc
deleted file mode 160000
index da27485..0000000
--- a/extern/easy-ecc
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit da2748507cbe429d3e1be918c54cfba3be06d4b2
diff --git a/include/athena/WiiSaveReader.hpp b/include/athena/WiiSaveReader.hpp
index 1c15242..9cf9a6d 100644
--- a/include/athena/WiiSaveReader.hpp
+++ b/include/athena/WiiSaveReader.hpp
@@ -21,7 +21,7 @@ namespace io
  *  all work is done using a memory buffer, and not read directly from the disk.
  *  \sa BinaryReader
  */
-class WiiSaveReader : protected MemoryCopyReader
+class WiiSaveReader : public MemoryCopyReader
 {
     MEMORYCOPYREADER_BASE();
 public:
diff --git a/include/bn.hpp b/include/bn.hpp
new file mode 100644
index 0000000..a3c1d43
--- /dev/null
+++ b/include/bn.hpp
@@ -0,0 +1,15 @@
+#ifndef BN_H
+#define BN_H
+
+#include "athena/Types.hpp"
+namespace bignum
+{
+int compare(const atUint8* a, const atUint8* b, atUint32 n);
+void subModulus(atUint8* a, const atUint8* N, atUint32 n);
+void add(atUint8* d, atUint8* a, const atUint8* b, const atUint8* N, atUint32 n);
+void mul(atUint8* d, atUint8* a, const atUint8* b, const atUint8* N, atUint32 n);
+void exp(atUint8* d, const atUint8* a, const atUint8* N, atUint32 n, atUint8* e, atUint32 en);
+void inv(atUint8* d, atUint8* a, const atUint8* N, atUint32 n);
+}
+
+#endif // BN_H
diff --git a/include/ec.hpp b/include/ec.hpp
new file mode 100644
index 0000000..8a9b42c
--- /dev/null
+++ b/include/ec.hpp
@@ -0,0 +1,13 @@
+#ifndef EC_H
+#define EC_H
+#include "athena/Types.hpp"
+
+namespace ecc
+{
+void checkEC(atUint8* ng, atUint8* ap, atUint8* sig, atUint8* sigHash, bool& apValid, bool& ngValid);
+void makeECCert(atUint8* cert, atUint8* sig, const char* signer, const char* name, atUint8* priv, atUint32 keyId);
+void createECDSA(atUint8* R, atUint8* S, atUint8* k, atUint8* hash);
+}
+
+#endif // EC_H
+
diff --git a/src/athena/WiiSaveReader.cpp b/src/athena/WiiSaveReader.cpp
index 1bbf069..2dfaf1c 100644
--- a/src/athena/WiiSaveReader.cpp
+++ b/src/athena/WiiSaveReader.cpp
@@ -7,7 +7,7 @@
 #include "athena/FileWriter.hpp"
 #include "md5.h"
 #include "aes.hpp"
-#include "ecc.h"
+#include "ec.hpp"
 #include "sha1.h"
 #include <iostream>
 #include <iomanip>
@@ -294,7 +294,6 @@ WiiFile* WiiSaveReader::readFile()
 
 void WiiSaveReader::readCerts(atUint32 totalSize)
 {
-#if 0
     std::cout << "Reading certs..." << std::endl;
     atUint32 dataSize = totalSize - 0x340;
     std::unique_ptr<atUint8[]> sig    = base::readUBytes(0x40);
@@ -307,22 +306,14 @@ void WiiSaveReader::readCerts(atUint32 totalSize)
     std::cout << "validating..." << std::endl;
     hash = getSha1(data.get(), dataSize);
     atUint8* hash2 = getSha1(hash, 20);
-    bool failed = false;
+    bool ngValid = false;
+    bool apValid = false;
+    ecc::checkEC(ngCert.get(), apCert.get(), sig.get(), hash2, apValid, ngValid);
 
-    if (!ecdsa_verify(ngCert.get(), hash, sig.get()))
-    {
-        std::cout << "NGCert failure" << std::endl;
-        failed = true;
-    }
-    if (!ecdsa_verify(apCert.get(), hash2, sig.get()))
-    {
-        std::cout << "APCert failure" << std::endl;
-        failed = true;
-    }
-
-    if (!failed)
-        std::cout << "certificates ok" << std::endl;
-#endif
+    if (apValid)
+        std::cout << "AP Certificate ok" << std::endl;
+    if (ngValid)
+        std::cout << "NG Certificate ok" << std::endl;
 }
 
 WiiFile* WiiSaveReader::buildTree(std::vector<WiiFile*> files)
diff --git a/src/athena/WiiSaveWriter.cpp b/src/athena/WiiSaveWriter.cpp
index 5c48906..7ffc239 100644
--- a/src/athena/WiiSaveWriter.cpp
+++ b/src/athena/WiiSaveWriter.cpp
@@ -10,7 +10,7 @@
 #include "athena/Utility.hpp"
 
 #include "aes.hpp"
-#include "ecc.h"
+#include "ec.hpp"
 #include "md5.h"
 #include "sha1.h"
 
@@ -194,7 +194,6 @@ void WiiSaveWriter::writeImage(WiiImage* image)
 
 void WiiSaveWriter::writeCerts(atUint32 filesSize, atUint32 ngId, atUint8* ngPriv, atUint8* ngSig, atUint32 ngKeyId)
 {
-#if 0
     atUint8  sig[0x40];
     atUint8  ngCert[0x180];
     atUint8  apCert[0x180];
@@ -208,7 +207,7 @@ void WiiSaveWriter::writeCerts(atUint32 filesSize, atUint32 ngId, atUint8* ngPri
 
     sprintf(signer, "Root-CA00000001-MS00000002");
     sprintf(name, "NG%08x", ngId);
-    make_ec_cert(ngCert, ngSig, signer, name, ngPriv, ngKeyId);
+    ecc::makeECCert(ngCert, ngSig, signer, name, ngPriv, ngKeyId);
 
     memset(apPriv, 0, 30);
     apPriv[10] = 1;
@@ -217,11 +216,11 @@ void WiiSaveWriter::writeCerts(atUint32 filesSize, atUint32 ngId, atUint8* ngPri
 
     sprintf(signer, "Root-CA00000001-MS00000002-NG%08x", ngId);
     sprintf(name, "AP%08x%08x", 1, 2);
-    make_ec_cert(apCert, apSig, signer, name, apPriv, 0);
+    ecc::makeECCert(apCert, apSig, signer, name, apPriv, 0);
 
     hash = getSha1(apCert + 0x80, 0x100);
-    generate_ecdsa(apSig, apSig + 30, ngPriv, hash);
-    make_ec_cert(apCert, apSig, signer, name, apPriv, 0);
+    ecc::createECDSA(apSig, apSig + 30, ngPriv, hash);
+    ecc::makeECCert(apCert, apSig, signer, name, apPriv, 0);
     delete[] hash;
 
     dataSize = filesSize + 0x80;
@@ -234,7 +233,7 @@ void WiiSaveWriter::writeCerts(atUint32 filesSize, atUint32 ngId, atUint8* ngPri
     delete[] hash;
     delete[] data;
 
-    generate_ecdsa(sig, sig + 30, apPriv, hash2);
+    ecc::createECDSA(sig, sig + 30, apPriv, hash2);
     int stuff = 0x2f536969;
 
     if (!utility::isSystemBigEndian())
@@ -246,7 +245,6 @@ void WiiSaveWriter::writeCerts(atUint32 filesSize, atUint32 ngId, atUint8* ngPri
     base::writeBytes((atInt8*)sig, 0x40);
     base::writeBytes((atInt8*)ngCert, 0x180);
     base::writeBytes((atInt8*)apCert, 0x180);
-#endif
 }
 
 } // io
diff --git a/src/bn.cpp b/src/bn.cpp
new file mode 100644
index 0000000..a4d0a62
--- /dev/null
+++ b/src/bn.cpp
@@ -0,0 +1,98 @@
+#include <string.h>
+#include <stdio.h>
+
+#include "bn.hpp"
+
+namespace bignum
+{
+
+void subModulus(atUint8* a, const atUint8* N, atUint32 n)
+{
+    atUint8 c = 0;
+
+    for (atUint32 i = n - 1; i < n; i--)
+    {
+        atUint32 dig = N[i] + c;
+        c = (a[i] < dig);
+        a[i] -= dig;
+    }
+}
+
+void add(atUint8* d, atUint8* a, const atUint8* b, const atUint8* N, atUint32 n)
+{
+    atUint8 c = 0;
+
+    for (atUint32 i = n - 1; i < n; i--)
+    {
+        atUint32 dig = a[i] + b[i] + c;
+        c = (dig >= 0x100);
+        d[i] = dig;
+    }
+
+    if (c)
+        subModulus(d, N, n);
+
+    if (compare(d, N, n) >= 0)
+        subModulus(d, N, n);
+}
+
+void mul(atUint8* d, atUint8* a, const atUint8* b, const atUint8* N, atUint32 n)
+{
+    memset(d, 0, n);
+
+    for (atUint32 i = 0; i < n; i++)
+    {
+        for (atUint8 mask = 0x80; mask != 0; mask >>= 1)
+        {
+            add(d, d, d, N, n);
+
+            if ((a[i] & mask) != 0)
+                add(d, d, b, N, n);
+        }
+    }
+}
+
+void exp(atUint8* d, const atUint8* a, const atUint8* N, atUint32 n, atUint8* e, atUint32 en)
+{
+    atUint8 t[512];
+    memset(d, 0, n);
+    d[n - 1] = 1;
+
+    for (atUint32 i = 0; i < en; i++)
+    {
+        for (atUint8 mask = 0x80; mask != 0; mask >>= 1)
+        {
+            mul(t, d, d, N, n);
+
+            if ((e[i] & mask) != 0)
+                mul(d, t, a, N, n);
+            else
+                memcpy(d, t, n);
+        }
+    }
+}
+
+void inv(atUint8* d, atUint8* a, const atUint8* N, atUint32 n)
+{
+    atUint8 t[512], s[512];
+
+    memcpy(t, N, n);
+    memset(s, 0, n);
+    s[n - 1] = 2;
+    subModulus(t, s, n);
+    exp(d, a, N, n, t, n);
+}
+
+int compare(const atUint8* a, const atUint8* b, atUint32 n)
+{
+    for (atUint32 i = 0; i < n; i++)
+    {
+        if (a[i] < b[i])
+            return -1;
+
+        if (a[i] > b[i])
+            return 1;
+    }
+    return 0;
+}
+}
diff --git a/src/ec.cpp b/src/ec.cpp
new file mode 100644
index 0000000..7241827
--- /dev/null
+++ b/src/ec.cpp
@@ -0,0 +1,320 @@
+#include <string.h>
+#include "athena/Utility.hpp"
+
+#include "bn.hpp"
+#include "ec.hpp"
+#include "sha1.h"
+
+namespace ecc
+{
+static int checkZero(const atUint8* d) { return !memcmp(d, d + 1, 29) && d[0] == 0; }
+
+static void add(atUint8* d, const atUint8* a, const atUint8* b)
+{
+    for (atUint32 i = 0; i < 30; i++)
+        d[i] = a[i] ^ b[i];
+}
+
+static void multiply(atUint8* d, const atUint8* a, const atUint8* b)
+{
+    memset(d, 0, 30);
+    for (atUint32 n = 0, i = 0, mask = 1; n < 233; n++)
+    {
+        atUint8 x, y;
+        atUint8 carry = d[0] & 1;
+        x = 0;
+        for (atUint32 i = 0; i < 29; i++)
+        {
+            y = d[i + 1];
+            d[i] = x ^ (y >> 7);
+            x = y << 1;
+        }
+
+        d[29] = x ^ carry;
+        d[20] ^= carry << 2;
+        if ((a[i] & mask) != 0)
+            add(d, d, b);
+
+        mask >>= 1;
+        if (mask == 0)
+        {
+            mask = 0x80;
+            i++;
+        }
+    }
+}
+
+static void squareToWide(atUint8* d, const atUint8* a)
+{
+    static const atUint8 sq[16] = {0x00, 0x01, 0x04, 0x05, 0x10, 0x11, 0x14, 0x15,
+                                   0x40, 0x41, 0x44, 0x45, 0x50, 0x51, 0x54, 0x55};
+    for (atUint32 i = 0; i < 30; i++)
+    {
+        d[2 * i] = sq[a[i] >> 4];
+        d[2 * i + 1] = sq[a[i] & 15];
+    }
+}
+
+static void wideReduce(atUint8* d)
+{
+    atUint32 i;
+    atUint8 x;
+
+    for (i = 0; i < 30; i++)
+    {
+        x = d[i];
+
+        d[i + 19] ^= x >> 7;
+        d[i + 20] ^= x << 1;
+        d[i + 29] ^= x >> 1;
+        d[i + 30] ^= x << 7;
+    }
+
+    x = d[30] & ~1;
+    d[49] ^= x >> 7;
+    d[50] ^= x << 1;
+    d[59] ^= x >> 1;
+    d[30] &= 1;
+}
+
+static void square(atUint8* d, const atUint8* a)
+{
+    atUint8 wide[60];
+
+    squareToWide(wide, a);
+    wideReduce(wide);
+
+    memcpy(d, wide + 30, 30);
+}
+
+static void itInvert(atUint8* d, const atUint8* a, const atUint8* b, atUint32 j)
+{
+    atUint8 t[30];
+    memcpy(t, a, 32);
+    while (j--)
+    {
+        square(d, t);
+        memcpy(t, d, 30);
+    }
+    multiply(d, t, b);
+}
+
+static void invert(atUint8* d, const atUint8* a)
+{
+    atUint8 t[30];
+    atUint8 s[30];
+
+    itInvert(t, a, a, 1);
+    itInvert(s, t, a, 1);
+    itInvert(t, s, s, 3);
+    itInvert(s, t, a, 1);
+    itInvert(t, s, s, 7);
+    itInvert(s, t, t, 14);
+    itInvert(t, s, a, 1);
+    itInvert(s, t, t, 29);
+    itInvert(t, s, s, 58);
+    itInvert(s, t, t, 116);
+    square(d, s);
+}
+
+static void pointDouble(atUint8* r, const atUint8* p)
+{
+    atUint8 s[30], t[30];
+    const atUint8* px = p;
+    const atUint8* py = p + 30;
+    atUint8* rx = r;
+    atUint8* ry = r + 30;
+
+    if (checkZero(px))
+    {
+        memset(rx, 0, 30);
+        memset(ry, 0, 30);
+
+        return;
+    }
+
+    invert(t, px);
+    multiply(s, py, t);
+    add(s, s, px);
+
+    square(t, px);
+
+    square(rx, s);
+    add(rx, rx, s);
+    rx[29] ^= 1;
+
+    multiply(ry, s, rx);
+    add(ry, ry, rx);
+    add(ry, ry, t);
+}
+
+static void pointAdd(atUint8* r, const atUint8* p, const atUint8* q)
+{
+    atUint8 s[30], t[30], u[30];
+    const atUint8* px = p;
+    const atUint8* py = p + 30;
+    const atUint8* qx = q;
+    const atUint8* qy = q + 30;
+    atUint8* rx = r;
+    atUint8* ry = r + 30;
+
+    if (checkZero(p) && checkZero(p + 30))
+    {
+        memcpy(rx, qx, 30);
+        memcpy(ry, qy, 30);
+        return;
+    }
+
+    if (checkZero(p) && checkZero(p + 30))
+    {
+        memcpy(rx, px, 30);
+        memcpy(ry, py, 30);
+        return;
+    }
+
+    add(u, px, qx);
+
+    if (checkZero(u))
+    {
+        add(u, py, qy);
+
+        if (checkZero(u))
+            pointDouble(r, p);
+        else
+        {
+            memset(rx, 0, 30);
+            memset(ry, 0, 30);
+        }
+
+        return;
+    }
+
+    invert(t, u);
+    add(u, py, qy);
+    multiply(s, t, u);
+
+    square(t, s);
+    add(t, t, s);
+    add(t, t, qx);
+    t[29] ^= 1;
+
+    multiply(u, s, t);
+    add(s, u, py);
+    add(rx, t, px);
+    add(ry, s, rx);
+}
+
+static void pointMultiply(atUint8* d, const atUint8* a, const atUint8* b)
+{
+    memset(d, 0, 30);
+    memset(d + 30, 0, 30);
+    for (atUint32 i = 0; i < 30; i++)
+    {
+        for (atUint8 mask = 0x80; mask != 0; mask >>= 1)
+        {
+            pointDouble(d, d);
+
+            if ((a[i] & mask) != 0)
+                pointAdd(d, d, b);
+        }
+    }
+}
+
+static const atUint8 ecG[60] = {0x00, 0xfa, 0xc9, 0xdf, 0xcb, 0xac, 0x83, 0x13, 0xbb, 0x21, 0x39, 0xf1,
+                                0xbb, 0x75, 0x5f, 0xef, 0x65, 0xbc, 0x39, 0x1f, 0x8b, 0x36, 0xf8, 0xf8,
+                                0xeb, 0x73, 0x71, 0xfd, 0x55, 0x8b, 0x01, 0x00, 0x6a, 0x08, 0xa4, 0x19,
+                                0x03, 0x35, 0x06, 0x78, 0xe5, 0x85, 0x28, 0xbe, 0xbf, 0x8a, 0x0b, 0xef,
+                                0xf8, 0x67, 0xa7, 0xca, 0x36, 0x71, 0x6f, 0x7e, 0x01, 0xf8, 0x10, 0x52};
+
+static const atUint8 ecN[30] = {0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                                0x00, 0x00, 0x00, 0x00, 0x00, 0x13, 0xe9, 0x74, 0xe7, 0x2f,
+                                0x8a, 0x69, 0x22, 0x03, 0x1d, 0x26, 0x03, 0xcf, 0xe0, 0xd7};
+
+bool checkECDSA(atUint8* Q, atUint8* R, atUint8* S, atUint8* hash)
+{
+    atUint8 Sinv[30];
+    atUint8 e[30];
+    atUint8 w1[30], w2[30];
+    atUint8 r1[60], r2[60];
+
+    bignum::inv(Sinv, S, ecN, 30);
+
+    memset(e, 0, 30);
+    memcpy(e + 10, hash, 20);
+
+    bignum::mul(w1, e, Sinv, ecN, 30);
+    bignum::mul(w2, R, Sinv, ecN, 30);
+
+    pointMultiply(r1, w1, ecG);
+    pointMultiply(r2, w2, Q);
+
+    pointAdd(r1, r1, r2);
+
+    if (bignum::compare(r1, ecN, 30) >= 0)
+        bignum::subModulus(r1, ecN, 30);
+
+    return (bignum::compare(r1, R, 30) == 0);
+}
+
+void makeECCert(atUint8* cert, atUint8* sig, const char* signer, const char* name, atUint8* priv, atUint32 keyId)
+{
+    memset(cert, 0, 0x180);
+    *(atUint32*)(cert) = 0x10002;
+
+    if (!athena::utility::isSystemBigEndian())
+        *(atUint32*)(cert) = athena::utility::swapU32(*(atUint32*)(cert));
+
+    memcpy((char*)cert + 4, sig, 60);
+    strcpy((char*)cert + 0x80, signer);
+    *(atUint32*)(cert + 0xc0) = 2;
+
+    if (!athena::utility::isSystemBigEndian())
+        *(atUint32*)(cert + 0xc0) = athena::utility::swapU32(*(atUint32*)(cert + 0xc0));
+
+    strcpy((char*)cert + 0xc4, name);
+    *(atUint32*)(cert + 0x104) = keyId;
+
+    if (!athena::utility::isSystemBigEndian())
+        *(atUint32*)(cert + 0x104) = athena::utility::swapU32(*(atUint32*)(cert + 0x104));
+
+    pointMultiply(cert + 0x108, priv, ecG);
+}
+
+void createECDSA(atUint8* R, atUint8* S, atUint8* k, atUint8* hash)
+{
+    atUint8 e[30];
+    atUint8 kk[30];
+    atUint8 m[30];
+    atUint8 minv[30];
+    atUint8 mG[60];
+
+    memset(e, 0, 30);
+    memcpy(e + 10, hash, 20);
+
+    athena::utility::fillRandom(m, sizeof(m));
+    m[0] = 0;
+
+    pointMultiply(mG, m, ecG);
+    memcpy(R, mG, 30);
+
+    if (bignum::compare(R, ecN, 30) >= 0)
+        bignum::subModulus(R, ecN, 30);
+
+    memcpy(kk, k, 30);
+
+    if (bignum::compare(kk, ecN, 30) >= 0)
+        bignum::subModulus(kk, ecN, 30);
+
+    bignum::mul(S, R, kk, ecN, 30);
+    bignum::add(kk, S, e, ecN, 30);
+    bignum::inv(minv, m, ecN, 30);
+    bignum::mul(S, minv, kk, ecN, 30);
+}
+
+void checkEC(atUint8* ng, atUint8* ap, atUint8* sig, atUint8* sigHash, bool& apValid, bool& ngValid)
+{
+    atUint8* apHash = getSha1(ap + 0x80, 0x100);
+    ngValid = checkECDSA(ng + 0x0108, ap + 0x04, ap + 0x22, apHash);
+    apValid = checkECDSA(ap + 0x0108, sig, sig + 30, sigHash);
+}
+}