gpg: Initial support for generating Kyber subkeys.

* common/openpgpdefs.h (PUBKEY_ALGO_KY768_25519): Remove.
(PUBKEY_ALGO_KY1024_448): Remove.
(PUBKEY_ALGO_KYBER): New.  Use them everywhere instead of the removed.

* g10/build-packet.c (gpg_mpi_write_nohdr): Rename to
(gpg_mpi_write_opaque_nohdr): this.  Change callers.
(gpg_mpi_write_opaque_32): New.
(do_key): Support Kyber keys using the revised format.
* g10/gpg.h (MAX_EXTERN_KEYPARM_BITS): New.
* g10/parse-packet.c (read_octet_string): Add arg nbytes so support
reading with a length prefix.  Adjust callers.
(parse_key): Parse Kyber public keys.
* g10/misc.c (pubkey_get_npkey): Support Kyber.
(pubkey_get_nskey): Ditto.

* g10/keyid.c (pubkey_string): Support dual algorithms.
(do_hash_public_key): Support Kyber.
(nbits_from_pk): Ditto.
(keygrip_from_pk): Return the Kyber part for the ECC+Kyber dual algo.

* g10/keygen.c (struct common_gen_cb_parm_s): Add genkey_result2.
Note that this callback is not yet used.
(ecckey_from_sexp): Add optional arg sexp2 and use it for Kyber.
Change callers.
(ecckey_from_sexp): Do not leak LIST in case of an error.
(common_gen): Add arg keyparms2, change callers, and support Kyber.
(gen_kyber): New.
(get_keysize_range): Support Kyber.
(fixup_keysize): Simplify and support Kyber.
(do_create): Handle Kyber.
(parse_key_parameter_part): Remove algo strings "ky768" and "ky1024"
and add a generic "kyber" with default parameters.
--

This uses a revised format which is more aligned with the usual
OpenPGP structure.  A lot of things are still missing.  For example
support for handling two keygrips and checking both of them in a -K
listing.  There is also only ky768_bp384 as fixed algorithm for now.
No passphrase for the Kyber part of the dual algorithm is on purpose.

A test was done using

  gpg --quick-gen-key pqc1 nistp256

and then running

  gpg -v --quick-add-key <fingerprint> kyber

which creates a v5 subkey on a v4 primary key.  A second test using

  gpg --quick-gen-key pqc2 Ed448

followed by a --quick-add-key created a v5 key with a v5 subkey.

GnuPG-bug-id: 6815

1 files changed, 78 insertions, 17 deletions

diff --git a/g10/build-packet.c b/g10/build-packet.c
index 9927b7695..78828c8dc 100644
--- a/g10/build-packet.c
+++ b/g10/build-packet.c
@@ -433,7 +433,7 @@ sos_write (iobuf_t out, gcry_mpi_t a, unsigned int *r_nwritten)
  * Write an opaque string to the output stream without length info.
  */
 gpg_error_t
-gpg_mpi_write_nohdr (iobuf_t out, gcry_mpi_t a)
+gpg_mpi_write_opaque_nohdr (iobuf_t out, gcry_mpi_t a)
 {
   int rc;
 
@@ -452,6 +452,45 @@ gpg_mpi_write_nohdr (iobuf_t out, gcry_mpi_t a)
 }
 
 
+/*
+ * Write an opaque MPI string with a four-byte octet count to the
+ * output stream.  If R_NWRITTEN is not NULL the number of written
+ * bytes is stored there.  OUT may be NULL in which case only
+ * R_NWRITTEN is updated and error checking is done.
+ */
+gpg_error_t
+gpg_mpi_write_opaque_32 (iobuf_t out, gcry_mpi_t a, unsigned int *r_nwritten)
+{
+  gpg_error_t err;
+
+  if (gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
+    {
+      unsigned int nbits, nbytes;
+      const void *p;
+
+      p = gcry_mpi_get_opaque (a, &nbits);
+      nbytes = (nbits + 7)/8;
+      if (out)
+        {
+          write_32 (out, nbytes);
+          err = p ? iobuf_write (out, p, nbytes) : 0;
+        }
+      else
+        err = 0;
+      if (r_nwritten)
+        *r_nwritten = 4 + (p? nbytes : 0);
+    }
+  else
+    {
+      err = gpg_error (GPG_ERR_BAD_MPI);
+      if (r_nwritten)
+        *r_nwritten = 0;
+    }
+
+  return err;
+}
+
+
 /* Calculate the length of a packet described by PKT.  */
 u32
 calc_packet_length( PACKET *pkt )
@@ -639,8 +678,14 @@ do_key (iobuf_t out, int ctb, PKT_public_key *pk)
     {
       if (   (pk->pubkey_algo == PUBKEY_ALGO_ECDSA && (i == 0))
           || (pk->pubkey_algo == PUBKEY_ALGO_EDDSA && (i == 0))
-          || (pk->pubkey_algo == PUBKEY_ALGO_ECDH  && (i == 0 || i == 2)))
-        err = gpg_mpi_write_nohdr (a, pk->pkey[i]);
+          || (pk->pubkey_algo == PUBKEY_ALGO_ECDH  && (i == 0 || i == 2))
+          || (pk->pubkey_algo == PUBKEY_ALGO_KYBER && (i == 0)))
+        err = gpg_mpi_write_opaque_nohdr (a, pk->pkey[i]);
+      else if (pk->pubkey_algo == PUBKEY_ALGO_KYBER && i == 2)
+        {
+          /* Write a four-octet count prefixed Kyber public key.  */
+          err = gpg_mpi_write_opaque_32 (a, pk->pkey[2], NULL);
+        }
       else if (pk->pubkey_algo == PUBKEY_ALGO_ECDSA
                || pk->pubkey_algo == PUBKEY_ALGO_EDDSA
                || pk->pubkey_algo == PUBKEY_ALGO_ECDH)
@@ -779,9 +824,15 @@ do_key (iobuf_t out, int ctb, PKT_public_key *pk)
 
               for (j=i; j < nskey; j++ )
                 {
-                  if (pk->pubkey_algo == PUBKEY_ALGO_ECDSA
-                      || pk->pubkey_algo == PUBKEY_ALGO_EDDSA
-                      || pk->pubkey_algo == PUBKEY_ALGO_ECDH)
+                  if (pk->pubkey_algo == PUBKEY_ALGO_KYBER && j == 4)
+                    {
+                      if ((err=gpg_mpi_write_opaque_32 (NULL,pk->pkey[j], &n)))
+                        goto leave;
+                    }
+                  else if (pk->pubkey_algo == PUBKEY_ALGO_ECDSA
+                           || pk->pubkey_algo == PUBKEY_ALGO_EDDSA
+                           || pk->pubkey_algo == PUBKEY_ALGO_ECDH
+                           || pk->pubkey_algo == PUBKEY_ALGO_KYBER)
                     {
                       if ((err = sos_write (NULL, pk->pkey[j], &n)))
                         goto leave;
@@ -798,16 +849,26 @@ do_key (iobuf_t out, int ctb, PKT_public_key *pk)
             }
 
           for ( ; i < nskey; i++ )
-            if (pk->pubkey_algo == PUBKEY_ALGO_ECDSA
-                || pk->pubkey_algo == PUBKEY_ALGO_EDDSA
-                || pk->pubkey_algo == PUBKEY_ALGO_ECDH)
-              {
-                if ((err = sos_write (a, pk->pkey[i], NULL)))
-                  goto leave;
-              }
-            else
-              if ((err = gpg_mpi_write (a, pk->pkey[i], NULL)))
-                goto leave;
+            {
+              if (pk->pubkey_algo == PUBKEY_ALGO_KYBER && i == 4)
+                {
+                  err = gpg_mpi_write_opaque_32 (a, pk->pkey[i], NULL);
+                  if (err)
+                    goto leave;
+                }
+              else if (pk->pubkey_algo == PUBKEY_ALGO_ECDSA
+                       || pk->pubkey_algo == PUBKEY_ALGO_EDDSA
+                       || pk->pubkey_algo == PUBKEY_ALGO_ECDH)
+                {
+                  if ((err = sos_write (a, pk->pkey[i], NULL)))
+                    goto leave;
+                }
+              else
+                {
+                  if ((err = gpg_mpi_write (a, pk->pkey[i], NULL)))
+                    goto leave;
+                }
+            }
 
           write_16 (a, ski->csum );
         }
@@ -922,7 +983,7 @@ do_pubkey_enc( IOBUF out, int ctb, PKT_pubkey_enc *enc )
   for (i=0; i < n && !rc ; i++ )
     {
       if (enc->pubkey_algo == PUBKEY_ALGO_ECDH && i == 1)
-        rc = gpg_mpi_write_nohdr (a, enc->data[i]);
+        rc = gpg_mpi_write_opaque_nohdr (a, enc->data[i]);
       else if (enc->pubkey_algo == PUBKEY_ALGO_ECDH)
         rc = sos_write (a, enc->data[i], NULL);
       else