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Re: Hard time to verify ssl server certificate.

From: Josef Wolf <jw_at_raven.inka.de>
Date: 2005-03-02 23:31:45 CET

On Mon, Feb 28, 2005 at 06:47:18PM +0100, Tobias Ringström wrote:
> Josef Wolf wrote:
> >Do you know a better way? tinyca gave me the md5, probably because this
> >is the default with RSA keys. svn presented sha1. How do I verify that
> >the certificate is valid when I have only md5 and svn presents me sha1?
> [I agree with everything Sussman has said, and I can confirm that neon
> is only giving us the SHA-1 fingerprint, although it does not seem to be
> documented anywhere.]
> There are two problems here. The first is that Subversion does not
> specify that it's displaying the SHA-1 fingerprint (although you tell in
> a hackish way by the different fingerprint size), and the second is that
> tinyca (which I know nothing about, btw) does not show you the SHA-1
> fingerprint. I will work on making Subversion say that it's showing the
> SHA-1 fingerprint, but you might want to contact the author of tinyca to
> also show the SHA-1 fingerprint as well as the MD5 fingerprint.

Judging from the openssl documentation:

       the digest to use. This affects any signing or display option
       that uses a message digest, such as the -fingerprint, -signkey
       and -CA options. If not specified then MD5 is used. If the key
       being used to sign with is a DSA key then this option has no
       effect: SHA1 is always used with DSA keys.

it looks to me that md5 is the default not only for tinyca, but for openssl
too. Therefore it looks to me as if tinyca is doing the right thing. Thus,
IMHO, svn should print the sha1 digest only on DSA keys. Since svn doesn't
have options to select _which_ digest to print, both (md5 and sha1) should
be printed.

BTW: From http://svn.webdav.org/repos/projects/neon/trunk/src/ne_openssl.c:

  int ne_ssl_cert_digest(const ne_ssl_certificate *cert, char *digest)
      unsigned char sha1[EVP_MAX_MD_SIZE];
      unsigned int len, j;
      char *p;

      if (!X509_digest(cert->subject, EVP_sha1(), sha1, &len) || len != 20) {
          return -1;

      for (j = 0, p = digest; j < 20; j++) {
          *p++ = NE_HEX2ASC((sha1[j] >> 4) & 0x0f);
          *p++ = NE_HEX2ASC(sha1[j] & 0x0f);
          *p++ = ':';

      p[-1] = '\0';
      return 0;

This looks to me as if md5 is not implemented at all in neon?

> In the mean time, you should be able to generate an SHA-1 fingerprint
> when you create the certificate using openssl using something like
> openssl x509 -in server.crt -noout -fingerprint -sha1

As I wrote earlier, this command don't work because svn stores the
certificate in a format that is not recognized by the openssl command. :(

No software patents!
-- Josef Wolf -- jw@raven.inka.de --
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Received on Wed Mar 2 23:42:33 2005

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