e902893a-9d22-3c7e-a7b8-d6e313b71d9f
RFC4122 Erroneous MD5-based example

RFC4122 Erroneous MD5-based example

The given value e902... etc. is based on a calculation swapping the eight octets 0..3, 4..5, 6..7 twice, for the name space UUID, and for the MD5 output, as foreseen for little endian input, but the example values were already big endian. I can reproduce the example and the proposed fix, see <http://omniplex.blogspot.com/2008/03/md5-16-pop3-and-uuid.html>.

The blog entry contains links to an identical older error report, and two (different) examples from third parties also agreeing with that theory.

https://www.rfc-editor.org/errata/rfc4122https://www.rfc-editor.org/errata/rfc4122
0 Frank Ellermann, probably
Seen in rfc4122

Seen in RFC 4122
Counts : rfc4122:1
RFC 4122                  A UUID URN Namespace                 July 2005


uuid_t NameSpace_DNS = { /* 6ba7b810-9dad-11d1-80b4-00c04fd430c8 */
    0x6ba7b810,
    0x9dad,
    0x11d1,
    0x80, 0xb4, 0x00, 0xc0, 0x4f, 0xd4, 0x30, 0xc8
};

/* puid -- print a UUID */
void puid(uuid_t u)
{
    int i;

    printf("%8.8x-%4.4x-%4.4x-%2.2x%2.2x-", u.time_low, u.time_mid,
    u.time_hi_and_version, u.clock_seq_hi_and_reserved,
    u.clock_seq_low);
    for (i = 0; i < 6; i++)
        printf("%2.2x", u.node[i]);
    printf("\n");
}

/* Simple driver for UUID generator */
void main(int argc, char **argv)
{
    uuid_t u;
    int f;

    uuid_create(&u);
    printf("uuid_create(): "); puid(u);

    f = uuid_compare(&u, &u);
    printf("uuid_compare(u,u): %d\n", f);     /* should be 0 */
    f = uuid_compare(&u, &NameSpace_DNS);
    printf("uuid_compare(u, NameSpace_DNS): %d\n", f); /* s.b. 1 */
    f = uuid_compare(&NameSpace_DNS, &u);
    printf("uuid_compare(NameSpace_DNS, u): %d\n", f); /* s.b. -1 */
    uuid_create_md5_from_name(&u, NameSpace_DNS, "www.widgets.com", 15);
    printf("uuid_create_md5_from_name(): "); puid(u);
}

Appendix B.  Appendix B - Sample Output of utest

     uuid_create(): 7d444840-9dc0-11d1-b245-5ffdce74fad2
     uuid_compare(u,u): 0
     uuid_compare(u, NameSpace_DNS): 1
     uuid_compare(NameSpace_DNS, u): -1
     uuid_create_md5_from_name(): e902893a-9d22-3c7e-a7b8-d6e313b71d9f





Leach, et al.               Standards Track                    [Page 29]
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