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Code Activity

dirmngr: Support ECDSA for CRLs

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* dirmngr/crlcache.c (finish_sig_check): Support ECDSA.
* dirmngr/validate.c (check_cert_sig): Ditto.  Remove the never
used support for DSA.
This commit is contained in:
Werner Koch 2022-02-27 12:13:49 +01:00
parent 890e9849b5
commit de87c8e1ea
No known key found for this signature in database
GPG Key ID: E3FDFF218E45B72B
2 changed files with 92 additions and 12 deletions
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48
dirmngr/crlcache.c
View File

@ -1660,6 +1660,7 @@ finish_sig_check (ksba_crl_t crl, gcry_md_hd_t md, int algo,
size_t n;
gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL;
unsigned int saltlen = 0; /* (used only with use_pss) */
int pkalgo;
/* This also stops debugging on the MD. */
gcry_md_final (md);
@ -1787,6 +1788,53 @@ finish_sig_check (ksba_crl_t crl, gcry_md_hd_t md, int algo,
gcry_md_read (md, algo),
saltlen);
}
else if ((pkalgo = pk_algo_from_sexp (s_pkey)) == GCRY_PK_ECC)
{
unsigned int qbits0, qbits;
qbits0 = gcry_pk_get_nbits (s_pkey);
qbits = qbits0 == 521? 512 : qbits0;
if ((qbits%8))
{
log_error ("ECDSA requires the hash length to be a"
" multiple of 8 bits\n");
err = gpg_error (GPG_ERR_INTERNAL);
goto leave;
}
/* Don't allow any Q smaller than 160 bits. */
if (qbits < 160)
{
log_error (_("%s key uses an unsafe (%u bit) hash\n"),
gcry_pk_algo_name (pkalgo), qbits0);
err = gpg_error (GPG_ERR_INTERNAL);
goto leave;
}
/* Check if we're too short. */
n = gcry_md_get_algo_dlen (algo);
if (n < qbits/8)
{
log_error (_("a %u bit hash is not valid for a %u bit %s key\n"),
(unsigned int)n*8,
qbits0,
gcry_pk_algo_name (pkalgo));
if (n < 20)
{
err = gpg_error (GPG_ERR_INTERNAL);
goto leave;
}
}
/* Truncate. */
if (n > qbits/8)
n = qbits/8;
err = gcry_sexp_build (&s_hash, NULL, "%b",
(int)n,
gcry_md_read (md, algo));
}
else
{
err = gcry_sexp_build (&s_hash, NULL,

56
dirmngr/validate.c
View File

@ -231,7 +231,8 @@ allowed_ca (ksba_cert_t cert, int *chainlen)
/* The German SigG Root CA's certificate does not flag
itself as a CA; thus we relax this requirement if we
trust a root CA. I think this is reasonable. Note, that
gpgsm implements a far stricter scheme here. */
gpgsm implements a far stricter scheme here but also
features a "relax" flag in the trustlist.txt. */
if (chainlen)
*chainlen = 3; /* That is what the SigG implements. */
if (opt.verbose)
@ -954,7 +955,7 @@ check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
int digestlen;
unsigned char *digest;
int use_pss = 0;
unsigned int saltlen;
unsigned int saltlen; /* (use is controlled by use_pss) */
/* Hash the target certificate using the algorithm from that certificate. */
algoid = ksba_cert_get_digest_algo (cert);
@ -1108,19 +1109,48 @@ check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
digest,
saltlen);
}
else if (pk_algo_from_sexp (s_pkey) == GCRY_PK_DSA)
else if (pk_algo_from_sexp (s_pkey) == GCRY_PK_ECC)
{
/* NB.: We support only SHA-1 here because we had problems back
* then to get test data for DSA-2. Meanwhile DSA has been
* replaced by ECDSA which we do not yet support. */
if (digestlen != 20)
unsigned int qbits0, qbits;
qbits0 = gcry_pk_get_nbits (s_pkey);
qbits = qbits0 == 521? 512 : qbits0;
if ((qbits%8))
{
log_error ("DSA requires the use of a 160 bit hash algorithm\n");
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_pkey);
return gpg_error (GPG_ERR_INTERNAL);
log_error ("ECDSA requires the hash length to be a"
" multiple of 8 bits\n");
err = gpg_error (GPG_ERR_INTERNAL);
goto leave;
}
/* Don't allow any Q smaller than 160 bits. */
if (qbits < 160)
{
log_error (_("%s key uses an unsafe (%u bit) hash\n"),
"ECDSA", qbits0);
err = gpg_error (GPG_ERR_INTERNAL);
goto leave;
}
/* Check if we're too short. */
if (digestlen < qbits/8)
{
log_error (_("a %u bit hash is not valid for a %u bit %s key\n"),
(unsigned int)digestlen*8,
qbits0,
"ECDSA");
if (digestlen < 20)
{
err = gpg_error (GPG_ERR_INTERNAL);
goto leave;
}
}
/* Truncate. */
if (digestlen > qbits/8)
digestlen = qbits/8;
err = gcry_sexp_build (&s_hash, NULL, "(data(flags raw)(value %b))",
(int)digestlen, digest);
}
@ -1134,6 +1164,8 @@ check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
err = gcry_pk_verify (s_sig, s_hash, s_pkey);
if (DBG_X509)
log_debug ("gcry_pk_verify: %s\n", gpg_strerror (err));
leave:
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);