MD5 hash calculation

Applications Programming
1

hi

i want to generate MD5 hash of string in unix (hp) i have the algorithm which takes file as argument and returns hash of file but when i tried to generate hash of "a" result was "60b725f10c9c85c70d97880dfe8191b3" hash but actually it should have been "0cc175b9c0f1b6a831c399e269772661" now i am not getting what is wrong here ???

is there any conversion required on string before giving to hash generator???
if yes in which form its required??

here is the main part of MD5.c

#ifdef TEST

#include <stdlib.h>
#include <stdio.h>

/*
 * those are the standard RFC 1321 test vectors
 */

static char *msg[] = 
{
    "",
    "a",
    "abc",
    "message digest",
    "abcdefghijklmnopqrstuvwxyz",
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
    "12345678901234567890123456789012345678901234567890123456789012" \
        "345678901234567890"
};

static char *val[] =
{
    "d41d8cd98f00b204e9800998ecf8427e",
    "0cc175b9c0f1b6a831c399e269772661",
    "900150983cd24fb0d6963f7d28e17f72",
    "f96b697d7cb7938d525a2f31aaf161d0",
    "c3fcd3d76192e4007dfb496cca67e13b",
    "d174ab98d277d9f5a5611c2c9f419d9f",
    "57edf4a22be3c955ac49da2e2107b67a"
};

int main( int argc, char *argv[] )
{
    FILE *f;
    int i, j;
    char output[33];
    md5_context ctx;
    unsigned char buf[1000];
    unsigned char md5sum[16];

    if( argc < 2 )
    {
        printf( "\n MD5 Validation Tests:\n\n" );

        for( i = 0; i < 7; i++ )
        {
            printf( " Test %d ", i + 1 );

            md5_starts( &ctx );
            md5_update( &ctx, (uint8 *) msg, strlen( msg ) );
            md5_finish( &ctx, md5sum );

            for( j = 0; j < 16; j++ )
            {
                sprintf( output + j * 2, "%02x", md5sum[j] );
            }

            if( memcmp( output, val, 32 ) )
            {
                printf( "failed!\n" );
                return( 1 );
            }

            printf( "passed.\n" );
        }

        printf( "\n" );
    }
    else
    {
        if( ! ( f = fopen( argv[1], "rb" ) ) )
        {
            perror( "fopen" );
            return( 1 );
        }

        md5_starts( &ctx );

        while( ( i = fread( buf, 1, sizeof( buf ), f ) ) > 0 )
        {
            md5_update( &ctx, buf, i );
        }

        md5_finish( &ctx, md5sum );

        for( j = 0; j < 16; j++ )
        {
            printf( "%02x", md5sum[j] );
        }

        printf( "  %s\n", argv[1] );
    }

    return( 0 );
}

#endif
2

I don't see md5.h being included. How does it know what a md5_context is?

3

this is not full program if u want i can give you..
its just a bottom part of program ...upper part contains complex calculation so i skipped that part ...

i can give u link from where i took this program.

4

Seems like a trailing newline (0x0a) sneaked in somewhere.

As you can see from this:

root@voiptest2:~# echo 'a' | md5sum
60b725f10c9c85c70d97880dfe8191b3  -
root@voiptest2:~# echo 'a' | hexdump -C
00000000  61 0a                                             |a.|
00000002
root@voiptest2:~# echo -n 'a' | md5sum
0cc175b9c0f1b6a831c399e269772661  -

So you took the code from Mbed TLS - Trusted Firmware, if you run the original self test, did you get the same result?

5

hey thanx man for your help the code at url you have mentioned is somewhat similar ..but that newline char worked man

$echo "message digest\c" >4
$a.out 4
f96b697d7cb7938d525a2f31aaf161d0 4
$

which is expected one.. now how can i write into file suppresing new line character because i am using md5 file to generate hash code with the input from cobol program so i need to have an intermediate function .....