undefined reference to md5

Question

#include <openssl/md5.h>
void mMD5(unsigned char * packet, int size) {

    unsigned char* res;

    MD5((unsigned char*)&packet, size, (unsigned char*)&res);

    for(int i=0; i<MD5_DIGEST_LENGTH; i++) {
        printf("%02x", res[i]);
    }
}

I get the error: undefined reference to MD5

Can anyone help me?

Answered in http://stackoverflow.com/questions/1894013/how-to-use-openssl-in-gcc — csl, Mar 20 '12 at 19:26

score 13 · Accepted Answer · answered Mar 20 '12 at 19:25

13

You need to link to the matching library. You should have a file called md5.lib or md5.a or something like that (depending on your OS), and add it to your linker command line (again, depending on your environment).

answered Mar 20 '12 at 19:25

Asaf

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13

In gcc, it's `-lssl -lcrypto`. – csl Mar 20 '12 at 19:26
thanks ! it work't! But, do you know how to put set the link options in eclipse? – Bewn Mar 20 '12 at 19:47
I don't really use eclipse, but I imagine you should find it somewhere in the workspace's linker options (or something like that). – Asaf Mar 20 '12 at 20:04
Many thanks my friend! I found how to do it in eclipse to. :) – Bewn Mar 21 '12 at 21:25
Would you know how it is for PostgreSQL? I am having the same problem while writing C code for MD5 in PSQL. But the answer does not help. – student001 Apr 11 '14 at 09:01
For those who are looking to do this in eclipse, it's Right Click Project -> C/C++ Build Settings -> Tool Settings -> GCC C Linker -> Libraries and then add ssl and crypto in the -l section on the right. – stanri Jun 02 '16 at 08:11

undefined reference to md5

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