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This is the format for save the passwords in modern Windows. The hash length are 128 bits and work for local account and Domain account (Active Directory account).
Parameter: Message which is the string to hash.
Output: Hash value which is a 128 bits value(4 integers of 32 bits).
Modern computer perform at 10 millions of NTLM hash/sec aprox. Some calculations:
There are 95 characters printable(this are almost all used in passwords).
With length = 7: 957/107 = 81 days
Lower case letter and numbers are 36.
With length = 8: 368/107 = 3.3 days
Lower case letter are 26.
With length = 9: 269/107 = 6.3 days
This simple calculations means that a NTLM secure password need to be at least 10 character length.
You could look a Perl implementation in theAuthen::Passphrase::NTHash module of CPAN.
/* Written by Alain Espinosa <alainesp@gmail.com> in 2008 and placed in the public domain. This file contain 4 functions: 1- prepare_key: which take the string to hash and convert to Unicode and apply the padding rule of MD4. This is save in nt_buffer variable. 2- ntlm_crypt: which take the nt_buffer and apply the compress function of MD4. 3- convert_hex: which convert the binary output in hexadecimal string. The same format that exist in John the Ripper files. 4- main: an example of use. The output are in the variable output or in hex_format if you like this one. Notes: - the mayor length of the key its 27 character. This is a restriction of this implementation and its very simple to bypass. */ #include <string.h> #include <stdio.h> //Init values #define INIT_A 0x67452301 #define INIT_B 0xefcdab89 #define INIT_C 0x98badcfe #define INIT_D 0x10325476 #define SQRT_2 0x5a827999 #define SQRT_3 0x6ed9eba1 unsigned int nt_buffer[16]; unsigned int output[4]; char hex_format[33]; char itoa16[16] = "0123456789abcdef"; //This is the MD4 compress function static void ntlm_crypt() { unsigned int a = INIT_A; unsigned int b = INIT_B; unsigned int c = INIT_C; unsigned int d = INIT_D; /* Round 1 */ a += (d ^ (b & (c ^ d))) + nt_buffer[0] ;a = (a << 3 ) | (a >> 29); d += (c ^ (a & (b ^ c))) + nt_buffer[1] ;d = (d << 7 ) | (d >> 25); c += (b ^ (d & (a ^ b))) + nt_buffer[2] ;c = (c << 11) | (c >> 21); b += (a ^ (c & (d ^ a))) + nt_buffer[3] ;b = (b << 19) | (b >> 13); a += (d ^ (b & (c ^ d))) + nt_buffer[4] ;a = (a << 3 ) | (a >> 29); d += (c ^ (a & (b ^ c))) + nt_buffer[5] ;d = (d << 7 ) | (d >> 25); c += (b ^ (d & (a ^ b))) + nt_buffer[6] ;c = (c << 11) | (c >> 21); b += (a ^ (c & (d ^ a))) + nt_buffer[7] ;b = (b << 19) | (b >> 13); a += (d ^ (b & (c ^ d))) + nt_buffer[8] ;a = (a << 3 ) | (a >> 29); d += (c ^ (a & (b ^ c))) + nt_buffer[9] ;d = (d << 7 ) | (d >> 25); c += (b ^ (d & (a ^ b))) + nt_buffer[10] ;c = (c << 11) | (c >> 21); b += (a ^ (c & (d ^ a))) + nt_buffer[11] ;b = (b << 19) | (b >> 13); a += (d ^ (b & (c ^ d))) + nt_buffer[12] ;a = (a << 3 ) | (a >> 29); d += (c ^ (a & (b ^ c))) + nt_buffer[13] ;d = (d << 7 ) | (d >> 25); c += (b ^ (d & (a ^ b))) + nt_buffer[14] ;c = (c << 11) | (c >> 21); b += (a ^ (c & (d ^ a))) + nt_buffer[15] ;b = (b << 19) | (b >> 13); /* Round 2 */ a += ((b & (c | d)) | (c & d)) + nt_buffer[0] +SQRT_2; a = (a<<3 ) | (a>>29); d += ((a & (b | c)) | (b & c)) + nt_buffer[4] +SQRT_2; d = (d<<5 ) | (d>>27); c += ((d & (a | b)) | (a & b)) + nt_buffer[8] +SQRT_2; c = (c<<9 ) | (c>>23); b += ((c & (d | a)) | (d & a)) + nt_buffer[12]+SQRT_2; b = (b<<13) | (b>>19); a += ((b & (c | d)) | (c & d)) + nt_buffer[1] +SQRT_2; a = (a<<3 ) | (a>>29); d += ((a & (b | c)) | (b & c)) + nt_buffer[5] +SQRT_2; d = (d<<5 ) | (d>>27); c += ((d & (a | b)) | (a & b)) + nt_buffer[9] +SQRT_2; c = (c<<9 ) | (c>>23); b += ((c & (d | a)) | (d & a)) + nt_buffer[13]+SQRT_2; b = (b<<13) | (b>>19); a += ((b & (c | d)) | (c & d)) + nt_buffer[2] +SQRT_2; a = (a<<3 ) | (a>>29); d += ((a & (b | c)) | (b & c)) + nt_buffer[6] +SQRT_2; d = (d<<5 ) | (d>>27); c += ((d & (a | b)) | (a & b)) + nt_buffer[10]+SQRT_2; c = (c<<9 ) | (c>>23); b += ((c & (d | a)) | (d & a)) + nt_buffer[14]+SQRT_2; b = (b<<13) | (b>>19); a += ((b & (c | d)) | (c & d)) + nt_buffer[3] +SQRT_2; a = (a<<3 ) | (a>>29); d += ((a & (b | c)) | (b & c)) + nt_buffer[7] +SQRT_2; d = (d<<5 ) | (d>>27); c += ((d & (a | b)) | (a & b)) + nt_buffer[11]+SQRT_2; c = (c<<9 ) | (c>>23); b += ((c & (d | a)) | (d & a)) + nt_buffer[15]+SQRT_2; b = (b<<13) | (b>>19); /* Round 3 */ a += (d ^ c ^ b) + nt_buffer[0] + SQRT_3; a = (a << 3 ) | (a >> 29); d += (c ^ b ^ a) + nt_buffer[8] + SQRT_3; d = (d << 9 ) | (d >> 23); c += (b ^ a ^ d) + nt_buffer[4] + SQRT_3; c = (c << 11) | (c >> 21); b += (a ^ d ^ c) + nt_buffer[12] + SQRT_3; b = (b << 15) | (b >> 17); a += (d ^ c ^ b) + nt_buffer[2] + SQRT_3; a = (a << 3 ) | (a >> 29); d += (c ^ b ^ a) + nt_buffer[10] + SQRT_3; d = (d << 9 ) | (d >> 23); c += (b ^ a ^ d) + nt_buffer[6] + SQRT_3; c = (c << 11) | (c >> 21); b += (a ^ d ^ c) + nt_buffer[14] + SQRT_3; b = (b << 15) | (b >> 17); a += (d ^ c ^ b) + nt_buffer[1] + SQRT_3; a = (a << 3 ) | (a >> 29); d += (c ^ b ^ a) + nt_buffer[9] + SQRT_3; d = (d << 9 ) | (d >> 23); c += (b ^ a ^ d) + nt_buffer[5] + SQRT_3; c = (c << 11) | (c >> 21); b += (a ^ d ^ c) + nt_buffer[13] + SQRT_3; b = (b << 15) | (b >> 17); a += (d ^ c ^ b) + nt_buffer[3] + SQRT_3; a = (a << 3 ) | (a >> 29); d += (c ^ b ^ a) + nt_buffer[11] + SQRT_3; d = (d << 9 ) | (d >> 23); c += (b ^ a ^ d) + nt_buffer[7] + SQRT_3; c = (c << 11) | (c >> 21); b += (a ^ d ^ c) + nt_buffer[15] + SQRT_3; b = (b << 15) | (b >> 17); output[0] = a + INIT_A; output[1] = b + INIT_B; output[2] = c + INIT_C; output[3] = d + INIT_D; } //This include the Unicode conversion and the padding static void prepare_key(char *key) { int i=0; int length=strlen(key); memset(nt_buffer,0,16*4); //The length of key need to be <= 27 for(;i<length/2;i++) nt_buffer[i] = key[2*i] | (key[2*i+1]<<16); //padding if(length%2==1) nt_buffer[i] = key[length-1] | 0x800000; else nt_buffer[i]=0x80; //put the length nt_buffer[14] = length << 4; } //This convert the output to hexadecimal form static void convert_hex() { int i=0; //Iterate the integer for(;i<4;i++) { int j=0; unsigned int n=output[i]; //iterate the bytes of the integer for(;j<4;j++) { unsigned int convert=n%256; hex_format[i*8+j*2+1]=itoa16[convert%16]; convert=convert/16; hex_format[i*8+j*2+0]=itoa16[convert%16]; n=n/256; } } //null terminate the string hex_format[33]=0; } //Sample main int main() { prepare_key("password"); ntlm_crypt(); convert_hex(); printf(hex_format); }