134 lines
4 KiB
C++
134 lines
4 KiB
C++
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#include "stdafx.h"
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#include "password.h"
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// password categories
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enum {STRONG_PWD_UPPER=0,STRONG_PWD_LOWER,STRONG_PWD_NUM,STRONG_PWD_PUNC};
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#define STRONG_PWD_CATS (STRONG_PWD_PUNC + 1)
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#define NUM_LETTERS 26
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#define NUM_NUMBERS 10
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#define MIN_PWD_LEN 8
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// password must contain at least one each of:
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// uppercase, lowercase, punctuation and numbers
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DWORD CreateGoodPassword(BYTE *szPwd, DWORD dwLen)
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{
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if (dwLen-1 < MIN_PWD_LEN)
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{
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return ERROR_PASSWORD_RESTRICTION;
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}
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HCRYPTPROV hProv;
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DWORD dwErr = 0;
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if (CryptAcquireContext(&hProv,NULL,NULL,PROV_RSA_FULL,CRYPT_VERIFYCONTEXT) == FALSE)
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{
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return GetLastError();
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}
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// zero it out and decrement the size to allow for trailing '\0'
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ZeroMemory(szPwd,dwLen);
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dwLen--;
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// generate a pwd pattern, each byte is in the range
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// (0..255) mod STRONG_PWD_CATS
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// this indicates which character pool to take a char from
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BYTE *pPwdPattern = new BYTE[dwLen];
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BOOL fFound[STRONG_PWD_CATS];
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do
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{
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// bug!bug! does CGR() ever fail?
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CryptGenRandom(hProv,dwLen,pPwdPattern);
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fFound[STRONG_PWD_UPPER] =
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fFound[STRONG_PWD_LOWER] =
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fFound[STRONG_PWD_PUNC] =
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fFound[STRONG_PWD_NUM] = FALSE;
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for (DWORD i=0; i < dwLen; i++)
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{
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fFound[pPwdPattern[i] % STRONG_PWD_CATS] = TRUE;
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}
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// check that each character category is in the pattern
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} while (!fFound[STRONG_PWD_UPPER] || !fFound[STRONG_PWD_LOWER] || !fFound[STRONG_PWD_PUNC] || !fFound[STRONG_PWD_NUM]);
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// populate password with random data
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// this, in conjunction with pPwdPattern, is
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// used to determine the actual data
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CryptGenRandom(hProv,dwLen,szPwd);
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for (DWORD i=0; i < dwLen; i++)
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{
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BYTE bChar = 0;
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// there is a bias in each character pool because of the % function
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switch (pPwdPattern[i] % STRONG_PWD_CATS)
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{
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case STRONG_PWD_UPPER : bChar = 'A' + szPwd[i] % NUM_LETTERS;
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break;
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case STRONG_PWD_LOWER : bChar = 'a' + szPwd[i] % NUM_LETTERS;
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break;
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case STRONG_PWD_NUM : bChar = '0' + szPwd[i] % NUM_NUMBERS;
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break;
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case STRONG_PWD_PUNC :
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default:
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char *szPunc="!@#$%^&*()_-+=[{]};:\'\"<>,./?\\|~`";
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DWORD dwLenPunc = lstrlenA(szPunc);
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bChar = szPunc[szPwd[i] % dwLenPunc];
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break;
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}
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szPwd[i] = bChar;
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}
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delete pPwdPattern;
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if (hProv != NULL)
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{
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CryptReleaseContext(hProv,0);
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}
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return dwErr;
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}
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// Creates a secure password
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// caller must GlobalFree Return pointer
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// iSize = size of password to create
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LPTSTR CreatePassword(int iSize)
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{
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LPTSTR pszPassword = NULL;
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BYTE *szPwd = new BYTE[iSize];
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DWORD dwPwdLen = iSize;
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int i = 0;
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// use the new secure password generator
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// unfortunately this baby doesn't use unicode.
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// so we'll call it and then convert it to unicode afterwards.
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if (0 == CreateGoodPassword(szPwd,dwPwdLen))
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{
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#if defined(UNICODE) || defined(_UNICODE)
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// convert it to unicode and copy it back into our unicode buffer.
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// compute the length
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i = MultiByteToWideChar(CP_ACP, 0, (LPSTR) szPwd, -1, NULL, 0);
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if (i <= 0)
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{goto CreatePassword_Exit;}
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pszPassword = (LPTSTR) GlobalAlloc(GPTR, i * sizeof(TCHAR));
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if (!pszPassword)
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{goto CreatePassword_Exit;}
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i = MultiByteToWideChar(CP_ACP, 0, (LPSTR) szPwd, -1, pszPassword, i);
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if (i <= 0)
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{
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GlobalFree(pszPassword);
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pszPassword = NULL;
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goto CreatePassword_Exit;
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}
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// make sure ends with null
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pszPassword[i - 1] = 0;
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#else
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pszPassword = (LPSTR) GlobalAlloc(GPTR, _tcslen((LPTSTR) szPwd) * sizeof(TCHAR));
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#endif
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}
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CreatePassword_Exit:
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if (szPwd){delete szPwd;szPwd=NULL;}
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return pszPassword;
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}
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