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<h1>Choosing Passwords and Keyfiles</h1>
<p>It is very important that you choose a good password. You must avoid choosing one that contains only a single word that can be found in a dictionary (or a combination of such words). It must not contain any names, dates of birth, account numbers, or any
 other items that could be easy to guess. A good password is a random combination of upper and lower case letters, numbers, and special characters, such as @ ^ = $ * &#43; etc. We strongly recommend choosing a password consisting of more than 20 characters (the
 longer, the better). Short passwords are easy to crack using brute-force techniques.<br>
<br>
To make brute-force attacks on a keyfile infeasible, the size of the keyfile must be at least 30 bytes. If a volume uses multiple keyfiles, then at least one of the keyfiles must be 30 bytes in size or larger. Note that the 30-byte limit assumes a large amount
 of entropy in the keyfile. If the first 1024 kilobytes of a file contain only a small amount of entropy, it must not be used as a keyfile (regardless of the file size). If you are not sure what entropy means, we recommend that you let VeraCrypt generate a
 file with random content and that you use it as a keyfile (select <em>Tools -&gt; Keyfile Generator</em>).</p>
<p>When creating a volume, encrypting a system partition/drive, or changing passwords/keyfiles, you must not allow any third party to choose or modify the password/keyfile(s) before/while the volume is created or the password/keyfiles(s) changed. For example,
 you must not use any password generators (whether website applications or locally run programs) where you are not sure that they are high-quality and uncontrolled by an attacker, and keyfiles must not be files that you download from the internet or that are
 accessible to other users of the computer (whether they are administrators or not).</p>
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="p">, input); return 1; } #else #ifndef CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY #if defined(__cplusplus) extern "C" { #endif typedef void (*SigHandler)(int); static jmp_buf s_jmpNoCPUID; static void SigIllHandlerCPUID(int p) { longjmp(s_jmpNoCPUID, 1); } #if !defined (_UEFI) && ((defined(__AES__) && defined(__PCLMUL__)) || defined(__INTEL_COMPILER) || CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE) static jmp_buf s_jmpNoAESNI; static void SigIllHandlerAESNI(int p) { longjmp(s_jmpNoAESNI, 1); } #endif #if CRYPTOPP_BOOL_X64 == 0 static jmp_buf s_jmpNoSSE2; static void SigIllHandlerSSE2(int p) { longjmp(s_jmpNoSSE2, 1); } #endif #if defined(__cplusplus) } #endif #endif int CpuId(uint32 input, uint32 output[4]) { #ifdef CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY #ifndef _UEFI __try { #endif __asm { mov eax, input mov ecx, 0 cpuid mov edi, output mov [edi], eax mov [edi+4], ebx mov [edi+8], ecx mov [edi+12], edx } #ifndef _UEFI } __except (EXCEPTION_EXECUTE_HANDLER) { return 0; } #endif // function 0 returns the highest basic function understood in EAX if(input == 0) return !!output[0]? 1 : 0; return 1; #else // longjmp and clobber warnings. Volatile is required. // http://github.com/weidai11/cryptopp/issues/24 // http://stackoverflow.com/q/7721854 volatile int result = 1; SigHandler oldHandler = signal(SIGILL, SigIllHandlerCPUID); if (oldHandler == SIG_ERR) result = 0; if (setjmp(s_jmpNoCPUID)) result = 0; else { asm volatile ( // save ebx in case -fPIC is being used // TODO: this might need an early clobber on EDI. #if CRYPTOPP_BOOL_X32 || CRYPTOPP_BOOL_X64 "pushq %%rbx; cpuid; mov %%ebx, %%edi; popq %%rbx" #else "push %%ebx; cpuid; mov %%ebx, %%edi; pop %%ebx" #endif : "=a" (output[0]), "=D" (output[1]), "=c" (output[2]), "=d" (output[3]) : "a" (input), "c" (0) ); } signal(SIGILL, oldHandler); return result; #endif } #endif static int TrySSE2() { #if CRYPTOPP_BOOL_X64 return 1; #elif defined(CRYPTOPP_MS_STYLE_INLINE_ASSEMBLY) && !defined(_UEFI) volatile int result = 1; #if defined (TC_WINDOWS_DRIVER) && !defined (_WIN64) KFLOATING_SAVE floatingPointState; if (NT_SUCCESS (KeSaveFloatingPointState (&floatingPointState))) { #endif __try { #if CRYPTOPP_BOOL_SSE2_ASM_AVAILABLE AS2(por xmm0, xmm0) // executing SSE2 instruction #elif CRYPTOPP_BOOL_SSE2_INTRINSICS_AVAILABLE __m128i x = _mm_setzero_si128(); result = _mm_cvtsi128_si32(x) == 0 ? 1 : 0; #endif } __except (EXCEPTION_EXECUTE_HANDLER) { result = 0; } #if defined (TC_WINDOWS_DRIVER) && !defined (_WIN64) KeRestoreFloatingPointState (&floatingPointState); } else return 0; #endif return result; #elif !defined(_UEFI) // longjmp and clobber warnings. Volatile is required. // http://github.com/weidai11/cryptopp/issues/24 // http://stackoverflow.com/q/7721854 volatile int result = 1; SigHandler oldHandler = signal(SIGILL, SigIllHandlerSSE2); if (oldHandler == SIG_ERR) return 0; if (setjmp(s_jmpNoSSE2)) result = 1; else { #if CRYPTOPP_BOOL_SSE2_ASM_AVAILABLE __asm __volatile ("por %xmm0, %xmm0"); #elif CRYPTOPP_BOOL_SSE2_INTRINSICS_AVAILABLE __m128i x = _mm_setzero_si128(); result = _mm_cvtsi128_si32(x) == 0? 1 : 0; #endif } signal(SIGILL, oldHandler); return result; #else return 1; #endif } int g_x86DetectionDone = 0; int g_hasISSE = 0, g_hasSSE2 = 0, g_hasSSSE3 = 0, g_hasMMX = 0, g_hasAESNI = 0, g_hasCLMUL = 0, g_isP4 = 0; int g_hasAVX = 0, g_hasSSE42 = 0, g_hasSSE41 = 0; uint32 g_cacheLineSize = CRYPTOPP_L1_CACHE_LINE_SIZE; VC_INLINE int IsIntel(const uint32 output[4]) { // This is the "GenuineIntel" string return (output[1] /*EBX*/ == 0x756e6547) && (output[2] /*ECX*/ == 0x6c65746e) && (output[3] /*EDX*/ == 0x49656e69); } VC_INLINE int IsAMD(const uint32 output[4]) { // This is the "AuthenticAMD" string return (output[1] /*EBX*/ == 0x68747541) && (output[2] /*ECX*/ == 0x69746E65) && (output[3] /*EDX*/ == 0x444D4163); } #if !defined (_UEFI) && ((defined(__AES__) && defined(__PCLMUL__)) || defined(__INTEL_COMPILER) || CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE) static int TryAESNI () { volatile int result = 0; #ifdef _MSC_VER __try #else SigHandler oldHandler = signal(SIGILL, SigIllHandlerAESNI); if (oldHandler == SIG_ERR) return 0; if (setjmp(s_jmpNoAESNI)) result = 0; else #endif { __m128i block, subkey, ciphered; // perform AES round. block = _mm_setr_epi32(0x11223344,0x55667788,0x99AABBCC,0xDDEEFF00); subkey = _mm_setr_epi32(0xA5A5A5A5,0xA5A5A5A5,0x5A5A5A5A,0x5A5A5A5A); ciphered = _mm_aesenc_si128(block, subkey); #ifdef _MSC_VER if (ciphered.m128i_u64[0] == LL(0x2f4654b9485061fa) && ciphered.m128i_u64[1] == LL(0xc8b51f1fe1256f99)) #else if (((uint64_t*)(&ciphered))[0] == LL(0x2f4654b9485061fa) && ((uint64_t*)(&ciphered))[1] == LL(0xc8b51f1fe1256f99)) #endif result = 1; } #ifdef _MSC_VER __except (EXCEPTION_EXECUTE_HANDLER) { // ignore error if AES-NI not supported } #else signal(SIGILL, oldHandler); #endif return result; } static int Detect_MS_HyperV_AES () { int hasAesNI = 0; // when Hyper-V is enabled on older versions of Windows Server (i.e. 2008 R2), the AES-NI capability // gets masked out for all applications, even running on the host. // We try to detect Hyper-V virtual CPU and perform a dummy AES-NI operation to check its real presence uint32 cpuid[4]; char HvProductName[13]; CpuId(0x40000000, cpuid); memcpy (HvProductName, &cpuid[1], 12); HvProductName[12] = 0; if (_stricmp(HvProductName, "Microsoft Hv") == 0) { #if defined (TC_WINDOWS_DRIVER) && !defined (_WIN64) KFLOATING_SAVE floatingPointState; if (NT_SUCCESS (KeSaveFloatingPointState (&floatingPointState))) { #endif hasAesNI = TryAESNI (); #if defined (TC_WINDOWS_DRIVER) && !defined (_WIN64) KeRestoreFloatingPointState (&floatingPointState); } #endif } return hasAesNI; } #endif void DetectX86Features() { uint32 cpuid[4] = {0}, cpuid1[4] = {0}; if (!CpuId(0, cpuid)) return; if (!CpuId(1, cpuid1)) return; g_hasMMX = (cpuid1[3] & (1 << 23)) != 0; if ((cpuid1[3] & (1 << 26)) != 0) g_hasSSE2 = TrySSE2(); g_hasAVX = g_hasSSE2 && (cpuid1[2] & (1 << 28)); g_hasSSE42 = g_hasSSE2 && (cpuid1[2] & (1 << 20)); g_hasSSE41 = g_hasSSE2 && (cpuid1[2] & (1 << 19)); g_hasSSSE3 = g_hasSSE2 && (cpuid1[2] & (1<<9)); g_hasAESNI = g_hasSSE2 && (cpuid1[2] & (1<<25)); g_hasCLMUL = g_hasSSE2 && (cpuid1[2] & (1<<1)); #if !defined (_UEFI) && ((defined(__AES__) && defined(__PCLMUL__)) || defined(__INTEL_COMPILER) || CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE) // Hypervisor = bit 31 of ECX of CPUID leaf 0x1 // reference: http://artemonsecurity.com/vmde.pdf if (!g_hasAESNI && (cpuid1[2] & (1<<31))) { g_hasAESNI = Detect_MS_HyperV_AES (); } #endif if ((cpuid1[3] & (1 << 25)) != 0) g_hasISSE = 1; else { uint32 cpuid2[4]; CpuId(0x080000000, cpuid2); if (cpuid2[0] >= 0x080000001) { CpuId(0x080000001, cpuid2); g_hasISSE = (cpuid2[3] & (1 << 22)) != 0; } } if (IsIntel(cpuid)) { g_isP4 = ((cpuid1[0] >> 8) & 0xf) == 0xf; g_cacheLineSize = 8 * GETBYTE(cpuid1[1], 1); } else if (IsAMD(cpuid)) { CpuId(0x80000005, cpuid); g_cacheLineSize = GETBYTE(cpuid[2], 0); } if (!g_cacheLineSize) g_cacheLineSize = CRYPTOPP_L1_CACHE_LINE_SIZE; *((volatile int*)&g_x86DetectionDone) = 1; } int is_aes_hw_cpu_supported () { int bHasAESNI = 0; uint32 cpuid[4]; if (CpuId(1, cpuid)) { if (cpuid[2] & (1<<25)) bHasAESNI = 1; #if !defined (_UEFI) && ((defined(__AES__) && defined(__PCLMUL__)) || defined(__INTEL_COMPILER) || CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE) // Hypervisor = bit 31 of ECX of CPUID leaf 0x1 // reference: http://artemonsecurity.com/vmde.pdf if (!bHasAESNI && (cpuid[2] & (1<<31))) { bHasAESNI = Detect_MS_HyperV_AES (); } #endif } return bHasAESNI; } #endif