Add gcry_pubkey_get_sexp.

* src/gcrypt.h.in (GCRY_PK_GET_PUBKEY): New.
(GCRY_PK_GET_SECKEY): New.
(gcry_pubkey_get_sexp): New.
* src/visibility.c (gcry_pubkey_get_sexp): New.
* src/visibility.h (gcry_pubkey_get_sexp): Mark visible.
* src/libgcrypt.def, src/libgcrypt.vers: Add new function.
* cipher/pubkey-internal.h: New.
* cipher/Makefile.am (libcipher_la_SOURCES): Add new file.
* cipher/ecc.c: Include pubkey-internal.h
(_gcry_pk_ecc_get_sexp): New.
* cipher/pubkey.c: Include pubkey-internal.h and context.h.
(_gcry_pubkey_get_sexp): New.
* src/context.c (_gcry_ctx_find_pointer): New.
* src/cipher-proto.h: Add _gcry_pubkey_get_sexp.
* tests/t-mpi-point.c (print_sexp): New.
(context_param, basic_ec_math_simplified): Add tests for the new
function.

* configure.ac (NEED_GPG_ERROR_VERSION): Set to 1.11.
(AH_BOTTOM) Add error codes from gpg-error 1.12
* src/g10lib.h (fips_not_operational): Use GPG_ERR_NOT_OPERATIONAL.

* mpi/ec.c (_gcry_mpi_ec_get_mpi): Fix computation of Q.
(_gcry_mpi_ec_get_point): Ditto.
--

While checking the new code I figured that the auto-computation of Q
must have led to a segv.  It seems we had no test case for that.

Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 74 insertions, 0 deletions

diff --git a/cipher/ecc.c b/cipher/ecc.c
index fbd8c6a3..34ed2c38 100644
--- a/cipher/ecc.c
+++ b/cipher/ecc.c
@@ -66,6 +66,7 @@
 #include "cipher.h"
 #include "context.h"
 #include "ec-context.h"
+#include "pubkey-internal.h"
 
 /* Definition of a curve.  */
 typedef struct
@@ -1985,6 +1986,79 @@ _gcry_mpi_ec_new (gcry_ctx_t *r_ctx,
 }
 
 
+/* This is the wroker function for gcry_pubkey_get_sexp for ECC
+   algorithms.  Note that the caller has already stored NULL at
+   R_SEXP.  */
+gpg_err_code_t
+_gcry_pk_ecc_get_sexp (gcry_sexp_t *r_sexp, int mode, mpi_ec_t ec)
+{
+  gpg_err_code_t rc;
+  gcry_mpi_t mpi_G = NULL;
+  gcry_mpi_t mpi_Q = NULL;
+
+  if (!ec->p || !ec->a || !ec->b || !ec->G || !ec->n)
+    return GPG_ERR_BAD_CRYPT_CTX;
+
+  if (mode == GCRY_PK_GET_SECKEY && !ec->d)
+    return GPG_ERR_NO_SECKEY;
+
+  /* Compute the public point if it is missing.  */
+  if (!ec->Q && ec->d)
+    {
+      ec->Q = gcry_mpi_point_new (0);
+      _gcry_mpi_ec_mul_point (ec->Q, ec->d, ec->G, ec);
+    }
+
+  /* Encode G and Q.  */
+  mpi_G = _gcry_mpi_ec_ec2os (ec->G, ec);
+  if (!mpi_G)
+    {
+      rc = GPG_ERR_BROKEN_PUBKEY;
+      goto leave;
+    }
+  if (!ec->Q)
+    {
+      rc = GPG_ERR_BAD_CRYPT_CTX;
+      goto leave;
+    }
+  mpi_Q = _gcry_mpi_ec_ec2os (ec->Q, ec);
+  if (!mpi_Q)
+    {
+      rc = GPG_ERR_BROKEN_PUBKEY;
+      goto leave;
+    }
+
+  /* Fixme: We should return a curve name instead of the parameters if
+     if know that they match a curve.  */
+
+  if (ec->d && (!mode || mode == GCRY_PK_GET_SECKEY))
+    {
+      /* Let's return a private key. */
+      rc = gpg_err_code
+        (gcry_sexp_build
+         (r_sexp, NULL,
+          "(private-key(ecc(p%m)(a%m)(b%m)(g%m)(n%m)(q%m)(d%m)))",
+          ec->p, ec->a, ec->b, mpi_G, ec->n, mpi_Q, ec->d));
+    }
+  else if (ec->Q)
+    {
+      /* Let's return a public key.  */
+      rc = gpg_err_code
+        (gcry_sexp_build
+         (r_sexp, NULL,
+          "(public-key(ecc(p%m)(a%m)(b%m)(g%m)(n%m)(q%m)))",
+          ec->p, ec->a, ec->b, mpi_G, ec->n, mpi_Q));
+    }
+  else
+    rc = GPG_ERR_BAD_CRYPT_CTX;
+
+ leave:
+  mpi_free (mpi_Q);
+  mpi_free (mpi_G);
+  return rc;
+}
+
+
 
 /*
      Self-test section.