How to gen 32bytes hex string by openssl

This is a discussion on How to gen 32bytes hex string by openssl within the C Programming forums, part of the General Programming Boards category; Hi all, How to gen 32bytes hex string by openssl, I try to use RAND_byte, which is not in hex ...

  1. #1
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    How to gen 32bytes hex string by openssl

    Hi all, How to gen 32bytes hex string by openssl, I try to use RAND_byte, which is not in hex format, many thanks!!

  2. #2
    - - - - - - - - oogabooga's Avatar
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    What do you mean by "not in hex format"? Do you have some example code and output?
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

  3. #3
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    for example:
    unsigned char key[49];
    RAND_bytes(key,48);
    printf("Key:%s\n",key);

    the outcome like this:
    Key:\360\330{\217\226\227.5\340!;\211b\302\353\233 \3640\304\346\337Z>\222\2257\227;\35560\225\262\25 0\334gyyX\340\377\277g#M\220\274\321

  4. #4
    - - - - - - - - oogabooga's Avatar
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    That's just a matter of how it's being displayed. Try this:
    Code:
    #define KEY_SIZE 48
    int i;
    unsigned char key[KEY_SIZE];
    RAND_bytes(key, KEY_SIZE);
    for (i = 0; i < KEY_SIZE; i++)
        printf("%02X ", key[i]);
    EDIT:
    If you actually need a string representation of the hex digits you can use sprintf:
    Code:
    #define KEY_SIZE 48
    int i;
    unsigned char key[KEY_SIZE];
    char keystr[KEY_SIZE * 2 + 1];
    RAND_bytes(key, KEY_SIZE);
    for (i = 0; i < KEY_SIZE; i++)
        sprintf(keystr + 2*i, "%02X", key[i]);
    printf("%s\n", keystr);
    Last edited by oogabooga; 04-06-2012 at 12:51 AM.
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

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    Oh!!!!! You are great!!! thx a lot!!!!

  6. #6
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    thx oogabooga, I want to ask 1 more question, Can I change this result to Charater pointer? (Char array (HEX) to Char * (HEX))

  7. #7
    Algorithm Dissector iMalc's Avatar
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    An array is implictly treated as a pointer to its first element when you pass it to the function. You don't need to do anything.
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