/* Command Line Password Generator for Windows and UNIX-like systems.
* Copyright (C) 2011 FireXware <firexware@gmail.com>
* https://defuse.ca/
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Compiling with Visual C++:
* cl.exe passgen.cpp advapi32.lib
* Compiling with G++:
* g++ passgen.cpp -o passgen
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef _WIN32
#include <windows.h>
#include <wincrypt.h>
#endif
#define PASSWORD_LENGTH 64
/*
* Fills 'buffer' with cryptographically secure random bytes.
* buffer - gets filled with random bytes.
* bufferlength - length of buffer
*/
bool getRandom(unsigned char* buffer, unsigned int bufferlength)
{
#ifdef _WIN32
HCRYPTPROV hCryptCtx = NULL;
CryptAcquireContext(&hCryptCtx, NULL, MS_DEF_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
if(hCryptCtx == NULL)
return false;
CryptGenRandom(hCryptCtx, bufferlength, buffer);
CryptReleaseContext(hCryptCtx, 0);
#else
FILE* random = fopen("/dev/random", "rb");
if(random == NULL)
return false;
unsigned int read = fread(buffer, sizeof(unsigned char), bufferlength, random);
if(read != bufferlength)
return false;
fclose(random);
#endif
return true;
}
void showHelp()
{
puts("Usage: passgen <type>");
puts("Where <type> is one of:");
puts("--hex 256 bit hex string");
puts("--ascii 64 character ascii printable string");
puts("--alpha 64 character alpha-numeric string");
puts("--help show this page");
}
inline unsigned char getMinimalBitMask(unsigned char toRepresent)
{
if(toRepresent <= 0x01)
return 0x01;
else if(toRepresent <= 0x03)
return 0x03;
else if(toRepresent <= 0x07)
return 0x07;
else if(toRepresent <= 0x0F)
return 0x0F;
else if(toRepresent <= 0x1F)
return 0x1F;
else if(toRepresent <= 0x3F)
return 0x3F;
else if(toRepresent <= 0x7F)
return 0x7F;
else
return 0xFF;
}
bool getPassword(char *set, unsigned char setLength, char *password, unsigned int passwordLength)
{
unsigned int bufLen = passwordLength;
int bufIdx = 0;
unsigned char *rndBuf = (unsigned char*)malloc(bufLen);
unsigned char bitMask = getMinimalBitMask(setLength - 1);
if(!getRandom(rndBuf, bufLen))
return false;
int i = 0;
while(i < passwordLength)
{
// Read more random bytes if necessary.
if(bufIdx >= bufLen)
{
if(!getRandom(rndBuf, bufLen))
return false;
bufIdx = 0;
}
unsigned char c = rndBuf[bufIdx++];
c = c & bitMask;
// Discard the random byte if it isn't in range.
if(c < setLength)
{
password[i] = set[c];
i++;
}
}
memset(rndBuf, 0xFF, bufLen);
free(rndBuf);
return true;
}
int main(int argc, char* argv[])
{
if(argc != 2)
{
showHelp();
return 1;
}
char set[255];
unsigned char setlength = 0;
if(strncmp(argv[1],"--help", 6) == 0)
{
showHelp();
return 0;
}
else if(strncmp(argv[1], "--ascii",5) == 0)
{
strcpy(set, "!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~");
setlength = 94;
}
else if(strncmp(argv[1], "--hex", 3) == 0)
{
strcpy(set, "ABCDEF0123456789");
setlength = 16;
}
else if(strncmp(argv[1], "--alpha", 5) == 0)
{
strcpy(set, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789");
setlength = 62;
}
else
{
showHelp();
return 1;
}
char result[PASSWORD_LENGTH];
puts("Getting random data...");
if(getPassword(set, setlength, result, PASSWORD_LENGTH))
{
for(int i = 0; i < PASSWORD_LENGTH; i++)
{
printf("%c", result[i]);
}
printf("\n");
}
else
{
fprintf(stderr, "Error getting random data.\n");
return 2;
}
memset(result, 0, PASSWORD_LENGTH);
return 0;
}
