diff --git a/src/cc/CCinclude.h b/src/cc/CCinclude.h
index 66c001969..5d847800a 100644
--- a/src/cc/CCinclude.h
+++ b/src/cc/CCinclude.h
@@ -42,6 +42,7 @@ one other technical note is that komodod has the insight-explorer extensions bui
 #include <cryptoconditions.h>
 #include "../script/standard.h"
 #include "../base58.h"
+#include "../key.h"
 #include "../core_io.h"
 #include "../script/sign.h"
 #include "../wallet/wallet.h"
@@ -179,6 +180,7 @@ int32_t oracle_format(uint256 *hashp,int64_t *valp,char *str,uint8_t fmt,uint8_t
 CPubKey GetUnspendable(struct CCcontract_info *cp,uint8_t *unspendablepriv);
 
 // CCutils
+bool priv2addr(char *coinaddr,uint8_t buf33[33],uint8_t priv32[32]);
 CPubKey buf2pk(uint8_t *buf33);
 void endiancpy(uint8_t *dest,uint8_t *src,int32_t len);
 uint256 DiceHashEntropy(uint256 &entropy,uint256 _txidpriv,int32_t entropyvout,int32_t usevout);
diff --git a/src/cc/CCutils.cpp b/src/cc/CCutils.cpp
index 766ce1188..6dff5d3cd 100644
--- a/src/cc/CCutils.cpp
+++ b/src/cc/CCutils.cpp
@@ -442,6 +442,20 @@ bool PreventCC(Eval* eval,const CTransaction &tx,int32_t preventCCvins,int32_t n
     return(true);
 }
 
+bool priv2addr(char *coinaddr,uint8_t *buf33,uint8_t priv32[32])
+{
+    CKey priv; CPubKey pk; int32_t i; uint8_t *src;
+    priv.SetKey32(priv32);
+    pk = priv.GetPubKey();
+    if ( buf33 != 0 )
+    {
+        src = (uint8_t *)pk.begin();
+        for (i=0; i<33; i++)
+            buf33[i] = src[i];
+    }
+    return(Getscriptaddress(coinaddr, CScript() << ParseHex(HexStr(pk)) << OP_CHECKSIG));
+}
+
 std::vector<uint8_t> Mypubkey()
 {
     extern uint8_t NOTARY_PUBKEY33[33];
@@ -456,7 +470,7 @@ std::vector<uint8_t> Mypubkey()
 
 bool Myprivkey(uint8_t myprivkey[])
 {
-    char coinaddr[64]; std::string strAddress; char *dest; int32_t i,n; CBitcoinAddress address; CKeyID keyID; CKey vchSecret;
+    char coinaddr[64],checkaddr[64]; std::string strAddress; char *dest; int32_t i,n; CBitcoinAddress address; CKeyID keyID; CKey vchSecret; uint8_t buf33[33];
     if ( Getscriptaddress(coinaddr,CScript() << Mypubkey() << OP_CHECKSIG) != 0 )
     {
         n = (int32_t)strlen(coinaddr);
@@ -477,7 +491,13 @@ bool Myprivkey(uint8_t myprivkey[])
                         fprintf(stderr,"0x%02x, ",myprivkey[i]);
                     fprintf(stderr," found privkey for %s!\n",dest);
                 }
-                return(true);
+                if ( priv2addr(checkaddr,buf33,myprivkey) != 0 )
+                {
+                    if ( buf2pk(buf33) == Mypubkey() && strcmp(checkaddr,coinaddr) == 0 )
+                        return(true);
+                    else printf("mismatched privkey -> addr %s vs %s\n",checkaddr,coinaddr);
+                }
+                return(false);
             }
 #endif
         }
diff --git a/src/cc/sudoku.cpp b/src/cc/sudoku.cpp
new file mode 100644
index 000000000..a79e3d161
--- /dev/null
+++ b/src/cc/sudoku.cpp
@@ -0,0 +1,476 @@
+
+// start https://github.com/mentalmove/SudokuGenerator
+//
+//  main.c
+//  SudokuGenerator
+//
+//  Malte Pagel
+//
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <string.h>
+#include <math.h>
+
+
+#define SMALL_LINE 3
+#define LINE 9
+#define TOTAL 81
+
+#define LIMIT 16777216
+
+#define SHOW_SOLVED 1
+
+
+struct dimensions_collection {
+    int row;
+    int column;
+    int small_square;
+};
+
+
+static int indices[TOTAL];
+static int riddle[TOTAL];
+static int solved[TOTAL];
+static int unsolved[TOTAL];
+static int tries_to_set = 0;
+static int taking_back;
+static int global_unset_count = 0;
+
+
+struct dimensions_collection get_collection(int);
+int contains_element(int*, int, int);
+void get_horizontal(int, int*);
+void get_vertical(int, int*);
+void get_square(int, int*);
+int set_values(int, int);
+void take_back(int);
+
+int show_solution(int*);
+
+
+int show_solution (int* solution) {
+    
+    int i;
+    int counter = 0;
+    
+    printf( " -----------------------------------\n" );
+    
+    for ( i = 0; i < TOTAL; i++ ) {
+        if ( i % LINE == 0 )
+            printf( "|" );
+        
+        if ( solution[i] ) {
+            printf( " %d ", solution[i]);
+            counter++;
+        }
+        else
+            printf( "   ");
+        
+        if ( i % LINE == (LINE - 1) ) {
+            printf( "|\n" );
+            if ( i != (TOTAL - 1) ) {
+                if ( i % (SMALL_LINE * LINE) == (SMALL_LINE * LINE - 1) )
+                    printf( "|-----------+-----------+-----------|\n" );
+                else
+                    printf( "|- - - - - -|- - - - - -|- - - - - -|\n" );
+            }
+        }
+        else {
+            if ( i % SMALL_LINE == (SMALL_LINE - 1) )
+                printf( "|");
+            else
+                printf( ":" );
+        }
+    }
+    
+    printf( " -----------------------------------" );
+    
+    return counter;
+}
+
+
+/**
+ * Takes a position inside the large square and returns
+ *		- the row number
+ *		- the column number
+ *		- the small square number
+ * where this position is situated in
+ */
+struct dimensions_collection get_collection (int index) {
+    struct dimensions_collection ret;
+    
+    ret.row = (int) (index / LINE);
+    ret.column = index % LINE;
+    ret.small_square = SMALL_LINE * (int) (ret.row / SMALL_LINE) + (int) (ret.column / SMALL_LINE);
+    
+    return ret;
+}
+
+/**
+ * Is 'the_element' in 'the_array'?
+ */
+int contains_element (int* the_array, int the_element, int length) {
+    for ( int i = 0; i < length; i++ )
+        if ( the_array[i] == the_element )
+            return 1;
+    return 0;
+}
+
+/**
+ * Sets all members of row 'row'
+ */
+void get_horizontal (int row, int* ret) {
+    int j = 0;
+    for ( int i = (row * LINE); i < (row * LINE) + LINE; i++ )
+        ret[j++] = riddle[i];
+}
+/**
+ * Sets all members of column 'col'
+ */
+void get_vertical (int col, int* ret) {
+    int j = 0;
+    for ( int i = col; i < TOTAL; i += LINE )
+        ret[j++] = riddle[i];
+}
+/**
+ * Sets all members of small square 'which'
+ */
+void get_square (int which, int* ret) {
+    for ( int i = 0; i < SMALL_LINE; i++ )
+        for ( int j = 0; j < SMALL_LINE; j++ )
+            ret[SMALL_LINE * i + j] = riddle[LINE * i + which * SMALL_LINE + j + ((int) (which / SMALL_LINE) * (SMALL_LINE - 1) * LINE)];
+}
+
+/**
+ * Recursive function:
+ * Try for each position the numbers from 1 to LINE
+ *      (except 'forbidden_number' if given).
+ * If all numbers collide with already set numbers, move is bad.
+ * If a number doesn't collide with already set numbers,
+ *	- move is bad if next move collides with the already set numbers
+ *              (including actual one)
+ *	- move is good if it's the last one
+ */
+int set_values (int index, int forbidden_number) {
+    
+    if ( taking_back && tries_to_set > (2 * LIMIT) )
+        return 1;
+    
+    int real_index = indices[index];
+    struct dimensions_collection blocks = get_collection(real_index);
+    int elements[LINE];
+    
+    for ( int i = 1; i <= LINE; i++ ) {
+        if ( forbidden_number && i == forbidden_number )
+            continue;
+        
+        tries_to_set++;
+        
+        get_horizontal(blocks.row, elements);
+        if ( contains_element(elements, i, LINE) )
+            continue;
+        
+        get_vertical(blocks.column, elements);
+        if ( contains_element(elements, i, LINE) )
+            continue;
+        
+        get_square(blocks.small_square, elements);
+        if ( contains_element(elements, i, LINE) )
+            continue;
+        
+        riddle[real_index] = i;
+        
+        if ( index == (TOTAL - 1) || set_values((index + 1), 0) )
+            return 1;
+    }
+    
+    riddle[real_index] = 0;
+    
+    return 0;
+}
+
+/**
+ * Some steps to hide unnecessary numbers:
+ *	a) Define last piece as 'special piece'
+ *	b) Remember this piece's value
+ *	c) Try to create riddle from this position on,
+ *          but forbid the value of the special piece
+ *	d)	I)  If operation fails, define the piece before the special piece
+ *          as 'special piece' and continue with b)
+ *		II) If operation is possible, reset 'special piece'
+ *			and put it to start of list
+ *	e) Stop if all pieces are tried or calculation limit is reached
+ */
+void take_back (int unset_count) {
+    
+    global_unset_count++;
+    
+    int i;
+    
+    int tmp = riddle[indices[TOTAL - unset_count]];
+    int redundant = set_values((TOTAL - unset_count), tmp);
+    
+    if ( !redundant ) {
+        unsolved[indices[TOTAL - unset_count]] = 0;
+        take_back(++unset_count);
+    }
+    else {
+        riddle[indices[TOTAL - unset_count]] = tmp;
+        for ( i = 1; i < unset_count; i++ )
+            riddle[indices[TOTAL - unset_count + i]] = 0;
+        
+        for ( i = (TOTAL - unset_count); i > 0; i-- )
+            indices[i] = indices[i - 1];
+        indices[0] = tmp;
+        
+        if ( global_unset_count < TOTAL && tries_to_set < LIMIT )
+            take_back(unset_count);
+    }
+}
+
+
+int sudoku(uint8_t solved9[LINE][LINE],uint8_t unsolved9[LINE][LINE],uint32_t srandi)
+{
+    int i, j, random, small_rows, small_cols, tmp, redundant,ind;
+    int multi_raw[LINE][LINE];
+    
+    memset(indices,0,sizeof(indices));
+    memset(solved,0,sizeof(solved));
+    memset(unsolved,0,sizeof(unsolved));
+    tries_to_set = 0;
+    taking_back = 0;
+    global_unset_count = 0;
+    
+    //time_t t;
+    //time(&t);
+    srand(srandi);
+    
+    /**
+     * Initialization:
+     * Fields are set to 0 ( i.e. we dont' know the number yet)
+     */
+    for ( i = 0; i < TOTAL; i++ )
+        riddle[i] = 0;
+    
+    /**
+     * Second initialization:
+     * LINE times numbers from 0 to (LINE - 1),
+     * i.e. every square
+     */
+    int big_rows_array[] = {0, 1, 2};
+    int big_cols_array[] = {0, 1, 2};
+    random = rand() % 4;
+    switch (random) {
+        case 1:
+            big_rows_array[0] = 2;
+            big_rows_array[1] = 1;
+            big_rows_array[2] = 0;
+            break;
+        case 2:
+            big_cols_array[0] = 2;
+            big_cols_array[1] = 1;
+            big_cols_array[2] = 0;
+            break;
+        case 3:
+            big_rows_array[0] = 2;
+            big_rows_array[1] = 1;
+            big_rows_array[2] = 0;
+            big_cols_array[0] = 2;
+            big_cols_array[1] = 1;
+            big_cols_array[2] = 0;
+    }
+    int big_rows, big_cols, big_rows_index, big_cols_index, start_value;
+    i = 0;
+    j = 0;
+    for ( big_rows_index = 0; big_rows_index < SMALL_LINE; big_rows_index++ ) {
+        big_rows = big_rows_array[big_rows_index];
+        for ( big_cols_index = 0; big_cols_index < SMALL_LINE; big_cols_index++ ) {
+            big_cols = big_cols_array[big_cols_index];
+            start_value = big_rows * LINE * SMALL_LINE + (big_cols * SMALL_LINE);
+            for ( small_rows = 0; small_rows < SMALL_LINE; small_rows++ )
+                for ( small_cols = 0; small_cols < SMALL_LINE; small_cols++ )
+                    multi_raw[i][j++] = small_rows * LINE + small_cols + start_value;
+            i++;
+            j = 0;
+        }
+    }
+    
+    
+    /**
+     * Randomization for every element of multi_raw.
+     * Suffle only inside squares
+     */
+    for ( i = 0; i < LINE; i++ ) {
+        for ( j = 0; j < LINE; j++ ) {
+            random = rand() % LINE;
+            if ( j == random )
+                continue;
+            tmp = multi_raw[i][j];
+            multi_raw[i][j] = multi_raw[i][random];
+            multi_raw[i][random] = tmp;
+        }
+    }
+    
+    /**
+     * Linearization
+     */
+    for ( i = 0; i < LINE; i++ )
+        for ( j = 0; j < LINE; j++ )
+            indices[i * LINE + j] = multi_raw[i][j];
+    
+    
+    /**
+     * Setting numbers, start with the first one.
+     * Variable 'redundant' is needed only for formal reasons
+     */
+    taking_back = 0;
+    redundant = set_values(0, 0);
+    
+    
+    memcpy(solved, riddle, (TOTAL * sizeof(int)));
+    memcpy(unsolved, riddle, (TOTAL * sizeof(int)));
+    
+    
+    /**
+     * Exchanging some (few) indices for more randomized game
+     */
+    int random2;
+    for ( i = (LINE - 1); i > 0; i-- ) {
+        for ( j = 0; j < (int) (sqrt(i)); j++ ) {
+            
+            if ( !(rand() % ((int) (i * sqrt(i)))) || !(LINE - j) )
+                continue;
+            
+            random = i * LINE + (int) (rand() % (LINE - j));
+            random2 = rand() % TOTAL;
+            
+            if ( random == random2 )
+                continue;
+            
+            tmp = indices[random];
+            indices[random] = indices[random2];
+            indices[random2] = tmp;
+        }
+    }
+    
+    
+    tries_to_set = 0;
+    taking_back = 1;
+    take_back(1);
+    
+    
+    if ( SHOW_SOLVED ) {
+        printf( "\n\n" );
+        redundant = show_solution(solved);
+    }
+    
+    int counter = show_solution(unsolved);
+    printf( "\t *** %d numbers left *** \n", counter );
+    ind = 0;
+    for (i=0; i<LINE; i++)
+        for (j=0; j<LINE; j++,ind++)
+        {
+            solved9[i][j] = solved[ind];
+            unsolved9[i][j] = unsolved[ind];
+        }
+    
+    return 0;
+}
+// end https://github.com/mentalmove/SudokuGenerator
+
+/******************************************************************************
+ * Copyright © 2014-2019 The SuperNET Developers.                             *
+ *                                                                            *
+ * See the AUTHORS, DEVELOPER-AGREEMENT and LICENSE files at                  *
+ * the top-level directory of this distribution for the individual copyright  *
+ * holder information and the developer policies on copyright and licensing.  *
+ *                                                                            *
+ * Unless otherwise agreed in a custom licensing agreement, no part of the    *
+ * SuperNET software, including this file may be copied, modified, propagated *
+ * or distributed except according to the terms contained in the LICENSE file *
+ *                                                                            *
+ * Removal or modification of this copyright notice is prohibited.            *
+ *                                                                            *
+ ******************************************************************************/
+
+#define SUDOKU_NINETH 387420489
+
+void sudoku_rowdisp(uint32_t x)
+{
+    int32_t i; char vals[10],val;
+    x %= SUDOKU_NINETH;
+    for (i=0; i<9; i++)
+    {
+        val = (x % 9);
+        vals[i] = '1' + val;
+        //printf("%d",val);
+        x /= 9;
+    }
+    vals[i++] = 0;
+    printf("%s\n",vals);
+}
+
+int32_t sudoku_privkeydisp(uint8_t key32[32])
+{
+    uint8_t i,val,flags[9]; char str[10]; uint32_t x,ind;
+    memset(flags,0,sizeof(flags));
+    ind = 0;
+    for (i=0; i<8; i++)
+    {
+        x = (uint32_t)key32[ind++] << 24;
+        x += (uint32_t)key32[ind++] << 16;
+        x += (uint32_t)key32[ind++] << 8;
+        x += (uint32_t)key32[ind++];
+        sudoku_rowdisp(x);
+        val = (x / SUDOKU_NINETH);
+        flags[val]++;
+        str[i] = val + '1';
+    }
+    for (i=0; i<9; i++)
+        if ( flags[i] == 0 )
+        {
+            str[8] = i + '1';
+            str[9] = 0;
+            printf("%s\n",str);
+            return(0);
+        }
+    return(-1);
+}
+
+void sudoku_privkey(uint8_t *privkey,uint8_t vals9[9][9])
+{
+    uint32_t x,keyvals[8]; int32_t i,j,ind;
+    for (i=0; i<9; i++)
+    {
+        x = 0;
+        for (j=8; j>=0; j--)
+        {
+            x *= 9;
+            x += vals9[i][j]-1;
+        }
+        if ( i < 8 )
+            keyvals[i] = x;
+        else
+        {
+            for (j=0; j<8; j++)
+                keyvals[j] += SUDOKU_NINETH * (vals9[i][j]-1);
+        }
+    }
+    for (i=ind=0; i<8; i++)
+    {
+        privkey[ind++] = ((keyvals[i] >> 24) & 0xff);
+        privkey[ind++] = ((keyvals[i] >> 16) & 0xff);
+        privkey[ind++] = ((keyvals[i] >> 8) & 0xff);
+        privkey[ind++] = (keyvals[i] & 0xff);
+    }
+}
+
+void sudoku_gen(uint8_t key32[32],uint8_t unsolved[9][9],uint32_t srandi)
+{
+    uint8_t vals9[9][9],uniq9[9][9]; int32_t i,j;
+    sudoku(vals9,unsolved,srandi);
+    sudoku_privkey(key32,vals9);
+    sudoku_privkeydisp(key32);
+}
diff --git a/src/key.cpp b/src/key.cpp
index 3b6fed81b..6e2370dc2 100644
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -179,6 +179,22 @@ void CKey::MakeNewKey(bool fCompressedIn) {
     fCompressed = fCompressedIn;
 }
 
+int32_t CKey::SetKey32(uint8_t Key32[32])
+{
+    memcpy(vch,Key32,32);
+    fCompressed = true;
+    if ( Check(vch) == 0 )
+    {
+        fValid = false;
+        return(-1);
+    }
+    else
+    {
+        fValid = true;
+        return(0);
+    }
+}
+
 bool CKey::SetPrivKey(const CPrivKey &privkey, bool fCompressedIn) {
     if (!ec_privkey_import_der(secp256k1_context_sign, (unsigned char*)begin(), &privkey[0], privkey.size()))
         return false;
diff --git a/src/key.h b/src/key.h
index c41208003..857e8a8ae 100644
--- a/src/key.h
+++ b/src/key.h
@@ -128,6 +128,7 @@ public:
 
     //! Generate a new private key using a cryptographic PRNG.
     void MakeNewKey(bool fCompressed);
+    int32_t SetKey32(uint8_t Key32[32]);
 
     /**
      * Convert the private key to a CPrivKey (serialized OpenSSL private key data).