OTCallback.hpp

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/************************************************************
 *
 *  OTCallback.hpp
 *
 */

/************************************************************
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 *                 OPEN TRANSACTIONS
 *
 *       Financial Cryptography and Digital Cash
 *       Library, Protocol, API, Server, CLI, GUI
 *
 *       -- Anonymous Numbered Accounts.
 *       -- Untraceable Digital Cash.
 *       -- Triple-Signed Receipts.
 *       -- Cheques, Vouchers, Transfers, Inboxes.
 *       -- Basket Currencies, Markets, Payment Plans.
 *       -- Signed, XML, Ricardian-style Contracts.
 *       -- Scripted smart contracts.
 *
 *  Copyright (C) 2010-2013 by "Fellow Traveler" (A pseudonym)
 *
 *  EMAIL:
 *  [email protected]
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 *  BITCOIN:  1NtTPVVjDsUfDWybS4BwvHpG2pdS9RnYyQ
 *
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 *  OFFICIAL PROJECT WIKI(s):
 *  https://github.com/FellowTraveler/Moneychanger
 *  https://github.com/FellowTraveler/Open-Transactions/wiki
 *
 *  WEBSITE:
 *  http://www.OpenTransactions.org/
 *
 *  Components and licensing:
 *   -- Moneychanger..A Java client GUI.....LICENSE:.....GPLv3
 *   -- otlib.........A class library.......LICENSE:...LAGPLv3
 *   -- otapi.........A client API..........LICENSE:...LAGPLv3
 *   -- opentxs/ot....Command-line client...LICENSE:...LAGPLv3
 *   -- otserver......Server Application....LICENSE:....AGPLv3
 *  Github.com/FellowTraveler/Open-Transactions/wiki/Components
 *
 *  All of the above OT components were designed and written by
 *  Fellow Traveler, with the exception of Moneychanger, which
 *  was contracted out to Vicky C ([email protected]).
 *  The open-source community has since actively contributed.
 *
 *  -----------------------------------------------------
 *
 *   LICENSE:
 *   This program is free software: you can redistribute it
 *   and/or modify it under the terms of the GNU Affero
 *   General Public License as published by the Free Software
 *   Foundation, either version 3 of the License, or (at your
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 *   don't have to open-source your code--only your changes to
 *   Open-Transactions itself must be open source. Similar to
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 *   Lucre License:
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 *   rie's license must also be included and respected, since
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 *   See Open-Transactions/src/otlib/lucre/LUCRE_LICENSE.txt
 *   The Laurie requirements are light, but if there is any
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 *   Although there are no other blind token algorithms in Open
 *   Transactions (yet. credlib is coming), the other functions
 *   will continue to operate.
 *   See Lucre on Github:  https://github.com/benlaurie/lucre
 *   -----------------------------------------------------
 *   You should have received a copy of the GNU Affero General
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 *   (Unfortunately many will run anonymously and untraceably,
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 *   DISCLAIMER:
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 *   PURPOSE.  See the GNU Affero General Public License for
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#ifndef OPENTXS_CORE_CRYPTO_OTCALLBACK_HPP
#define OPENTXS_CORE_CRYPTO_OTCALLBACK_HPP

namespace opentxs
{

class OTPassword;

/*
 To use:

 OTPassword thePass;
 (Or...)
 OTPassword thePass(strPassword, strPassword.length());

 const char * szPassword    = thePass.getPassword();
 const int32_t    nPassLength    = thePass.getPasswordSize();

 If the instance of OTPassword is not going to be destroyed immediately
 after the password is used, then make sure to call zeroMemory() after
 using the password. (Otherwise the destructor will handle this anyway.)

 (The primary purpose of this class is that it zeros its memory out when
 it is destructed.)

 This class gives me a safe way to hand-off a password, and off-load the
 handling risk to the user.  This class will be included as part of the
 OT-API SWIG interface so that it's available inside other languages.

 */

#define OT_PW_DISPLAY "Enter master passphrase for wallet."

#define OTPASSWORD_BLOCKSIZE 128 // (128 bytes max length for a password.)
#define OTPASSWORD_MEMSIZE 129   // +1 for null terminator.

// UPDATE: Increasing the size here, so we can accommodate private keys (in
// addition to passphrases.)
//
#define OT_LARGE_BLOCKSIZE 32767 // (32767 bytes max length for a password.)
#define OT_LARGE_MEMSIZE 32768   // +1 for null terminator.

// Default is the smaller size.
#define OT_DEFAULT_BLOCKSIZE 128
#define OT_DEFAULT_MEMSIZE 129

// https://github.com/lorf/keepassx/blob/master/src/lib/SecString.cpp

// Done:  Although we have good memory ZEROING code (for destruction)
// we don't have code yet that will keep the contents SECURE while they
// are in memory. For example, that will prevent them from being paged
// to the hard drive during swapping. Such code would make OTPassword much
// more appropriate for use cases such as storing passphrases and private
// keys, and would even allow timeout procedures...
//
// NOTE: For Windows, use VirtualLock instead of mlock.
//

/*
 #include <sys/mman.h>

 void *locking_alloc(size_t numbytes)
 {
    static short have_warned = 0;

    void *mem = malloc(numbytes);

    if (mlock(mem, numbytes) && !have_warned)
    {

        // We probably do not have permission.
        // Sometimes, it might not be possible to lock enough memory.

        fprintf(stderr, "Warning: Using insecure memory!\n");

        have_warned = 1;

    }

    return mem;
 }

The mlock() call generally locks more memory than you want. Locking is done on a
per-page basis. All of the pages the memory spans will be locked in RAM, and
will not be swapped out under any circumstances, until the process unlocks
something in the same page by using mlock().

There are some potentially negative consequences here. First, If your process
locks two buffers that happen to live on the same page, then unlocking either
one will unlock the entire page, causing both buffers to unlock. Second, when
locking lots of data, it is easy to lock more pages than necessary (the
operating system doesn't move data around once it has been allocated), which can
slow down machine performance significantly.

Unlocking a chunk of memory looks exactly the same as locking it, except that
you call munlock():
        munlock(mem, numbytes);


 // TODO: Work in some usage of CryptProtectMemory and CryptUnprotectMemory
(Windows only)
 // with sample code below.  Also should make some kind of UNIX version.


#ifndef _WINDOWS_
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#endif
#include <cstdio>
#include <Wincrypt.h>

#define SSN_STR_LEN 12  // includes null

void main()
{
    HRESULT hr = S_OK;
    LPWSTR pSensitiveText = nullptr;
    DWORD cbSensitiveText = 0;
    DWORD cbPlainText = SSN_STR_LEN*sizeof(WCHAR);
    DWORD dwMod = 0;

    //  Memory to encrypt must be a multiple of CRYPTPROTECTMEMORY_BLOCK_SIZE.
    if (dwMod = cbPlainText % CRYPTPROTECTMEMORY_BLOCK_SIZE)
        cbSensitiveText = cbPlainText +
        (CRYPTPROTECTMEMORY_BLOCK_SIZE - dwMod);
    else
        cbSensitiveText = cbPlainText;

    pSensitiveText = (LPWSTR)LocalAlloc(LPTR, cbSensitiveText);
    if (nullptr == pSensitiveText)
    {
        wprintf(L"Memory allocation failed.\n");
        return E_OUTOFMEMORY;
    }

    //  Place sensitive string to encrypt in pSensitiveText.

    if (!CryptProtectMemory(pSensitiveText, cbSensitiveText,
        CRYPTPROTECTMEMORY_SAME_PROCESS))
    {
        wprintf(L"CryptProtectMemory failed: %d\n", GetLastError());
        SecureZeroMemory(pSensitiveText, cbSensitiveText);
        LocalFree(pSensitiveText);
        pSensitiveText = nullptr;
        return E_FAIL;
    }

    //  Call CryptUnprotectMemory to decrypt and use the memory.

    SecureZeroMemory(pSensitiveText, cbSensitiveText);
    LocalFree(pSensitiveText);
    pSensitiveText = nullptr;

    return hr;
}




#ifndef _WINDOWS_
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#endif
#include <cstdio>
#include <Wincrypt.h>
#include <strsafe.h>
#pragma comment(lib, "crypt32.lib")

void main()
{
    LPWSTR pEncryptedText;  // contains the encrypted text
    DWORD cbEncryptedText;  // number of bytes to which
                            // pEncryptedText points

    if (CryptUnprotectMemory(pEncryptedText, cbEncryptedText,
        CRYPTPROTECTMEMORY_SAME_PROCESS))
    {
        // Use the decrypted string.
    }
    else
    {
        wprintf(L"CryptUnprotectMemory failed: %d\n",
            GetLastError());
    }

    // Clear and free memory after using
    // the decrypted string or if an error occurs.
    SecureZeroMemory(pEncryptedText, cbEncryptedText);
    LocalFree(pEncryptedText);
    pEncryptedText = nullptr;
}


 */

//#undef OTPASSWORD_BLOCKSIZE
//#undef OTPASSWORD_MEMSIZE
//
//#undef OT_LARGE_BLOCKSIZE
//#undef OT_LARGE_MEMSIZE
//
//#undef OT_DEFAULT_BLOCKSIZE
//#undef OT_DEFAULT_MEMSIZE

// Used for the password callback...
//
class OTCallback
{
public:
    OTCallback()
    {
    }
    EXPORT virtual ~OTCallback();

    // Asks for password once. (For authentication when using nym.)
    EXPORT virtual void runOne(const char* szDisplay,
                               OTPassword& theOutput) const;

    // Asks for password twice. (For confirmation when changing password or
    // creating nym.)
    EXPORT virtual void runTwo(const char* szDisplay,
                               OTPassword& theOutput) const;
};

} // namespace opentxs

#endif // OPENTXS_CORE_CRYPTO_OTCALLBACK_HPP