diff --git a/sm/certcheck.c b/sm/certcheck.c
index badad2fad..534f47c1b 100644
--- a/sm/certcheck.c
+++ b/sm/certcheck.c
@@ -1,624 +1,627 @@
 /* certcheck.c - check one certificate
  * Copyright (C) 2001, 2003, 2004 Free Software Foundation, Inc.
  * Copyright (C) 2001-2019 Werner Koch
  * Copyright (C) 2015-2020 g10 Code GmbH
  *
  * This file is part of GnuPG.
  *
  * GnuPG is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 3 of the License, or
  * (at your option) any later version.
  *
  * GnuPG is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, see <https://www.gnu.org/licenses/>.
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
 
 #include <config.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
 #include <unistd.h>
 #include <time.h>
 #include <assert.h>
 
 #include "gpgsm.h"
 #include <gcrypt.h>
 #include <ksba.h>
 
 #include "keydb.h"
 #include "../common/i18n.h"
 
 
 /* Return the number of bits of the Q parameter from the DSA key
    KEY.  */
 static unsigned int
 get_dsa_qbits (gcry_sexp_t key)
 {
   gcry_sexp_t l1, l2;
   gcry_mpi_t q;
   unsigned int nbits;
 
   l1 = gcry_sexp_find_token (key, "public-key", 0);
   if (!l1)
     return 0; /* Does not contain a key object.  */
   l2 = gcry_sexp_cadr (l1);
   gcry_sexp_release  (l1);
   l1 = gcry_sexp_find_token (l2, "q", 1);
   gcry_sexp_release (l2);
   if (!l1)
     return 0; /* Invalid object.  */
   q = gcry_sexp_nth_mpi (l1, 1, GCRYMPI_FMT_USG);
   gcry_sexp_release (l1);
   if (!q)
     return 0; /* Missing value.  */
   nbits = gcry_mpi_get_nbits (q);
   gcry_mpi_release (q);
 
   return nbits;
 }
 
 
 static int
 do_encode_md (gcry_md_hd_t md, int algo, int pkalgo, unsigned int nbits,
               gcry_sexp_t pkey, gcry_mpi_t *r_val)
 {
   int n;
   size_t nframe;
   unsigned char *frame;
 
   if (pkalgo == GCRY_PK_DSA || pkalgo == GCRY_PK_ECC)
     {
-      unsigned int qbits;
+      unsigned int qbits0, qbits;
 
       if ( pkalgo == GCRY_PK_ECC )
-        qbits = gcry_pk_get_nbits (pkey);
+        {
+          qbits0 = gcry_pk_get_nbits (pkey);
+          qbits = qbits0 == 521? 512 : qbits0;
+        }
       else
-        qbits = get_dsa_qbits (pkey);
+        qbits0 = qbits = get_dsa_qbits (pkey);
 
       if ( (qbits%8) )
 	{
 	  log_error(_("DSA requires the hash length to be a"
 		      " multiple of 8 bits\n"));
 	  return gpg_error (GPG_ERR_INTERNAL);
 	}
 
       /* Don't allow any Q smaller than 160 bits.  We don't want
 	 someone to issue signatures from a key with a 16-bit Q or
 	 something like that, which would look correct but allow
 	 trivial forgeries.  Yes, I know this rules out using MD5 with
 	 DSA. ;) */
       if (qbits < 160)
 	{
 	  log_error (_("%s key uses an unsafe (%u bit) hash\n"),
-                     gcry_pk_algo_name (pkalgo), qbits);
+                     gcry_pk_algo_name (pkalgo), qbits0);
 	  return gpg_error (GPG_ERR_INTERNAL);
 	}
 
       /* Check if we're too short.  Too long is safe as we'll
 	 automatically left-truncate. */
       nframe = gcry_md_get_algo_dlen (algo);
       if (nframe < qbits/8)
         {
 	  log_error (_("a %u bit hash is not valid for a %u bit %s key\n"),
                      (unsigned int)nframe*8,
-                     gcry_pk_get_nbits (pkey),
+                     qbits0,
                      gcry_pk_algo_name (pkalgo));
           /* FIXME: we need to check the requirements for ECDSA.  */
           if (nframe < 20 || pkalgo == GCRY_PK_DSA  )
             return gpg_error (GPG_ERR_INTERNAL);
         }
 
       frame = xtrymalloc (nframe);
       if (!frame)
         return out_of_core ();
       memcpy (frame, gcry_md_read (md, algo), nframe);
       n = nframe;
       /* Truncate.  */
       if (n > qbits/8)
         n = qbits/8;
     }
   else
     {
       int i;
       unsigned char asn[100];
       size_t asnlen;
       size_t len;
 
       nframe = (nbits+7) / 8;
 
       asnlen = DIM(asn);
       if (!algo || gcry_md_test_algo (algo))
         return gpg_error (GPG_ERR_DIGEST_ALGO);
       if (gcry_md_algo_info (algo, GCRYCTL_GET_ASNOID, asn, &asnlen))
         {
           log_error ("no object identifier for algo %d\n", algo);
           return gpg_error (GPG_ERR_INTERNAL);
         }
 
       len = gcry_md_get_algo_dlen (algo);
 
       if ( len + asnlen + 4  > nframe )
         {
           log_error ("can't encode a %d bit MD into a %d bits frame\n",
                      (int)(len*8), (int)nbits);
           return gpg_error (GPG_ERR_INTERNAL);
         }
 
       /* We encode the MD in this way:
        *
        *	   0  A PAD(n bytes)   0  ASN(asnlen bytes)  MD(len bytes)
        *
        * PAD consists of FF bytes.
        */
       frame = xtrymalloc (nframe);
       if (!frame)
         return out_of_core ();
       n = 0;
       frame[n++] = 0;
       frame[n++] = 1; /* block type */
       i = nframe - len - asnlen -3 ;
       assert ( i > 1 );
       memset ( frame+n, 0xff, i ); n += i;
       frame[n++] = 0;
       memcpy ( frame+n, asn, asnlen ); n += asnlen;
       memcpy ( frame+n, gcry_md_read(md, algo), len ); n += len;
       assert ( n == nframe );
     }
   if (DBG_CRYPTO)
     {
       int j;
       log_debug ("encoded hash:");
       for (j=0; j < nframe; j++)
         log_printf (" %02X", frame[j]);
       log_printf ("\n");
     }
 
   gcry_mpi_scan (r_val, GCRYMPI_FMT_USG, frame, n, &nframe);
   xfree (frame);
   return 0;
 }
 
 /* Return the public key algorithm id from the S-expression PKEY.
    FIXME: libgcrypt should provide such a function.  Note that this
    implementation uses the names as used by libksba.  */
 static int
 pk_algo_from_sexp (gcry_sexp_t pkey)
 {
   gcry_sexp_t l1, l2;
   const char *name;
   size_t n;
   int algo;
 
   l1 = gcry_sexp_find_token (pkey, "public-key", 0);
   if (!l1)
     return 0; /* Not found.  */
   l2 = gcry_sexp_cadr (l1);
   gcry_sexp_release (l1);
 
   name = gcry_sexp_nth_data (l2, 0, &n);
   if (!name)
     algo = 0; /* Not found. */
   else if (n==3 && !memcmp (name, "rsa", 3))
     algo = GCRY_PK_RSA;
   else if (n==3 && !memcmp (name, "dsa", 3))
     algo = GCRY_PK_DSA;
   else if (n==3 && !memcmp (name, "ecc", 3))
     algo = GCRY_PK_ECC;
   else if (n==13 && !memcmp (name, "ambiguous-rsa", 13))
     algo = GCRY_PK_RSA;
   else
     algo = 0;
   gcry_sexp_release (l2);
   return algo;
 }
 
 
 /* Return the hash algorithm's algo id from its name given in the
  * non-null termnated string in (buffer,buflen).  Returns 0 on failure
  * or if the algo is not known.  */
 static int
 hash_algo_from_buffer (const void *buffer, size_t buflen)
 {
   char *string;
   int algo;
 
   string = xtrymalloc (buflen + 1);
   if (!string)
     {
       log_error (_("out of core\n"));
       return 0;
     }
   memcpy (string, buffer, buflen);
   string[buflen] = 0;
   algo = gcry_md_map_name (string);
   if (!algo)
     log_error ("unknown digest algorithm '%s' used in certificate\n", string);
   xfree (string);
   return algo;
 }
 
 
 /* Return an unsigned integer from the non-null termnated string
  * (buffer,buflen).  Returns 0 on failure.  */
 static unsigned int
 uint_from_buffer (const void *buffer, size_t buflen)
 {
   char *string;
   unsigned int val;
 
   string = xtrymalloc (buflen + 1);
   if (!string)
     {
       log_error (_("out of core\n"));
       return 0;
     }
   memcpy (string, buffer, buflen);
   string[buflen] = 0;
   val = strtoul (string, NULL, 10);
   xfree (string);
   return val;
 }
 
 
 /* Extract the hash algorithm and the salt length from the sigval.  */
 static gpg_error_t
 extract_pss_params (gcry_sexp_t s_sig, int *r_algo, unsigned int *r_saltlen)
 {
   gpg_error_t err;
   gcry_buffer_t ioarray[2] = { {0}, {0} };
 
   err = gcry_sexp_extract_param (s_sig, "sig-val",
                                  "&'hash-algo''salt-length'",
                                  ioarray+0, ioarray+1, NULL);
   if (err)
     {
       log_error ("extracting params from PSS failed: %s\n", gpg_strerror (err));
       return err;
     }
 
   *r_algo = hash_algo_from_buffer (ioarray[0].data, ioarray[0].len);
   *r_saltlen = uint_from_buffer (ioarray[1].data, ioarray[1].len);
   xfree (ioarray[0].data);
   xfree (ioarray[1].data);
   if (*r_saltlen < 20)
     {
       log_error ("length of PSS salt too short\n");
       return gpg_error (GPG_ERR_DIGEST_ALGO);
     }
   if (!*r_algo)
     {
       return gpg_error (GPG_ERR_DIGEST_ALGO);
     }
 
   /* PSS has no hash function firewall like PKCS#1 and thus offers
    * a path for hash algorithm replacement.  To avoid this it makes
    * sense to restrict the allowed hash algorithms and also allow only
    * matching salt lengths.  According to Peter Gutmann:
    *  "Beware of bugs in the above signature scheme;
    *   I have only proved it secure, not implemented it"
    *   - Apologies to Donald Knuth.
    * https://www.metzdowd.com/pipermail/cryptography/2019-November/035449.html
    *
    * Given the set of supported algorithms currently available in
    * Libgcrypt and the extra hash checks we have in some compliance
    * modes, it would be hard to trick gpgsm to verify a forged
    * signature.  However, if eventually someone adds the xor256 hash
    * algorithm (1.3.6.1.4.1.3029.3.2) to Libgcrypt we would be doomed.
    */
   switch (*r_algo)
     {
     case GCRY_MD_SHA1:
     case GCRY_MD_SHA256:
     case GCRY_MD_SHA384:
     case GCRY_MD_SHA512:
     case GCRY_MD_SHA3_256:
     case GCRY_MD_SHA3_384:
     case GCRY_MD_SHA3_512:
       break;
     default:
       log_error ("PSS hash algorithm '%s' rejected\n",
                  gcry_md_algo_name (*r_algo));
       return gpg_error (GPG_ERR_DIGEST_ALGO);
     }
 
   if (gcry_md_get_algo_dlen (*r_algo) != *r_saltlen)
     {
       log_error ("PSS hash algorithm '%s' rejected due to salt length %u\n",
                  gcry_md_algo_name (*r_algo), *r_saltlen);
       return gpg_error (GPG_ERR_DIGEST_ALGO);
     }
 
   return 0;
 }
 
 
 /* Check the signature on CERT using the ISSUER-CERT.  This function
    does only test the cryptographic signature and nothing else.  It is
    assumed that the ISSUER_CERT is valid. */
 int
 gpgsm_check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
 {
   const char *algoid;
   gcry_md_hd_t md;
   int rc, algo;
   ksba_sexp_t p;
   size_t n;
   gcry_sexp_t s_sig, s_data, s_pkey;
   int use_pss = 0;
   unsigned int saltlen;
 
   /* Note that we map the 4 algos which current Libgcrypt versions are
    * not aware of the OID.  */
   algo = gcry_md_map_name ( (algoid=ksba_cert_get_digest_algo (cert)));
   if (!algo && algoid && !strcmp (algoid, "1.2.840.113549.1.1.10"))
     use_pss = 1;
   else if (!algo && algoid && !strcmp (algoid, "1.2.840.10045.4.3.1"))
     algo = GCRY_MD_SHA224; /* ecdsa-with-sha224 */
   else if (!algo && algoid && !strcmp (algoid, "1.2.840.10045.4.3.2"))
     algo = GCRY_MD_SHA256; /* ecdsa-with-sha256 */
   else if (!algo && algoid && !strcmp (algoid, "1.2.840.10045.4.3.3"))
     algo = GCRY_MD_SHA384; /* ecdsa-with-sha384 */
   else if (!algo && algoid && !strcmp (algoid, "1.2.840.10045.4.3.4"))
     algo = GCRY_MD_SHA512; /* ecdsa-with-sha512 */
   else if (!algo)
     {
       log_error ("unknown digest algorithm '%s' used certificate\n",
                  algoid? algoid:"?");
       if (algoid
           && (  !strcmp (algoid, "1.2.840.113549.1.1.2")
                 ||!strcmp (algoid, "1.2.840.113549.2.2")))
         log_info (_("(this is the MD2 algorithm)\n"));
       return gpg_error (GPG_ERR_GENERAL);
     }
 
   /* The the signature from the certificate.  */
   p = ksba_cert_get_sig_val (cert);
   n = gcry_sexp_canon_len (p, 0, NULL, NULL);
   if (!n)
     {
       log_error ("libksba did not return a proper S-Exp\n");
       ksba_free (p);
       return gpg_error (GPG_ERR_BUG);
     }
   rc = gcry_sexp_sscan ( &s_sig, NULL, (char*)p, n);
   ksba_free (p);
   if (rc)
     {
       log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
       return rc;
     }
   if (DBG_CRYPTO)
     gcry_log_debugsxp ("sigval", s_sig);
 
   if (use_pss)
     {
       rc = extract_pss_params (s_sig, &algo, &saltlen);
       if (rc)
         {
           gcry_sexp_release (s_sig);
           return rc;
         }
     }
 
 
   /* Hash the to-be-signed parts of the certificate.  */
   rc = gcry_md_open (&md, algo, 0);
   if (rc)
     {
       log_error ("md_open failed: %s\n", gpg_strerror (rc));
       return rc;
     }
   if (DBG_HASHING)
     gcry_md_debug (md, "hash.cert");
 
   rc = ksba_cert_hash (cert, 1, HASH_FNC, md);
   if (rc)
     {
       log_error ("ksba_cert_hash failed: %s\n", gpg_strerror (rc));
       gcry_md_close (md);
       return rc;
     }
   gcry_md_final (md);
 
   /* Get the public key from the certificate.  */
   p = ksba_cert_get_public_key (issuer_cert);
   n = gcry_sexp_canon_len (p, 0, NULL, NULL);
   if (!n)
     {
       log_error ("libksba did not return a proper S-Exp\n");
       gcry_md_close (md);
       ksba_free (p);
       gcry_sexp_release (s_sig);
       return gpg_error (GPG_ERR_BUG);
     }
   rc = gcry_sexp_sscan ( &s_pkey, NULL, (char*)p, n);
   ksba_free (p);
   if (rc)
     {
       log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
       gcry_md_close (md);
       gcry_sexp_release (s_sig);
       return rc;
     }
   if (DBG_CRYPTO)
     gcry_log_debugsxp ("pubkey:", s_pkey);
 
   if (use_pss)
     {
       rc = gcry_sexp_build (&s_data, NULL,
                             "(data (flags pss)"
                             "(hash %s %b)"
                             "(salt-length %u))",
                             hash_algo_to_string (algo),
                             (int)gcry_md_get_algo_dlen (algo),
                             gcry_md_read (md, algo),
                             saltlen);
       if (rc)
         BUG ();
     }
   else
     {
       /* RSA or DSA: Prepare the hash for verification.  */
       gcry_mpi_t frame;
 
       rc = do_encode_md (md, algo, pk_algo_from_sexp (s_pkey),
                          gcry_pk_get_nbits (s_pkey), s_pkey, &frame);
       if (rc)
         {
           gcry_md_close (md);
           gcry_sexp_release (s_sig);
           gcry_sexp_release (s_pkey);
           return rc;
         }
       if ( gcry_sexp_build (&s_data, NULL, "%m", frame) )
         BUG ();
       gcry_mpi_release (frame);
     }
   if (DBG_CRYPTO)
     gcry_log_debugsxp ("data:", s_data);
 
   /* Verify.  */
   rc = gcry_pk_verify (s_sig, s_data, s_pkey);
   if (DBG_X509)
       log_debug ("gcry_pk_verify: %s\n", gpg_strerror (rc));
   gcry_md_close (md);
   gcry_sexp_release (s_sig);
   gcry_sexp_release (s_data);
   gcry_sexp_release (s_pkey);
   return rc;
 }
 
 
 
 int
 gpgsm_check_cms_signature (ksba_cert_t cert, gcry_sexp_t s_sig,
                            gcry_md_hd_t md, int mdalgo,
                            unsigned int pkalgoflags, int *r_pkalgo)
 {
   int rc;
   ksba_sexp_t p;
   gcry_sexp_t s_hash, s_pkey;
   size_t n;
   int pkalgo;
   int use_pss;
   unsigned int saltlen = 0;
 
   if (r_pkalgo)
     *r_pkalgo = 0;
 
   /* Check whether rsaPSS is needed.  This information is indicated in
    * the SIG-VAL and already provided to us by the caller so that we
    * do not need to parse this out. */
   use_pss = !!(pkalgoflags & PK_ALGO_FLAG_RSAPSS);
   if (use_pss)
     {
       int algo;
 
       rc = extract_pss_params (s_sig, &algo, &saltlen);
       if (rc)
         {
           gcry_sexp_release (s_sig);
           return rc;
         }
       if (algo != mdalgo)
         {
           log_error ("PSS hash algo mismatch (%d/%d)\n", mdalgo, algo);
           gcry_sexp_release (s_sig);
           return gpg_error (GPG_ERR_DIGEST_ALGO);
         }
     }
 
   p = ksba_cert_get_public_key (cert);
   n = gcry_sexp_canon_len (p, 0, NULL, NULL);
   if (!n)
     {
       log_error ("libksba did not return a proper S-Exp\n");
       ksba_free (p);
       return gpg_error (GPG_ERR_BUG);
     }
   if (DBG_CRYPTO)
     log_printhex (p, n, "public key: ");
 
   rc = gcry_sexp_sscan ( &s_pkey, NULL, (char*)p, n);
   ksba_free (p);
   if (rc)
     {
       log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
       return rc;
     }
 
   pkalgo = pk_algo_from_sexp (s_pkey);
   if (r_pkalgo)
     *r_pkalgo = pkalgo;
 
   if (use_pss)
     {
       rc = gcry_sexp_build (&s_hash, NULL,
                             "(data (flags pss)"
                             "(hash %s %b)"
                             "(salt-length %u))",
                             hash_algo_to_string (mdalgo),
                             (int)gcry_md_get_algo_dlen (mdalgo),
                             gcry_md_read (md, mdalgo),
                             saltlen);
       if (rc)
         BUG ();
     }
   else
     {
       /* RSA or DSA: Prepare the hash for verification.  */
       gcry_mpi_t frame;
 
       rc = do_encode_md (md, mdalgo, pkalgo,
                          gcry_pk_get_nbits (s_pkey), s_pkey, &frame);
       if (rc)
         {
           gcry_sexp_release (s_pkey);
           return rc;
         }
       /* put hash into the S-Exp s_hash */
       if ( gcry_sexp_build (&s_hash, NULL, "%m", frame) )
         BUG ();
       gcry_mpi_release (frame);
     }
 
   rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
   if (DBG_X509)
     log_debug ("gcry_pk_verify: %s\n", gpg_strerror (rc));
   gcry_sexp_release (s_hash);
   gcry_sexp_release (s_pkey);
   return rc;
 }
 
 
 
 int
 gpgsm_create_cms_signature (ctrl_t ctrl, ksba_cert_t cert,
                             gcry_md_hd_t md, int mdalgo,
                             unsigned char **r_sigval)
 {
   int rc;
   char *grip, *desc;
   size_t siglen;
 
   grip = gpgsm_get_keygrip_hexstring (cert);
   if (!grip)
     return gpg_error (GPG_ERR_BAD_CERT);
 
   desc = gpgsm_format_keydesc (cert);
 
   rc = gpgsm_agent_pksign (ctrl, grip, desc, gcry_md_read(md, mdalgo),
                            gcry_md_get_algo_dlen (mdalgo), mdalgo,
                            r_sigval, &siglen);
   xfree (desc);
   xfree (grip);
   return rc;
 }