8 files changed, 55 insertions, 6 deletions

diff --git a/src/ecgen.c b/src/ecgen.c
index 3e5b145..4a7f94a 100644
--- a/src/ecgen.c
+++ b/src/ecgen.c
@@ -29,7 +29,6 @@
 #include "invalid/invalid.h"
 #include "io/input.h"
 #include "io/output.h"
-#include "misc/config.h"
 #include "util/timeout.h"
 
 const char *argp_program_version =
diff --git a/src/exhaustive/exhaustive.c b/src/exhaustive/exhaustive.c
index c6b54e9..fa748f5 100644
--- a/src/exhaustive/exhaustive.c
+++ b/src/exhaustive/exhaustive.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2017-2018 J08nY
  */
 #include "exhaustive.h"
+#include <misc/config.h>
 #include "anomalous.h"
 #include "ansi.h"
 #include "brainpool.h"
@@ -166,7 +167,11 @@ static void exhaustive_ginit(gen_f *generators) {
 		}
 	}
 	// setup common generators
-	generators[OFFSET_CURVE] = &curve_gen_any;
+	if (cfg->method == METHOD_TWIST) {
+		generators[OFFSET_CURVE] = &curve_gen_any_twist;
+	} else {
+		generators[OFFSET_CURVE] = &curve_gen_any;
+	}
 
 	switch (cfg->points.type) {
 		case POINTS_RANDOM:
diff --git a/src/gen/curve.c b/src/gen/curve.c
index 4996c28..f89044a 100644
--- a/src/gen/curve.c
+++ b/src/gen/curve.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2017-2018 J08nY
  */
 #include "curve.h"
+#include "math/twists.h"
 #include "point.h"
 #include "seed.h"
 #include "util/memory.h"
@@ -116,6 +117,16 @@ GENERATOR(curve_gen_any) {
 	}
 }
 
+GENERATOR(curve_gen_any_twist) {
+	int result = curve_gen_any(curve, args, state);
+	if (result != 1) {
+		return result;
+	} else {
+		twist_rand(curve);
+		return 1;
+	}
+}
+
 CHECK(curve_check_nonzero) {
 	if (gequal0(ell_get_disc(curve->curve))) {
 		return -3;
diff --git a/src/gen/curve.h b/src/gen/curve.h
index 8b82fa9..e2316c6 100644
--- a/src/gen/curve.h
+++ b/src/gen/curve.h
@@ -18,11 +18,22 @@
  *
  * @param curve A curve_t being generated
  * @param args unused
+ * @param state
  * @return state diff
  */
 GENERATOR(curve_gen_any);
 
 /**
+ * GENERATOR(gen_f)
+ *
+ * @param curve
+ * @param args
+ * @param state
+ * @return state diff
+ */
+GENERATOR(curve_gen_any_twist);
+
+/**
  * CHECK(check_f)
  * Checks that the curve has non-zero discriminant.
  *
diff --git a/src/io/cli.c b/src/io/cli.c
index efedb8b..46ef47a 100644
--- a/src/io/cli.c
+++ b/src/io/cli.c
@@ -41,7 +41,8 @@ enum opt_keys {
 	OPT_GPGEN,
 	OPT_GPCHECK,
 	OPT_HEXCHECK,
-	OPT_BRAINPOOL_RFC
+	OPT_BRAINPOOL_RFC,
+	OPT_TWIST,
 };
 
 // clang-format off
@@ -57,6 +58,7 @@ struct argp_option cli_options[] = {
 		{"brainpool",     OPT_BRAINPOOL,     "SEED", OPTION_ARG_OPTIONAL, "Generate a curve from SEED (Brainpool procedure).",                                     2},
 		{"brainpool-rfc", OPT_BRAINPOOL_RFC, "SEED", OPTION_ARG_OPTIONAL, "Generate a curve from SEED (Brainpool procedure, as per RFC 5639).",                    2},
 		{"invalid",       OPT_INVALID,       0,        0,                 "Generate a set of invalid curves, for a given curve (using Invalid curve algorithm).",  2},
+		{"twist",         OPT_TWIST,         0,        0,                 "Generate a twist of a given curve.",                                                    2},
 
 		{0,               0,                 0,        0,                 "Generation options:",                                                                   3},
 		{"random",        OPT_RANDOM,        0,        0,                 "Generate a random curve (using Random approach).",                                      3},
@@ -139,6 +141,7 @@ static void cli_end(struct argp_state *state) {
 		case METHOD_ANOMALOUS:
 		case METHOD_SEED:
 		case METHOD_INVALID:
+		case METHOD_TWIST:
 			break;
 		default:
 			printf("%u\n", cfg->method);
@@ -257,6 +260,9 @@ error_t cli_parse(int key, char *arg, struct argp_state *state) {
 				cfg->seed = arg;
 			}
 			break;
+		case OPT_TWIST:
+			cfg->method |= METHOD_TWIST;
+			break;
 
 		/* Generation options */
 		case OPT_COUNT:
diff --git a/src/math/twists.c b/src/math/twists.c
index 78481f4..3f1296d 100644
--- a/src/math/twists.c
+++ b/src/math/twists.c
@@ -3,8 +3,10 @@
  * Copyright (C) 2017-2018 J08nY
  */
 #include "twists.h"
+#include "gen/point.h"
+#include "gen/seed.h"
 
-void curve_twist_rand(curve_t *to, const curve_t *of) {
+void twist_rand_to(curve_t *to, const curve_t *of) {
 	to->field = gcopy(of->field);
 	GEN v = elltwist(of->curve, NULL);
 	to->curve = ellinit(v, to->field, -1);
@@ -15,4 +17,12 @@ void curve_twist_rand(curve_t *to, const curve_t *of) {
 		to->a = ell_get_a2(to->curve);
 		to->b = ell_get_a6(to->curve);
 	}
+}
+
+void twist_rand(curve_t *what) {
+	twist_rand_to(what, what);
+	seed_free(&what->seed);
+	what->order = NULL;
+	points_free_deep(&what->points, what->npoints);
+	points_free_deep(&what->generators, what->ngens);
 }
\ No newline at end of file
diff --git a/src/math/twists.h b/src/math/twists.h
index 3249047..dcbdb31 100644
--- a/src/math/twists.h
+++ b/src/math/twists.h
@@ -12,6 +12,12 @@
  * @param to The result of the twist.
  * @param of The curve to be twisted.
  */
-void curve_twist_rand(curve_t *to, const curve_t *of);
+void twist_rand_to(curve_t *to, const curve_t *of);
+
+/**
+ * @brief
+ * @param what
+ */
+void twist_rand(curve_t *what);
 
 #endif  // ECGEN_TWIST_H
diff --git a/src/misc/config.h b/src/misc/config.h
index de1c95e..367de52 100644
--- a/src/misc/config.h
+++ b/src/misc/config.h
@@ -33,7 +33,8 @@ typedef enum {
 	METHOD_CM = 1 << 0,
 	METHOD_ANOMALOUS = 1 << 1,
 	METHOD_SEED = 1 << 2,
-	METHOD_INVALID = 1 << 3
+	METHOD_INVALID = 1 << 3,
+	METHOD_TWIST
 } method_e;
 
 /**