gpg,ecc: Handle external representation as SOS with opaque MPI.

* g10/pkglue.h (sexp_extract_param_sos): New.
* g10/build-packet.c (sos_write): New.
(do_key, do_pubkey_enc, do_signature): Use sos_write for ECC.
* g10/export.c (cleartext_secret_key_to_openpgp): Use
sexp_extract_param_sos.
(transfer_format_to_openpgp): Use opaque MPI for ECC.
* g10/keygen.c (ecckey_from_sexp): Use sexp_extract_param_sos.
* g10/keyid.c (hash_public_key): Handle opaque MPI for SOS.
* g10/parse-packet.c (sos_read): New.
(parse_pubkeyenc,parse_signature,parse_key): Use sos_read for ECC.
* g10/pkglue.c (sexp_extract_param_sos): New.
(pk_verify): Handle opaque MPI for SOS.
(pk_encrypt): Use sexp_extract_param_sos.
* g10/seskey.c (encode_session_key): Use opaque MPI.
* g10/sign.c (do_sign): Use sexp_extract_param_sos.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

1 files changed, 100 insertions, 7 deletions

diff --git a/g10/build-packet.c b/g10/build-packet.c
index a1db0251d..268bd71b2 100644
--- a/g10/build-packet.c
+++ b/g10/build-packet.c
@@ -364,7 +364,71 @@ gpg_mpi_write (iobuf_t out, gcry_mpi_t a, unsigned int *r_nwritten)
 
 
 /*
- * Write an opaque MPI to the output stream without length info.
+ * Write the mpi A to the output stream OUT as "SOS" (Strange Octet
+ * String).  If R_NWRITTEN is not NULL the number of bytes written is
+ * stored there.  To only get the number of bytes which would be
+ * written, NULL may be passed for OUT.
+ */
+static gpg_error_t
+sos_write (iobuf_t out, gcry_mpi_t a, unsigned int *r_nwritten)
+{
+  gpg_error_t err;
+  unsigned int nwritten = 0;
+
+  if (gcry_mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
+    {
+      unsigned int nbits;
+      const unsigned char *p;
+      unsigned char lenhdr[2];
+
+      /* gcry_log_debugmpi ("a", a); */
+      p = gcry_mpi_get_opaque (a, &nbits);
+      /* gcry_log_debug ("   [%u bit]\n", nbits); */
+      /* gcry_log_debughex (" ", p, (nbits+7)/8); */
+
+      if (p && *p)
+        {
+          nbits = ((nbits + 7) / 8) * 8;
+
+          if (nbits >= 8 && !(*p & 0x80))
+            if (--nbits >= 7 && !(*p & 0x40))
+              if (--nbits >= 6 && !(*p & 0x20))
+                if (--nbits >= 5 && !(*p & 0x10))
+                  if (--nbits >= 4 && !(*p & 0x08))
+                    if (--nbits >= 3 && !(*p & 0x04))
+                      if (--nbits >= 2 && !(*p & 0x02))
+                        if (--nbits >= 1 && !(*p & 0x01))
+                          --nbits;
+        }
+
+      lenhdr[0] = nbits >> 8;
+      lenhdr[1] = nbits;
+      err = out? iobuf_write (out, lenhdr, 2) : 0;
+      if (!err)
+        {
+          nwritten += 2;
+          if (p)
+            {
+              err = out? iobuf_write (out, p, (nbits+7)/8) : 0;
+              if (!err)
+                nwritten += (nbits+7)/8;
+            }
+        }
+    }
+  else
+    {
+      log_info ("non-opaque MPI (%u bits) for SOS\n", gcry_mpi_get_nbits (a));
+      err = gpg_error (GPG_ERR_INV_DATA);
+    }
+
+  if (r_nwritten)
+    *r_nwritten = nwritten;
+  return err;
+}
+
+
+/*
+ * 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)
@@ -575,6 +639,10 @@ do_key (iobuf_t out, int ctb, PKT_public_key *pk)
           || (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]);
+      else if (pk->pubkey_algo == PUBKEY_ALGO_ECDSA
+               || pk->pubkey_algo == PUBKEY_ALGO_EDDSA
+               || pk->pubkey_algo == PUBKEY_ALGO_ECDH)
+        err = sos_write (a, pk->pkey[i], NULL);
       else
         err = gpg_mpi_write (a, pk->pkey[i], NULL);
       if (err)
@@ -691,8 +759,18 @@ do_key (iobuf_t out, int ctb, PKT_public_key *pk)
 
               for (j=i; j < nskey; j++ )
                 {
-                  if ((err = gpg_mpi_write (NULL, pk->pkey[j], &n)))
-                    goto leave;
+                  if (pk->pubkey_algo == PUBKEY_ALGO_ECDSA
+                      || pk->pubkey_algo == PUBKEY_ALGO_EDDSA
+                      || pk->pubkey_algo == PUBKEY_ALGO_ECDH)
+                    {
+                      if ((err = sos_write (NULL, pk->pkey[j], &n)))
+                        goto leave;
+                    }
+                  else
+                    {
+                      if ( (err = gpg_mpi_write (a, pk->pkey[i], NULL)))
+                        goto leave;
+                    }
                   skbytes += n;
                 }
 
@@ -700,8 +778,16 @@ do_key (iobuf_t out, int ctb, PKT_public_key *pk)
             }
 
           for ( ; i < nskey; i++ )
-            if ( (err = gpg_mpi_write (a, pk->pkey[i], NULL)))
-              goto leave;
+            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 );
         }
@@ -817,6 +903,8 @@ do_pubkey_enc( IOBUF out, int ctb, PKT_pubkey_enc *enc )
     {
       if (enc->pubkey_algo == PUBKEY_ALGO_ECDH && i == 1)
         rc = gpg_mpi_write_nohdr (a, enc->data[i]);
+      else if (enc->pubkey_algo == PUBKEY_ALGO_ECDH)
+        rc = sos_write (a, enc->data[i], NULL);
       else
         rc = gpg_mpi_write (a, enc->data[i], NULL);
     }
@@ -1696,8 +1784,13 @@ do_signature( IOBUF out, int ctb, PKT_signature *sig )
   n = pubkey_get_nsig( sig->pubkey_algo );
   if ( !n )
     write_fake_data( a, sig->data[0] );
-  for (i=0; i < n && !rc ; i++ )
-    rc = gpg_mpi_write (a, sig->data[i], NULL);
+  if (sig->pubkey_algo == PUBKEY_ALGO_ECDSA
+      || sig->pubkey_algo == PUBKEY_ALGO_EDDSA)
+    for (i=0; i < n && !rc ; i++ )
+      rc = sos_write (a, sig->data[i], NULL);
+  else
+    for (i=0; i < n && !rc ; i++ )
+      rc = gpg_mpi_write (a, sig->data[i], NULL);
 
   if (!rc)
     {