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common: Correctly render SHA256-based ssh fingerprints.

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* common/ssh-utils.c (dummy_realloc): New function.
(dummy_free): Likewise.
(get_fingerprint): Prepend the fingerprint with the name of the digest
algorithm.  Correctly render SHA256-based ssh fingerprints.
* common/t-ssh-utils.c (sample_keys): Add SHA256 hashes for the keys.
(main): Add an option to dump the keys to gather fingerprints, also
print the SHA256 fingerprint for keys given as arguments, and check
the SHA256 fingerprints of the test keys.

GnuPG-bug-id: 2106
Signed-off-by: Justus Winter <justus@g10code.com>
This commit is contained in:
Justus Winter 2017-05-24 17:03:58 +02:00
parent 3ac1a9d3a0
commit 3a07a69dfc
No known key found for this signature in database
GPG key ID: DD1A52F9DA8C9020
2 changed files with 158 additions and 14 deletions
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73
common/ssh-utils.c
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@ -64,6 +64,9 @@ is_eddsa (gcry_sexp_t keyparms)
return result;
}
/* Dummy functions for es_mopen. */
static void *dummy_realloc (void *mem, size_t size) { (void) size; return mem; }
static void dummy_free (void *mem) { (void) mem; }
/* Return the Secure Shell type fingerprint for KEY using digest ALGO.
The length of the fingerprint is returned at R_LEN and the
@ -232,10 +235,74 @@ get_fingerprint (gcry_sexp_t key, int algo,
if (as_string)
{
*r_fpr = (algo == GCRY_MD_MD5 ? bin2hexcolon : /* XXX we need base64 */ bin2hex)
(gcry_md_read (md, algo), gcry_md_get_algo_dlen (algo), NULL);
const char *algo_name;
char *fpr;
/* Prefix string with the algorithm name and a colon. */
algo_name = gcry_md_algo_name (algo);
*r_fpr = xtrymalloc (strlen (algo_name) + 1 + 3 * gcry_md_get_algo_dlen (algo) + 1);
if (*r_fpr == NULL)
{
err = gpg_err_make (default_errsource, gpg_err_code_from_syserror ());
goto leave;
}
strncpy (*r_fpr, algo_name, strlen (algo_name));
fpr = (char *) *r_fpr + strlen (algo_name);
*fpr++ = ':';
if (algo == GCRY_MD_MD5)
{
bin2hexcolon (gcry_md_read (md, algo), gcry_md_get_algo_dlen (algo), fpr);
strlwr (fpr);
}
else
{
struct b64state b64s;
estream_t stream;
char *p;
long int len;
/* Write the base64-encoded hash to fpr. */
stream = es_mopen (fpr, 3 * gcry_md_get_algo_dlen (algo) + 1, 0,
0, dummy_realloc, dummy_free, "w");
if (stream == NULL)
{
err = gpg_err_make (default_errsource, gpg_err_code_from_syserror ());
goto leave;
}
err = b64enc_start_es (&b64s, stream, "");
if (err)
{
es_fclose (stream);
goto leave;
}
err = b64enc_write (&b64s,
gcry_md_read (md, algo), gcry_md_get_algo_dlen (algo));
if (err)
{
es_fclose (stream);
goto leave;
}
/* Finish, get the length, and close the stream. */
err = b64enc_finish (&b64s);
len = es_ftell (stream);
es_fclose (stream);
if (err)
goto leave;
/* Terminate. */
fpr[len] = 0;
/* Strip the trailing padding characters. */
for (p = fpr + len - 1; p > fpr && *p == '='; p--)
*p = 0;
}
*r_len = strlen (*r_fpr) + 1;
strlwr (*r_fpr);
}
else
{