MD5 message digest conversion to 16 byte array

[chaitali.pats]

Hi ,

I have implemented MD5 in C language . I am getting an output of 32
bits Hexadecimal number . for example :

83a80d3ca057492 f0ce99ac1db8dce d0

I need to convert this string same to 16 byte array.
Can anyone help me ?

Thanks a lot !!!
Chaitali

[Skarmander]

ch***********@g mail.com wrote:

Hi ,

I have implemented MD5 in C language . I am getting an output of 32
bits Hexadecimal number . for example :

83a80d3ca057492 f0ce99ac1db8dce d0
That's not a 32-bit hexadecimal number by any interpretation of that phrase;
that's a string.
I need to convert this string same to 16 byte array.
If you actually implemented MD5, it's not likely that you want this. You can
change the code that produces the string above to output a byte array instead.

If, on the other hand, you're writing a function that has to take a string
like this and turn it into a byte array, that's a different matter.
Can anyone help me ?

Since your question does not appear to involve anything that's C specific
and doesn't include any code, it's rather hard to help you.

MD5 is a very common algorithm. Have you tried checking whether Google is
your friend in this case?

S.

[chaitali.pats]

Thanks .
Sorry for putting an incomplete question .
Actually you are right . I need to convert this string to byte array .
Can you help me how to convert the string into byte array because I
think there is some padding issues involved in the conversion,

Skarmander wrote:

ch***********@g mail.com wrote:

Hi ,

I have implemented MD5 in C language . I am getting an output of 32
bits Hexadecimal number . for example :

83a80d3ca057492 f0ce99ac1db8dce d0

That's not a 32-bit hexadecimal number by any interpretation of that phrase;
that's a string.

I need to convert this string same to 16 byte array.

If you actually implemented MD5, it's not likely that you want this. You can
change the code that produces the string above to output a byte array instead.

If, on the other hand, you're writing a function that has to take a string
like this and turn it into a byte array, that's a different matter.

Can anyone help me ?

Since your question does not appear to involve anything that's C specific
and doesn't include any code, it's rather hard to help you.

MD5 is a very common algorithm. Have you tried checking whether Google is
your friend in this case?

S.

[Neil]

ch***********@g mail.com wrote:

Thanks .
Sorry for putting an incomplete question .
Actually you are right . I need to convert this string to byte array .
Can you help me how to convert the string into byte array because I
think there is some padding issues involved in the conversion,

Skarmander wrote:

ch***********@g mail.com wrote:

Hi ,

I have implemented MD5 in C language . I am getting an output of 32
bits Hexadecimal number . for example :

83a80d3ca057492 f0ce99ac1db8dce d0

That's not a 32-bit hexadecimal number by any interpretation of that phrase;
that's a string.

I need to convert this string same to 16 byte array.

If you actually implemented MD5, it's not likely that you want this. You can
change the code that produces the string above to output a byte array instead.

If, on the other hand, you're writing a function that has to take a string
like this and turn it into a byte array, that's a different matter.

Can anyone help me ?

Since your question does not appear to involve anything that's C specific
and doesn't include any code, it's rather hard to help you.

MD5 is a very common algorithm. Have you tried checking whether Google is
your friend in this case?

S.

There are may ways.
one is to make the array 0123456789ABCDE ( match the case to you input)

start from the MSD find the char in the array add the position to total.
mult by 16 and move to the next digit.

Starting from the LSD you will need to use a multiplier variable.

[Chris McDonald]

ch***********@g mail.com writes:

Thanks .
Sorry for putting an incomplete question .
Actually you are right . I need to convert this string to byte array .
Can you help me how to convert the string into byte array because I
think there is some padding issues involved in the conversion,

I find it extremely difficult to believe that you've been able to
(correctly) implement the MD5 algorithm, but are unable to convert a
string input to a byte array. Anyway, I could be wrong, so, good luck
with your problem.

--
Chris.

[Tom St Denis]

Chris McDonald wrote:

ch***********@g mail.com writes:

Thanks .
Sorry for putting an incomplete question .
Actually you are right . I need to convert this string to byte array .
Can you help me how to convert the string into byte array because I
think there is some padding issues involved in the conversion,

I find it extremely difficult to believe that you've been able to
(correctly) implement the MD5 algorithm, but are unable to convert a
string input to a byte array. Anyway, I could be wrong, so, good luck
with your problem.

Are you <SHOCK> suggesting that they randomly picked up code off the
web and pasted it into their application without really knowing what
they are doing?

It's almost as if people should write pre-packaged bodies, if not in
the form of a library, of cryptographic algorithms and protocols for
just such an occasion. That it should ALSO be accessible by some form
of web page searching function, almost like a web search.

:-)

Tom

[Skarmander]

ch***********@g mail.com wrote:

Skarmander wrote:

ch***********@g mail.com wrote:

Hi ,

I have implemented MD5 in C language . I am getting an output of 32
bits Hexadecimal number . for example :

83a80d3ca057492 f0ce99ac1db8dce d0

That's not a 32-bit hexadecimal number by any interpretation of that phrase;
that's a string.

I need to convert this string same to 16 byte array.

If you actually implemented MD5, it's not likely that you want this. You can
change the code that produces the string above to output a byte array instead.

If, on the other hand, you're writing a function that has to take a string
like this and turn it into a byte array, that's a different matter.

Can anyone help me ?

Since your question does not appear to involve anything that's C specific
and doesn't include any code, it's rather hard to help you.

MD5 is a very common algorithm. Have you tried checking whether Google is
your friend in this case?

Thanks .
Sorry for putting an incomplete question .
Actually you are right . I need to convert this string to byte array .
Can you help me how to convert the string into byte array because I
think there is some padding issues involved in the conversion,

Don't top-post, please. Put your reply at the bottom.

There are no padding issues involved if you are always converting an even
number of hexadecimal digits into a contiguous sequence of bytes.

The function you'll be writing will look something like this:

void hexstring_to_by tes(const char *str, unsigned char *bytes, size_t
len) {
size_t n;
for (n = 0; n < len; n += 2) {
bytes[n / 2] = hexdigit_to_int (str[n]) * 16 +
hexdigit_to_int (str[n + 1]);
}
}

Figuring out how to properly call this function and writing
hexdigit_to_int () are left as exercises. Also, think about how to handle
improper input.

S.

[Default User]

ch***********@g mail.com wrote:

Thanks .

Please don't top-post. Your replies belong following or interspersed
with properly trimmed quotes. See the other 99% of the posts in this
group.


Brian

[chaitali.pats]

Tom St Denis wrote:

Chris McDonald wrote:

ch***********@g mail.com writes:

Thanks .
Sorry for putting an incomplete question .
Actually you are right . I need to convert this string to byte array .
Can you help me how to convert the string into byte array because I
think there is some padding issues involved in the conversion,

I find it extremely difficult to believe that you've been able to
(correctly) implement the MD5 algorithm, but are unable to convert a
string input to a byte array. Anyway, I could be wrong, so, good luck
with your problem.

Are you <SHOCK> suggesting that they randomly picked up code off the
web and pasted it into their application without really knowing what
they are doing?

It's almost as if people should write pre-packaged bodies, if not in
the form of a library, of cryptographic algorithms and protocols for
just such an occasion. That it should ALSO be accessible by some form
of web page searching function, almost like a web search.

:-)

Tom

I had tried everything . But it didn't work .
That's why thought of asking help .
anyway .. now i think i shouldn't have .

[chaitali.pats]

Skarmander wrote:

ch***********@g mail.com wrote:

Skarmander wrote:

ch***********@g mail.com wrote:
Hi ,

I have implemented MD5 in C language . I am getting an output of 32
bits Hexadecimal number . for example :

83a80d3ca057492 f0ce99ac1db8dce d0

That's not a 32-bit hexadecimal number by any interpretation of that phrase;
that's a string.

I need to convert this string same to 16 byte array.
If you actually implemented MD5, it's not likely that you want this. You can
change the code that produces the string above to output a byte array instead.

If, on the other hand, you're writing a function that has to take a string
like this and turn it into a byte array, that's a different matter.

Can anyone help me ?

Since your question does not appear to involve anything that's C specific
and doesn't include any code, it's rather hard to help you.

MD5 is a very common algorithm. Have you tried checking whether Google is
your friend in this case?

> Thanks .
> Sorry for putting an incomplete question .
> Actually you are right . I need to convert this string to byte array .
> Can you help me how to convert the string into byte array because I
> think there is some padding issues involved in the conversion,
>

Don't top-post, please. Put your reply at the bottom.

There are no padding issues involved if you are always converting an even
number of hexadecimal digits into a contiguous sequence of bytes.

The function you'll be writing will look something like this:

void hexstring_to_by tes(const char *str, unsigned char *bytes, size_t
len) {
size_t n;
for (n = 0; n < len; n += 2) {
bytes[n / 2] = hexdigit_to_int (str[n]) * 16 +
hexdigit_to_int (str[n + 1]);
}
}

Figuring out how to properly call this function and writing
hexdigit_to_int () are left as exercises. Also, think about how to handle
improper input.

S.

Thanks for your help . :-)