added MirOTR

git-svn-id: http://svn.miranda-ng.org/main/trunk@83 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c

1 files changed, 1182 insertions, 0 deletions

diff --git a/plugins/MirOTR/libgcrypt-1.4.6/cipher/dsa.c b/plugins/MirOTR/libgcrypt-1.4.6/cipher/dsa.c
new file mode 100644
index 0000000000..ceb94965c5
--- /dev/null
+++ b/plugins/MirOTR/libgcrypt-1.4.6/cipher/dsa.c
@@ -0,0 +1,1182 @@
+/* dsa.c - DSA signature algorithm
+ * Copyright (C) 1998, 2000, 2001, 2002, 2003,
+ *               2006, 2008  Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "g10lib.h"
+#include "mpi.h"
+#include "cipher.h"
+
+typedef struct
+{
+  gcry_mpi_t p;	    /* prime */
+  gcry_mpi_t q;	    /* group order */
+  gcry_mpi_t g;	    /* group generator */
+  gcry_mpi_t y;	    /* g^x mod p */
+} DSA_public_key;
+
+
+typedef struct
+{
+  gcry_mpi_t p;	    /* prime */
+  gcry_mpi_t q;	    /* group order */
+  gcry_mpi_t g;	    /* group generator */
+  gcry_mpi_t y;	    /* g^x mod p */
+  gcry_mpi_t x;	    /* secret exponent */
+} DSA_secret_key;
+
+
+/* A structure used to hold domain parameters.  */
+typedef struct
+{
+  gcry_mpi_t p;	    /* prime */
+  gcry_mpi_t q;	    /* group order */
+  gcry_mpi_t g;	    /* group generator */
+} dsa_domain_t;
+
+
+/* A sample 1024 bit DSA key used for the selftests.  */
+static const char sample_secret_key[] =
+"(private-key"
+" (dsa"
+"  (p #00AD7C0025BA1A15F775F3F2D673718391D00456978D347B33D7B49E7F32EDAB"
+"      96273899DD8B2BB46CD6ECA263FAF04A28903503D59062A8865D2AE8ADFB5191"
+"      CF36FFB562D0E2F5809801A1F675DAE59698A9E01EFE8D7DCFCA084F4C6F5A44"
+"      44D499A06FFAEA5E8EF5E01F2FD20A7B7EF3F6968AFBA1FB8D91F1559D52D8777B#)"
+"  (q #00EB7B5751D25EBBB7BD59D920315FD840E19AEBF9#)"
+"  (g #1574363387FDFD1DDF38F4FBE135BB20C7EE4772FB94C337AF86EA8E49666503"
+"      AE04B6BE81A2F8DD095311E0217ACA698A11E6C5D33CCDAE71498ED35D13991E"
+"      B02F09AB40BD8F4C5ED8C75DA779D0AE104BC34C960B002377068AB4B5A1F984"
+"      3FBA91F537F1B7CAC4D8DD6D89B0D863AF7025D549F9C765D2FC07EE208F8D15#)"
+"  (y #64B11EF8871BE4AB572AA810D5D3CA11A6CDBC637A8014602C72960DB135BF46"
+"      A1816A724C34F87330FC9E187C5D66897A04535CC2AC9164A7150ABFA8179827"
+"      6E45831AB811EEE848EBB24D9F5F2883B6E5DDC4C659DEF944DCFD80BF4D0A20"
+"      42CAA7DC289F0C5A9D155F02D3D551DB741A81695B74D4C8F477F9C7838EB0FB#)"
+"  (x #11D54E4ADBD3034160F2CED4B7CD292A4EBF3EC0#)))";
+/* A sample 1024 bit DSA key used for the selftests (public only).  */
+static const char sample_public_key[] = 
+"(public-key"
+" (dsa"
+"  (p #00AD7C0025BA1A15F775F3F2D673718391D00456978D347B33D7B49E7F32EDAB"
+"      96273899DD8B2BB46CD6ECA263FAF04A28903503D59062A8865D2AE8ADFB5191"
+"      CF36FFB562D0E2F5809801A1F675DAE59698A9E01EFE8D7DCFCA084F4C6F5A44"
+"      44D499A06FFAEA5E8EF5E01F2FD20A7B7EF3F6968AFBA1FB8D91F1559D52D8777B#)"
+"  (q #00EB7B5751D25EBBB7BD59D920315FD840E19AEBF9#)"
+"  (g #1574363387FDFD1DDF38F4FBE135BB20C7EE4772FB94C337AF86EA8E49666503"
+"      AE04B6BE81A2F8DD095311E0217ACA698A11E6C5D33CCDAE71498ED35D13991E"
+"      B02F09AB40BD8F4C5ED8C75DA779D0AE104BC34C960B002377068AB4B5A1F984"
+"      3FBA91F537F1B7CAC4D8DD6D89B0D863AF7025D549F9C765D2FC07EE208F8D15#)"
+"  (y #64B11EF8871BE4AB572AA810D5D3CA11A6CDBC637A8014602C72960DB135BF46"
+"      A1816A724C34F87330FC9E187C5D66897A04535CC2AC9164A7150ABFA8179827"
+"      6E45831AB811EEE848EBB24D9F5F2883B6E5DDC4C659DEF944DCFD80BF4D0A20"
+"      42CAA7DC289F0C5A9D155F02D3D551DB741A81695B74D4C8F477F9C7838EB0FB#)))";
+
+
+
+
+static gcry_mpi_t gen_k (gcry_mpi_t q);
+static int test_keys (DSA_secret_key *sk, unsigned int qbits);
+static int check_secret_key (DSA_secret_key *sk);
+static gpg_err_code_t generate (DSA_secret_key *sk,
+                                unsigned int nbits,
+                                unsigned int qbits,
+                                int transient_key,
+                                dsa_domain_t *domain,
+                                gcry_mpi_t **ret_factors);
+static void sign (gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t input,
+                  DSA_secret_key *skey);
+static int verify (gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t input,
+                   DSA_public_key *pkey);
+
+static void (*progress_cb) (void *,const char *, int, int, int );
+static void *progress_cb_data;
+
+
+void
+_gcry_register_pk_dsa_progress (void (*cb) (void *, const char *,
+                                            int, int, int),
+				void *cb_data)
+{
+  progress_cb = cb;
+  progress_cb_data = cb_data;
+}
+
+
+static void
+progress (int c)
+{
+  if (progress_cb)
+    progress_cb (progress_cb_data, "pk_dsa", c, 0, 0);
+}
+
+
+/*
+ * Generate a random secret exponent k less than q.
+ */
+static gcry_mpi_t
+gen_k( gcry_mpi_t q )
+{
+  gcry_mpi_t k = mpi_alloc_secure( mpi_get_nlimbs(q) );
+  unsigned int nbits = mpi_get_nbits(q);
+  unsigned int nbytes = (nbits+7)/8;
+  char *rndbuf = NULL;
+
+  if ( DBG_CIPHER )
+    log_debug("choosing a random k ");
+  for (;;) 
+    {
+      if( DBG_CIPHER )
+        progress('.');
+
+      if ( !rndbuf || nbits < 32 ) 
+        {
+          gcry_free(rndbuf);
+          rndbuf = gcry_random_bytes_secure( (nbits+7)/8, GCRY_STRONG_RANDOM );
+	}
+      else
+        { /* Change only some of the higher bits.  We could improve
+	     this by directly requesting more memory at the first call
+	     to get_random_bytes() and use this the here maybe it is
+	     easier to do this directly in random.c. */
+          char *pp = gcry_random_bytes_secure( 4, GCRY_STRONG_RANDOM );
+          memcpy( rndbuf,pp, 4 );
+          gcry_free(pp);
+	}
+      _gcry_mpi_set_buffer( k, rndbuf, nbytes, 0 );
+      if ( mpi_test_bit( k, nbits-1 ) )
+        mpi_set_highbit( k, nbits-1 );
+      else
+        {
+          mpi_set_highbit( k, nbits-1 );
+          mpi_clear_bit( k, nbits-1 );
+	}
+
+      if( !(mpi_cmp( k, q ) < 0) ) /* check: k < q */
+        {	
+          if( DBG_CIPHER )
+            progress('+');
+          continue; /* no  */
+        }
+      if( !(mpi_cmp_ui( k, 0 ) > 0) )  /* check: k > 0 */
+        {
+          if( DBG_CIPHER )
+            progress('-');
+          continue; /* no */
+        }
+      break;	/* okay */
+    }
+  gcry_free(rndbuf);
+  if( DBG_CIPHER )
+    progress('\n');
+  
+  return k;
+}
+
+
+/* Check that a freshly generated key actually works.  Returns 0 on success. */
+static int
+test_keys (DSA_secret_key *sk, unsigned int qbits)
+{
+  int result = -1;  /* Default to failure.  */
+  DSA_public_key pk;
+  gcry_mpi_t data  = gcry_mpi_new (qbits);
+  gcry_mpi_t sig_a = gcry_mpi_new (qbits);
+  gcry_mpi_t sig_b = gcry_mpi_new (qbits);
+
+  /* Put the relevant parameters into a public key structure.  */
+  pk.p = sk->p;
+  pk.q = sk->q;
+  pk.g = sk->g;
+  pk.y = sk->y;
+
+  /* Create a random plaintext.  */
+  gcry_mpi_randomize (data, qbits, GCRY_WEAK_RANDOM);
+
+  /* Sign DATA using the secret key.  */
+  sign (sig_a, sig_b, data, sk);
+
+  /* Verify the signature using the public key.  */
+  if ( !verify (sig_a, sig_b, data, &pk) )
+    goto leave; /* Signature does not match.  */
+
+  /* Modify the data and check that the signing fails.  */
+  gcry_mpi_add_ui (data, data, 1);
+  if ( verify (sig_a, sig_b, data, &pk) )
+    goto leave; /* Signature matches but should not.  */
+
+  result = 0; /* The test succeeded.  */
+
+ leave:
+  gcry_mpi_release (sig_b);
+  gcry_mpi_release (sig_a);
+  gcry_mpi_release (data);
+  return result;
+}
+
+
+
+/*
+   Generate a DSA key pair with a key of size NBITS.  If transient_key
+   is true the key is generated using the standard RNG and not the
+   very secure one.
+
+   Returns: 2 structures filled with all needed values
+ 	    and an array with the n-1 factors of (p-1)
+ */
+static gpg_err_code_t
+generate (DSA_secret_key *sk, unsigned int nbits, unsigned int qbits,
+          int transient_key, dsa_domain_t *domain, gcry_mpi_t **ret_factors )
+{
+  gcry_mpi_t p;    /* the prime */
+  gcry_mpi_t q;    /* the 160 bit prime factor */
+  gcry_mpi_t g;    /* the generator */
+  gcry_mpi_t y;    /* g^x mod p */
+  gcry_mpi_t x;    /* the secret exponent */
+  gcry_mpi_t h, e;  /* helper */
+  unsigned char *rndbuf;
+  gcry_random_level_t random_level;
+
+  if (qbits)
+    ; /* Caller supplied qbits.  Use this value.  */
+  else if ( nbits >= 512 && nbits <= 1024 )
+    qbits = 160;
+  else if ( nbits == 2048 )
+    qbits = 224;
+  else if ( nbits == 3072 )
+    qbits = 256;
+  else if ( nbits == 7680 )
+    qbits = 384;
+  else if ( nbits == 15360 )
+    qbits = 512;
+  else
+    return GPG_ERR_INV_VALUE;
+
+  if (qbits < 160 || qbits > 512 || (qbits%8) )
+    return GPG_ERR_INV_VALUE;
+  if (nbits < 2*qbits || nbits > 15360)
+    return GPG_ERR_INV_VALUE;
+
+  if (fips_mode ())
+    {
+      if (nbits < 1024)
+        return GPG_ERR_INV_VALUE;
+      if (transient_key)
+        return GPG_ERR_INV_VALUE;
+    }
+
+  if (domain->p && domain->q && domain->g)
+    {
+      /* Domain parameters are given; use them.  */
+      p = mpi_copy (domain->p);
+      q = mpi_copy (domain->q);
+      g = mpi_copy (domain->g);
+      gcry_assert (mpi_get_nbits (p) == nbits);
+      gcry_assert (mpi_get_nbits (q) == qbits);
+      h = mpi_alloc (0);
+      e = NULL;
+    }
+  else
+    {
+      /* Generate new domain parameters.  */
+      p = _gcry_generate_elg_prime (1, nbits, qbits, NULL, ret_factors);
+      /* Get q out of factors.  */
+      q = mpi_copy ((*ret_factors)[0]);
+      gcry_assert (mpi_get_nbits (q) == qbits);
+
+      /* Find a generator g (h and e are helpers).
+         e = (p-1)/q */
+      e = mpi_alloc (mpi_get_nlimbs (p));
+      mpi_sub_ui (e, p, 1);
+      mpi_fdiv_q (e, e, q);
+      g = mpi_alloc (mpi_get_nlimbs (p));
+      h = mpi_alloc_set_ui (1); /* (We start with 2.) */
+      do
+        {
+          mpi_add_ui (h, h, 1);
+          /* g = h^e mod p */
+          gcry_mpi_powm (g, h, e, p);
+        } 
+      while (!mpi_cmp_ui (g, 1));  /* Continue until g != 1. */
+    }
+
+  /* Select a random number X with the property:
+   *	 0 < x < q-1
+   * This must be a very good random number because this is the secret
+   * part.  The random quality depends on the transient_key flag.  */
+  random_level = transient_key ? GCRY_STRONG_RANDOM : GCRY_VERY_STRONG_RANDOM;
+  if (DBG_CIPHER)
+    log_debug("choosing a random x%s", transient_key? " (transient-key)":"");
+  gcry_assert( qbits >= 160 );
+  x = mpi_alloc_secure( mpi_get_nlimbs(q) );
+  mpi_sub_ui( h, q, 1 );  /* put q-1 into h */
+  rndbuf = NULL;
+  do 
+    {
+      if( DBG_CIPHER )
+        progress('.');
+      if( !rndbuf )
+        rndbuf = gcry_random_bytes_secure ((qbits+7)/8, random_level);
+      else 
+        { /* Change only some of the higher bits (= 2 bytes)*/
+          char *r = gcry_random_bytes_secure (2, random_level);
+          memcpy(rndbuf, r, 2 );
+          gcry_free(r);
+        }
+
+      _gcry_mpi_set_buffer( x, rndbuf, (qbits+7)/8, 0 );
+      mpi_clear_highbit( x, qbits+1 );
+    } 
+  while ( !( mpi_cmp_ui( x, 0 )>0 && mpi_cmp( x, h )<0 ) );
+  gcry_free(rndbuf);
+  mpi_free( e );
+  mpi_free( h );
+
+  /* y = g^x mod p */
+  y = mpi_alloc( mpi_get_nlimbs(p) );
+  gcry_mpi_powm( y, g, x, p );
+
+  if( DBG_CIPHER ) 
+    {
+      progress('\n');
+      log_mpidump("dsa  p", p );
+      log_mpidump("dsa  q", q );
+      log_mpidump("dsa  g", g );
+      log_mpidump("dsa  y", y );
+      log_mpidump("dsa  x", x );
+    }
+
+  /* Copy the stuff to the key structures. */
+  sk->p = p;
+  sk->q = q;
+  sk->g = g;
+  sk->y = y;
+  sk->x = x;
+
+  /* Now we can test our keys (this should never fail!). */
+  if ( test_keys (sk, qbits) )
+    {
+      gcry_mpi_release (sk->p); sk->p = NULL;
+      gcry_mpi_release (sk->q); sk->q = NULL;
+      gcry_mpi_release (sk->g); sk->g = NULL;
+      gcry_mpi_release (sk->y); sk->y = NULL;
+      gcry_mpi_release (sk->x); sk->x = NULL;
+      fips_signal_error ("self-test after key generation failed");
+      return GPG_ERR_SELFTEST_FAILED;
+    }
+  return 0;
+}
+
+
+/* Generate a DSA key pair with a key of size NBITS using the
+   algorithm given in FIPS-186-3.  If USE_FIPS186_2 is true,
+   FIPS-186-2 is used and thus the length is restricted to 1024/160.
+   If DERIVEPARMS is not NULL it may contain a seed value.  If domain
+   parameters are specified in DOMAIN, DERIVEPARMS may not be given
+   and NBITS and QBITS must match the specified domain parameters.  */
+static gpg_err_code_t
+generate_fips186 (DSA_secret_key *sk, unsigned int nbits, unsigned int qbits,
+                  gcry_sexp_t deriveparms, int use_fips186_2,
+                  dsa_domain_t *domain,
+                  int *r_counter, void **r_seed, size_t *r_seedlen,
+                  gcry_mpi_t *r_h)
+{
+  gpg_err_code_t ec;
+  struct {
+    gcry_sexp_t sexp;
+    const void *seed;
+    size_t seedlen;
+  } initial_seed = { NULL, NULL, 0 };
+  gcry_mpi_t prime_q = NULL; 
+  gcry_mpi_t prime_p = NULL; 
+  gcry_mpi_t value_g = NULL; /* The generator. */
+  gcry_mpi_t value_y = NULL; /* g^x mod p */
+  gcry_mpi_t value_x = NULL; /* The secret exponent. */
+  gcry_mpi_t value_h = NULL; /* Helper.  */
+  gcry_mpi_t value_e = NULL; /* Helper.  */
+
+  /* Preset return values.  */
+  *r_counter = 0;
+  *r_seed = NULL;
+  *r_seedlen = 0;
+  *r_h = NULL;
+
+  /* Derive QBITS from NBITS if requested  */
+  if (!qbits)
+    {
+      if (nbits == 1024)
+        qbits = 160;
+      else if (nbits == 2048)
+        qbits = 224;
+      else if (nbits == 3072)
+        qbits = 256;
+    }
+
+  /* Check that QBITS and NBITS match the standard.  Note that FIPS
+     186-3 uses N for QBITS and L for NBITS.  */
+  if (nbits == 1024 && qbits == 160)
+    ;
+  else if (nbits == 2048 && qbits == 224)
+    ;
+  else if (nbits == 2048 && qbits == 256)
+    ;
+  else if (nbits == 3072 && qbits == 256)
+    ;
+  else
+    return GPG_ERR_INV_VALUE;
+
+  if (domain->p && domain->q && domain->g)
+    {
+      /* Domain parameters are given; use them.  */
+      prime_p = mpi_copy (domain->p);
+      prime_q = mpi_copy (domain->q);
+      value_g = mpi_copy (domain->g);
+      gcry_assert (mpi_get_nbits (prime_p) == nbits);
+      gcry_assert (mpi_get_nbits (prime_q) == qbits);
+      gcry_assert (!deriveparms);
+      ec = 0;
+    }
+  else
+    {
+      /* Generate new domain parameters.  */
+
+      /* Get an initial seed value.  */
+      if (deriveparms)
+        {
+          initial_seed.sexp = gcry_sexp_find_token (deriveparms, "seed", 0);
+          if (initial_seed.sexp)
+            initial_seed.seed = gcry_sexp_nth_data (initial_seed.sexp, 1,
+                                                    &initial_seed.seedlen);
+        }
+      
+      /* Fixme: Enable 186-3 after it has been approved and after fixing
+         the generation function.  */
+      /*   if (use_fips186_2) */
+      (void)use_fips186_2;
+      ec = _gcry_generate_fips186_2_prime (nbits, qbits, 
+                                           initial_seed.seed, 
+                                           initial_seed.seedlen,
+                                           &prime_q, &prime_p, 
+                                           r_counter,
+                                           r_seed, r_seedlen);
+      /*   else */
+      /*     ec = _gcry_generate_fips186_3_prime (nbits, qbits, NULL, 0, */
+      /*                                          &prime_q, &prime_p, */
+      /*                                          r_counter, */
+      /*                                          r_seed, r_seedlen, NULL); */
+      gcry_sexp_release (initial_seed.sexp);
+      if (ec)
+        goto leave;
+
+      /* Find a generator g (h and e are helpers).
+         e = (p-1)/q */
+      value_e = mpi_alloc_like (prime_p);
+      mpi_sub_ui (value_e, prime_p, 1);
+      mpi_fdiv_q (value_e, value_e, prime_q );
+      value_g = mpi_alloc_like (prime_p);
+      value_h = mpi_alloc_set_ui (1); 
+      do
+        {
+          mpi_add_ui (value_h, value_h, 1);
+          /* g = h^e mod p */
+          mpi_powm (value_g, value_h, value_e, prime_p);
+        } 
+      while (!mpi_cmp_ui (value_g, 1));  /* Continue until g != 1.  */
+    }
+
+
+  /* Select a random number x with:  0 < x < q  */
+  value_x = gcry_mpi_snew (qbits);
+  do 
+    {
+      if( DBG_CIPHER )
+        progress('.');
+      gcry_mpi_randomize (value_x, qbits, GCRY_VERY_STRONG_RANDOM);
+      mpi_clear_highbit (value_x, qbits+1);
+    } 
+  while (!(mpi_cmp_ui (value_x, 0) > 0 && mpi_cmp (value_x, prime_q) < 0));
+
+  /* y = g^x mod p */
+  value_y = mpi_alloc_like (prime_p);
+  gcry_mpi_powm (value_y, value_g, value_x, prime_p);
+
+  if (DBG_CIPHER) 
+    {
+      progress('\n');
+      log_mpidump("dsa  p", prime_p );
+      log_mpidump("dsa  q", prime_q );
+      log_mpidump("dsa  g", value_g );
+      log_mpidump("dsa  y", value_y );
+      log_mpidump("dsa  x", value_x );
+      log_mpidump("dsa  h", value_h );
+    }
+
+  /* Copy the stuff to the key structures. */
+  sk->p = prime_p; prime_p = NULL;
+  sk->q = prime_q; prime_q = NULL;
+  sk->g = value_g; value_g = NULL;
+  sk->y = value_y; value_y = NULL;
+  sk->x = value_x; value_x = NULL;
+  *r_h = value_h; value_h = NULL;
+
+ leave:
+  gcry_mpi_release (prime_p);
+  gcry_mpi_release (prime_q);
+  gcry_mpi_release (value_g);
+  gcry_mpi_release (value_y);
+  gcry_mpi_release (value_x);
+  gcry_mpi_release (value_h);
+  gcry_mpi_release (value_e);
+
+  /* As a last step test this keys (this should never fail of course). */
+  if (!ec && test_keys (sk, qbits) )
+    {
+      gcry_mpi_release (sk->p); sk->p = NULL;
+      gcry_mpi_release (sk->q); sk->q = NULL;
+      gcry_mpi_release (sk->g); sk->g = NULL;
+      gcry_mpi_release (sk->y); sk->y = NULL;
+      gcry_mpi_release (sk->x); sk->x = NULL;
+      fips_signal_error ("self-test after key generation failed");
+      ec = GPG_ERR_SELFTEST_FAILED;
+    }
+
+  if (ec)
+    {
+      *r_counter = 0;
+      gcry_free (*r_seed); *r_seed = NULL;
+      *r_seedlen = 0;
+      gcry_mpi_release (*r_h); *r_h = NULL;
+    }
+
+  return ec;
+}
+
+
+
+/*
+   Test whether the secret key is valid.
+   Returns: if this is a valid key.
+ */
+static int
+check_secret_key( DSA_secret_key *sk )
+{
+  int rc;
+  gcry_mpi_t y = mpi_alloc( mpi_get_nlimbs(sk->y) );
+
+  gcry_mpi_powm( y, sk->g, sk->x, sk->p );
+  rc = !mpi_cmp( y, sk->y );
+  mpi_free( y );
+  return rc;
+}
+
+
+
+/*
+   Make a DSA signature from HASH and put it into r and s.
+ */
+static void
+sign(gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t hash, DSA_secret_key *skey )
+{
+  gcry_mpi_t k;
+  gcry_mpi_t kinv;
+  gcry_mpi_t tmp;
+
+  /* Select a random k with 0 < k < q */
+  k = gen_k( skey->q );
+
+  /* r = (a^k mod p) mod q */
+  gcry_mpi_powm( r, skey->g, k, skey->p );
+  mpi_fdiv_r( r, r, skey->q );
+
+  /* kinv = k^(-1) mod q */
+  kinv = mpi_alloc( mpi_get_nlimbs(k) );
+  mpi_invm(kinv, k, skey->q );
+
+  /* s = (kinv * ( hash + x * r)) mod q */
+  tmp = mpi_alloc( mpi_get_nlimbs(skey->p) );
+  mpi_mul( tmp, skey->x, r );
+  mpi_add( tmp, tmp, hash );
+  mpi_mulm( s , kinv, tmp, skey->q );
+
+  mpi_free(k);
+  mpi_free(kinv);
+  mpi_free(tmp);
+}
+
+
+/*
+   Returns true if the signature composed from R and S is valid.
+ */
+static int
+verify (gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t hash, DSA_public_key *pkey )
+{
+  int rc;
+  gcry_mpi_t w, u1, u2, v;
+  gcry_mpi_t base[3];
+  gcry_mpi_t ex[3];
+
+  if( !(mpi_cmp_ui( r, 0 ) > 0 && mpi_cmp( r, pkey->q ) < 0) )
+    return 0; /* assertion	0 < r < q  failed */
+  if( !(mpi_cmp_ui( s, 0 ) > 0 && mpi_cmp( s, pkey->q ) < 0) )
+    return 0; /* assertion	0 < s < q  failed */
+
+  w  = mpi_alloc( mpi_get_nlimbs(pkey->q) );
+  u1 = mpi_alloc( mpi_get_nlimbs(pkey->q) );
+  u2 = mpi_alloc( mpi_get_nlimbs(pkey->q) );
+  v  = mpi_alloc( mpi_get_nlimbs(pkey->p) );
+
+  /* w = s^(-1) mod q */
+  mpi_invm( w, s, pkey->q );
+
+  /* u1 = (hash * w) mod q */
+  mpi_mulm( u1, hash, w, pkey->q );
+
+  /* u2 = r * w mod q  */
+  mpi_mulm( u2, r, w, pkey->q );
+
+  /* v =  g^u1 * y^u2 mod p mod q */
+  base[0] = pkey->g; ex[0] = u1;
+  base[1] = pkey->y; ex[1] = u2;
+  base[2] = NULL;    ex[2] = NULL;
+  mpi_mulpowm( v, base, ex, pkey->p );
+  mpi_fdiv_r( v, v, pkey->q );
+
+  rc = !mpi_cmp( v, r );
+
+  mpi_free(w);
+  mpi_free(u1);
+  mpi_free(u2);
+  mpi_free(v);
+
+  return rc;
+}
+
+
+/*********************************************
+ **************  interface  ******************
+ *********************************************/
+
+static gcry_err_code_t
+dsa_generate_ext (int algo, unsigned int nbits, unsigned long evalue,
+                  const gcry_sexp_t genparms,
+                  gcry_mpi_t *skey, gcry_mpi_t **retfactors,
+                  gcry_sexp_t *r_extrainfo)
+{
+  gpg_err_code_t ec;
+  DSA_secret_key sk;
+  gcry_sexp_t l1;
+  unsigned int qbits = 0;
+  gcry_sexp_t deriveparms = NULL;
+  gcry_sexp_t seedinfo = NULL;
+  int transient_key = 0;
+  int use_fips186_2 = 0;
+  int use_fips186 = 0;
+  dsa_domain_t domain;
+ 
+  (void)algo;    /* No need to check it.  */
+  (void)evalue;  /* Not required for DSA. */
+
+  memset (&domain, 0, sizeof domain);
+
+  if (genparms)
+    {
+      gcry_sexp_t domainsexp;
+  
+      /* Parse the optional qbits element.  */
+      l1 = gcry_sexp_find_token (genparms, "qbits", 0);
+      if (l1)
+        {
+          char buf[50];
+          const char *s;
+          size_t n;
+          
+          s = gcry_sexp_nth_data (l1, 1, &n);
+          if (!s || n >= DIM (buf) - 1 )
+            {
+              gcry_sexp_release (l1);
+              return GPG_ERR_INV_OBJ; /* No value or value too large.  */
+            }
+          memcpy (buf, s, n);
+          buf[n] = 0;
+          qbits = (unsigned int)strtoul (buf, NULL, 0);
+          gcry_sexp_release (l1);
+        }
+
+      /* Parse the optional transient-key flag.  */
+      l1 = gcry_sexp_find_token (genparms, "transient-key", 0);
+      if (l1)
+        {
+          transient_key = 1;
+          gcry_sexp_release (l1);
+        }
+
+      /* Get the optional derive parameters.  */
+      deriveparms = gcry_sexp_find_token (genparms, "derive-parms", 0);
+
+      /* Parse the optional "use-fips186" flags.  */
+      l1 = gcry_sexp_find_token (genparms, "use-fips186", 0);
+      if (l1)
+        {
+          use_fips186 = 1;
+          gcry_sexp_release (l1);
+        }
+      l1 = gcry_sexp_find_token (genparms, "use-fips186-2", 0);
+      if (l1)
+        {
+          use_fips186_2 = 1;
+          gcry_sexp_release (l1);
+        }
+
+      /* Check whether domain parameters are given.  */
+      domainsexp = gcry_sexp_find_token (genparms, "domain", 0);
+      if (domainsexp)
+        {
+          /* DERIVEPARMS can't be used together with domain
+             parameters.  NBITS abnd QBITS may not be specified
+             because there values are derived from the domain
+             parameters.  */
+          if (deriveparms || qbits || nbits)
+            {
+              gcry_sexp_release (domainsexp);
+              gcry_sexp_release (deriveparms);
+              return GPG_ERR_INV_VALUE;
+            }
+          
+          /* Put all domain parameters into the domain object.  */
+          l1 = gcry_sexp_find_token (domainsexp, "p", 0);
+          domain.p = gcry_sexp_nth_mpi (l1, 1, GCRYMPI_FMT_USG);
+          gcry_sexp_release (l1);
+          l1 = gcry_sexp_find_token (domainsexp, "q", 0);
+          domain.q = gcry_sexp_nth_mpi (l1, 1, GCRYMPI_FMT_USG);
+          gcry_sexp_release (l1);
+          l1 = gcry_sexp_find_token (domainsexp, "g", 0);
+          domain.g = gcry_sexp_nth_mpi (l1, 1, GCRYMPI_FMT_USG);
+          gcry_sexp_release (l1);
+          gcry_sexp_release (domainsexp);
+
+          /* Check that all domain parameters are available.  */
+          if (!domain.p || !domain.q || !domain.g)
+            {
+              gcry_mpi_release (domain.p);
+              gcry_mpi_release (domain.q);
+              gcry_mpi_release (domain.g);
+              gcry_sexp_release (deriveparms);
+              return GPG_ERR_MISSING_VALUE;
+            }
+
+          /* Get NBITS and QBITS from the domain parameters.  */
+          nbits = mpi_get_nbits (domain.p);
+          qbits = mpi_get_nbits (domain.q);
+        }
+    }
+
+  if (deriveparms || use_fips186 || use_fips186_2 || fips_mode ())
+    {
+      int counter;
+      void *seed;
+      size_t seedlen;
+      gcry_mpi_t h_value;
+
+      ec = generate_fips186 (&sk, nbits, qbits, deriveparms, use_fips186_2,
+                             &domain,
+                             &counter, &seed, &seedlen, &h_value);
+      gcry_sexp_release (deriveparms);
+      if (!ec && h_value)
+        {
+          /* Format the seed-values unless domain parameters are used
+             for which a H_VALUE of NULL is an indication.  */
+          ec = gpg_err_code (gcry_sexp_build 
+                             (&seedinfo, NULL,
+                              "(seed-values(counter %d)(seed %b)(h %m))",
+                              counter, (int)seedlen, seed, h_value));
+          if (ec)
+            {
+              gcry_mpi_release (sk.p); sk.p = NULL;
+              gcry_mpi_release (sk.q); sk.q = NULL;
+              gcry_mpi_release (sk.g); sk.g = NULL;
+              gcry_mpi_release (sk.y); sk.y = NULL;
+              gcry_mpi_release (sk.x); sk.x = NULL;
+            }
+          gcry_free (seed);
+          gcry_mpi_release (h_value);
+        }
+    }
+  else
+    {
+      ec = generate (&sk, nbits, qbits, transient_key, &domain, retfactors);
+    }
+
+  gcry_mpi_release (domain.p);
+  gcry_mpi_release (domain.q);
+  gcry_mpi_release (domain.g);
+
+  if (!ec)
+    {
+      skey[0] = sk.p;
+      skey[1] = sk.q;
+      skey[2] = sk.g;
+      skey[3] = sk.y;
+      skey[4] = sk.x;
+
+      if (!r_extrainfo)
+        {
+          /* Old style interface - return the factors - if any - at
+             retfactors.  */
+        }
+      else if (!*retfactors && !seedinfo)
+        {
+          /* No factors and no seedinfo, thus there is nothing to return.  */
+          *r_extrainfo = NULL;
+        }
+      else
+        {
+          /* Put the factors into extrainfo and set retfactors to NULL
+             to make use of the new interface.  Note that the factors
+             are not confidential thus we can store them in standard
+             memory.  */
+          int nfactors, i, j;
+          char *p;
+          char *format = NULL;
+          void **arg_list = NULL;
+
+          for (nfactors=0; *retfactors && (*retfactors)[nfactors]; nfactors++)
+            ;
+          /* Allocate space for the format string:
+               "(misc-key-info%S(pm1-factors%m))"
+             with one "%m" for each factor and construct it.  */
+          format = gcry_malloc (50 + 2*nfactors);
+          if (!format)
+            ec = gpg_err_code_from_syserror ();
+          else
+            {
+              p = stpcpy (format, "(misc-key-info");
+              if (seedinfo)
+                p = stpcpy (p, "%S");
+              if (nfactors)
+                {
+                  p = stpcpy (p, "(pm1-factors");
+                  for (i=0; i < nfactors; i++)
+                    p = stpcpy (p, "%m");
+                  p = stpcpy (p, ")");
+                }
+              p = stpcpy (p, ")");
+              
+              /* Allocate space for the list of factors plus one for
+                 an S-expression plus an extra NULL entry for safety
+                 and fill it with the factors.  */
+              arg_list = gcry_calloc (nfactors+1+1, sizeof *arg_list);
+              if (!arg_list)
+                ec = gpg_err_code_from_syserror ();
+              else
+                {
+                  i = 0;
+                  if (seedinfo)
+                    arg_list[i++] = &seedinfo;
+                  for (j=0; j < nfactors; j++)
+                    arg_list[i++] = (*retfactors) + j;
+                  arg_list[i] = NULL;
+                  
+                  ec = gpg_err_code (gcry_sexp_build_array 
+                                     (r_extrainfo, NULL, format, arg_list));
+                }
+            }
+
+          gcry_free (arg_list);
+          gcry_free (format);
+          for (i=0; i < nfactors; i++)
+            {
+              gcry_mpi_release ((*retfactors)[i]);
+              (*retfactors)[i] = NULL;
+            }
+          gcry_free (*retfactors);
+          *retfactors = NULL;
+          if (ec)
+            {
+              for (i=0; i < 5; i++)
+                {
+                  gcry_mpi_release (skey[i]);
+                  skey[i] = NULL;
+                }
+            }
+        }
+    }
+
+  gcry_sexp_release (seedinfo);
+  return ec;
+}
+
+
+static gcry_err_code_t
+dsa_generate (int algo, unsigned int nbits, unsigned long evalue,
+              gcry_mpi_t *skey, gcry_mpi_t **retfactors)
+{
+  (void)evalue;
+  return dsa_generate_ext (algo, nbits, 0, NULL, skey, retfactors, NULL);
+}
+
+
+
+static gcry_err_code_t
+dsa_check_secret_key (int algo, gcry_mpi_t *skey)
+{
+  gcry_err_code_t err = GPG_ERR_NO_ERROR;
+  DSA_secret_key sk;
+
+  (void)algo;
+
+  if ((! skey[0]) || (! skey[1]) || (! skey[2]) || (! skey[3]) || (! skey[4]))
+    err = GPG_ERR_BAD_MPI;
+  else
+    {
+      sk.p = skey[0];
+      sk.q = skey[1];
+      sk.g = skey[2];
+      sk.y = skey[3];
+      sk.x = skey[4];
+      if (! check_secret_key (&sk))
+	err = GPG_ERR_BAD_SECKEY;
+    }
+
+  return err;
+}
+
+
+static gcry_err_code_t
+dsa_sign (int algo, gcry_mpi_t *resarr, gcry_mpi_t data, gcry_mpi_t *skey)
+{
+  gcry_err_code_t err = GPG_ERR_NO_ERROR;
+  DSA_secret_key sk;
+
+  (void)algo;
+
+  if ((! data)
+      || (! skey[0]) || (! skey[1]) || (! skey[2])
+      || (! skey[3]) || (! skey[4]))
+    err = GPG_ERR_BAD_MPI;
+  else
+    {
+      sk.p = skey[0];
+      sk.q = skey[1];
+      sk.g = skey[2];
+      sk.y = skey[3];
+      sk.x = skey[4];
+      resarr[0] = mpi_alloc (mpi_get_nlimbs (sk.p));
+      resarr[1] = mpi_alloc (mpi_get_nlimbs (sk.p));
+      sign (resarr[0], resarr[1], data, &sk);
+    }
+  return err;
+}
+
+static gcry_err_code_t
+dsa_verify (int algo, gcry_mpi_t hash, gcry_mpi_t *data, gcry_mpi_t *pkey,
+            int (*cmp) (void *, gcry_mpi_t), void *opaquev)
+{
+  gcry_err_code_t err = GPG_ERR_NO_ERROR;
+  DSA_public_key pk;
+
+  (void)algo;
+  (void)cmp;
+  (void)opaquev;
+
+  if ((! data[0]) || (! data[1]) || (! hash)
+      || (! pkey[0]) || (! pkey[1]) || (! pkey[2]) || (! pkey[3]))
+    err = GPG_ERR_BAD_MPI;
+  else
+    {
+      pk.p = pkey[0];
+      pk.q = pkey[1];
+      pk.g = pkey[2];
+      pk.y = pkey[3];
+      if (! verify (data[0], data[1], hash, &pk))
+	err = GPG_ERR_BAD_SIGNATURE;
+    }
+  return err;
+}
+
+
+static unsigned int
+dsa_get_nbits (int algo, gcry_mpi_t *pkey)
+{
+  (void)algo;
+
+  return mpi_get_nbits (pkey[0]);
+}
+
+
+
+/* 
+     Self-test section.
+ */
+
+static const char *
+selftest_sign_1024 (gcry_sexp_t pkey, gcry_sexp_t skey)
+{
+  static const char sample_data[] = 
+    "(data (flags pkcs1)"
+    " (hash sha1 #a0b1c2d3e4f500102030405060708090a1b2c3d4#))";
+  static const char sample_data_bad[] = 
+    "(data (flags pkcs1)"
+    " (hash sha1 #a0b1c2d3e4f510102030405060708090a1b2c3d4#))";
+
+  const char *errtxt = NULL;
+  gcry_error_t err;
+  gcry_sexp_t data = NULL;
+  gcry_sexp_t data_bad = NULL;
+  gcry_sexp_t sig = NULL;
+
+  err = gcry_sexp_sscan (&data, NULL,
+                         sample_data, strlen (sample_data));
+  if (!err)
+    err = gcry_sexp_sscan (&data_bad, NULL, 
+                           sample_data_bad, strlen (sample_data_bad));
+  if (err)
+    {
+      errtxt = "converting data failed";
+      goto leave;
+    }
+
+  err = gcry_pk_sign (&sig, data, skey);
+  if (err)
+    {
+      errtxt = "signing failed";
+      goto leave;
+    }
+  err = gcry_pk_verify (sig, data, pkey);
+  if (err)
+    {
+      errtxt = "verify failed";
+      goto leave;
+    }
+  err = gcry_pk_verify (sig, data_bad, pkey);
+  if (gcry_err_code (err) != GPG_ERR_BAD_SIGNATURE)
+    {
+      errtxt = "bad signature not detected";
+      goto leave;
+    }
+
+
+ leave:
+  gcry_sexp_release (sig);
+  gcry_sexp_release (data_bad);
+  gcry_sexp_release (data);
+  return errtxt;
+}
+
+
+static gpg_err_code_t
+selftests_dsa (selftest_report_func_t report)
+{
+  const char *what;
+  const char *errtxt;
+  gcry_error_t err;
+  gcry_sexp_t skey = NULL;
+  gcry_sexp_t pkey = NULL;
+
+  /* Convert the S-expressions into the internal representation.  */
+  what = "convert";
+  err = gcry_sexp_sscan (&skey, NULL, 
+                         sample_secret_key, strlen (sample_secret_key));
+  if (!err)
+    err = gcry_sexp_sscan (&pkey, NULL, 
+                           sample_public_key, strlen (sample_public_key));
+  if (err)
+    {
+      errtxt = gcry_strerror (err);
+      goto failed;
+    }
+
+  what = "key consistency";
+  err = gcry_pk_testkey (skey);
+  if (err)
+    {
+      errtxt = gcry_strerror (err);
+      goto failed;
+    }
+
+  what = "sign";
+  errtxt = selftest_sign_1024 (pkey, skey);
+  if (errtxt)
+    goto failed;
+
+  gcry_sexp_release (pkey);
+  gcry_sexp_release (skey);
+  return 0; /* Succeeded. */
+
+ failed:
+  gcry_sexp_release (pkey);
+  gcry_sexp_release (skey);
+  if (report)
+    report ("pubkey", GCRY_PK_DSA, what, errtxt);
+  return GPG_ERR_SELFTEST_FAILED;
+}
+
+
+/* Run a full self-test for ALGO and return 0 on success.  */
+static gpg_err_code_t
+run_selftests (int algo, int extended, selftest_report_func_t report)
+{
+  gpg_err_code_t ec;
+
+  (void)extended;
+
+  switch (algo)
+    {
+    case GCRY_PK_DSA:
+      ec = selftests_dsa (report);
+      break;
+    default:
+      ec = GPG_ERR_PUBKEY_ALGO;
+      break;
+        
+    }
+  return ec;
+}
+
+
+
+
+static const char *dsa_names[] =
+  {
+    "dsa",
+    "openpgp-dsa",
+    NULL,
+  };
+
+gcry_pk_spec_t _gcry_pubkey_spec_dsa =
+  {
+    "DSA", dsa_names, 
+    "pqgy", "pqgyx", "", "rs", "pqgy",
+    GCRY_PK_USAGE_SIGN,
+    dsa_generate,
+    dsa_check_secret_key,
+    NULL,
+    NULL,
+    dsa_sign,
+    dsa_verify,
+    dsa_get_nbits
+  };
+pk_extra_spec_t _gcry_pubkey_extraspec_dsa = 
+  {
+    run_selftests,
+    dsa_generate_ext
+  };
+