--- /dev/null
+/*
+ * Elliptic-curve crypto module for PuTTY
+ * Implements the three required curves, no optional curves
+ * NOTE: Only curves on prime field are handled by the maths functions
+ */
+
+/*
+ * References:
+ *
+ * Elliptic curves in SSH are specified in RFC 5656:
+ * http://tools.ietf.org/html/rfc5656
+ *
+ * That specification delegates details of public key formatting and a
+ * lot of underlying mechanism to SEC 1:
+ * http://www.secg.org/sec1-v2.pdf
+ */
+
+#include <stdlib.h>
+#include <assert.h>
+
+#include "ssh.h"
+
+/* ----------------------------------------------------------------------
+ * Elliptic curve definitions
+ */
+
+static int initialise_curve(struct ec_curve *curve, int bits, unsigned char *p,
+ unsigned char *a, unsigned char *b,
+ unsigned char *n, unsigned char *Gx,
+ unsigned char *Gy)
+{
+ int length = bits / 8;
+ if (bits % 8) ++length;
+
+ curve->fieldBits = bits;
+ curve->p = bignum_from_bytes(p, length);
+ if (!curve->p) goto error;
+
+ /* Curve co-efficients */
+ curve->a = bignum_from_bytes(a, length);
+ if (!curve->a) goto error;
+ curve->b = bignum_from_bytes(b, length);
+ if (!curve->b) goto error;
+
+ /* Group order and generator */
+ curve->n = bignum_from_bytes(n, length);
+ if (!curve->n) goto error;
+ curve->G.x = bignum_from_bytes(Gx, length);
+ if (!curve->G.x) goto error;
+ curve->G.y = bignum_from_bytes(Gy, length);
+ if (!curve->G.y) goto error;
+ curve->G.curve = curve;
+ curve->G.infinity = 0;
+
+ return 1;
+ error:
+ if (curve->p) freebn(curve->p);
+ if (curve->a) freebn(curve->a);
+ if (curve->b) freebn(curve->b);
+ if (curve->n) freebn(curve->n);
+ if (curve->G.x) freebn(curve->G.x);
+ return 0;
+}
+
+unsigned char nistp256_oid[] = {0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07};
+int nistp256_oid_len = 8;
+unsigned char nistp384_oid[] = {0x2b, 0x81, 0x04, 0x00, 0x22};
+int nistp384_oid_len = 5;
+unsigned char nistp521_oid[] = {0x2b, 0x81, 0x04, 0x00, 0x23};
+int nistp521_oid_len = 5;
+
+struct ec_curve *ec_p256(void)
+{
+ static struct ec_curve curve = { 0 };
+ static unsigned char initialised = 0;
+
+ if (!initialised)
+ {
+ unsigned char p[] = {
+ 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x01,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+ };
+ unsigned char a[] = {
+ 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x01,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfc
+ };
+ unsigned char b[] = {
+ 0x5a, 0xc6, 0x35, 0xd8, 0xaa, 0x3a, 0x93, 0xe7,
+ 0xb3, 0xeb, 0xbd, 0x55, 0x76, 0x98, 0x86, 0xbc,
+ 0x65, 0x1d, 0x06, 0xb0, 0xcc, 0x53, 0xb0, 0xf6,
+ 0x3b, 0xce, 0x3c, 0x3e, 0x27, 0xd2, 0x60, 0x4b
+ };
+ unsigned char n[] = {
+ 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xbc, 0xe6, 0xfa, 0xad, 0xa7, 0x17, 0x9e, 0x84,
+ 0xf3, 0xb9, 0xca, 0xc2, 0xfc, 0x63, 0x25, 0x51
+ };
+ unsigned char Gx[] = {
+ 0x6b, 0x17, 0xd1, 0xf2, 0xe1, 0x2c, 0x42, 0x47,
+ 0xf8, 0xbc, 0xe6, 0xe5, 0x63, 0xa4, 0x40, 0xf2,
+ 0x77, 0x03, 0x7d, 0x81, 0x2d, 0xeb, 0x33, 0xa0,
+ 0xf4, 0xa1, 0x39, 0x45, 0xd8, 0x98, 0xc2, 0x96
+ };
+ unsigned char Gy[] = {
+ 0x4f, 0xe3, 0x42, 0xe2, 0xfe, 0x1a, 0x7f, 0x9b,
+ 0x8e, 0xe7, 0xeb, 0x4a, 0x7c, 0x0f, 0x9e, 0x16,
+ 0x2b, 0xce, 0x33, 0x57, 0x6b, 0x31, 0x5e, 0xce,
+ 0xcb, 0xb6, 0x40, 0x68, 0x37, 0xbf, 0x51, 0xf5
+ };
+
+ if (!initialise_curve(&curve, 256, p, a, b, n, Gx, Gy)) {
+ return NULL;
+ }
+
+ /* Now initialised, no need to do it again */
+ initialised = 1;
+ }
+
+ return &curve;
+}
+
+struct ec_curve *ec_p384(void)
+{
+ static struct ec_curve curve = { 0 };
+ static unsigned char initialised = 0;
+
+ if (!initialised)
+ {
+ unsigned char p[] = {
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe,
+ 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff
+ };
+ unsigned char a[] = {
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe,
+ 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xfc
+ };
+ unsigned char b[] = {
+ 0xb3, 0x31, 0x2f, 0xa7, 0xe2, 0x3e, 0xe7, 0xe4,
+ 0x98, 0x8e, 0x05, 0x6b, 0xe3, 0xf8, 0x2d, 0x19,
+ 0x18, 0x1d, 0x9c, 0x6e, 0xfe, 0x81, 0x41, 0x12,
+ 0x03, 0x14, 0x08, 0x8f, 0x50, 0x13, 0x87, 0x5a,
+ 0xc6, 0x56, 0x39, 0x8d, 0x8a, 0x2e, 0xd1, 0x9d,
+ 0x2a, 0x85, 0xc8, 0xed, 0xd3, 0xec, 0x2a, 0xef
+ };
+ unsigned char n[] = {
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xc7, 0x63, 0x4d, 0x81, 0xf4, 0x37, 0x2d, 0xdf,
+ 0x58, 0x1a, 0x0d, 0xb2, 0x48, 0xb0, 0xa7, 0x7a,
+ 0xec, 0xec, 0x19, 0x6a, 0xcc, 0xc5, 0x29, 0x73
+ };
+ unsigned char Gx[] = {
+ 0xaa, 0x87, 0xca, 0x22, 0xbe, 0x8b, 0x05, 0x37,
+ 0x8e, 0xb1, 0xc7, 0x1e, 0xf3, 0x20, 0xad, 0x74,
+ 0x6e, 0x1d, 0x3b, 0x62, 0x8b, 0xa7, 0x9b, 0x98,
+ 0x59, 0xf7, 0x41, 0xe0, 0x82, 0x54, 0x2a, 0x38,
+ 0x55, 0x02, 0xf2, 0x5d, 0xbf, 0x55, 0x29, 0x6c,
+ 0x3a, 0x54, 0x5e, 0x38, 0x72, 0x76, 0x0a, 0xb7
+ };
+ unsigned char Gy[] = {
+ 0x36, 0x17, 0xde, 0x4a, 0x96, 0x26, 0x2c, 0x6f,
+ 0x5d, 0x9e, 0x98, 0xbf, 0x92, 0x92, 0xdc, 0x29,
+ 0xf8, 0xf4, 0x1d, 0xbd, 0x28, 0x9a, 0x14, 0x7c,
+ 0xe9, 0xda, 0x31, 0x13, 0xb5, 0xf0, 0xb8, 0xc0,
+ 0x0a, 0x60, 0xb1, 0xce, 0x1d, 0x7e, 0x81, 0x9d,
+ 0x7a, 0x43, 0x1d, 0x7c, 0x90, 0xea, 0x0e, 0x5f
+ };
+
+ if (!initialise_curve(&curve, 384, p, a, b, n, Gx, Gy)) {
+ return NULL;
+ }
+
+ /* Now initialised, no need to do it again */
+ initialised = 1;
+ }
+
+ return &curve;
+}
+
+struct ec_curve *ec_p521(void)
+{
+ static struct ec_curve curve = { 0 };
+ static unsigned char initialised = 0;
+
+ if (!initialised)
+ {
+ unsigned char p[] = {
+ 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff
+ };
+ unsigned char a[] = {
+ 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xfc
+ };
+ unsigned char b[] = {
+ 0x00, 0x51, 0x95, 0x3e, 0xb9, 0x61, 0x8e, 0x1c,
+ 0x9a, 0x1f, 0x92, 0x9a, 0x21, 0xa0, 0xb6, 0x85,
+ 0x40, 0xee, 0xa2, 0xda, 0x72, 0x5b, 0x99, 0xb3,
+ 0x15, 0xf3, 0xb8, 0xb4, 0x89, 0x91, 0x8e, 0xf1,
+ 0x09, 0xe1, 0x56, 0x19, 0x39, 0x51, 0xec, 0x7e,
+ 0x93, 0x7b, 0x16, 0x52, 0xc0, 0xbd, 0x3b, 0xb1,
+ 0xbf, 0x07, 0x35, 0x73, 0xdf, 0x88, 0x3d, 0x2c,
+ 0x34, 0xf1, 0xef, 0x45, 0x1f, 0xd4, 0x6b, 0x50,
+ 0x3f, 0x00
+ };
+ unsigned char n[] = {
+ 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xfa, 0x51, 0x86, 0x87, 0x83, 0xbf, 0x2f,
+ 0x96, 0x6b, 0x7f, 0xcc, 0x01, 0x48, 0xf7, 0x09,
+ 0xa5, 0xd0, 0x3b, 0xb5, 0xc9, 0xb8, 0x89, 0x9c,
+ 0x47, 0xae, 0xbb, 0x6f, 0xb7, 0x1e, 0x91, 0x38,
+ 0x64, 0x09
+ };
+ unsigned char Gx[] = {
+ 0x00, 0xc6, 0x85, 0x8e, 0x06, 0xb7, 0x04, 0x04,
+ 0xe9, 0xcd, 0x9e, 0x3e, 0xcb, 0x66, 0x23, 0x95,
+ 0xb4, 0x42, 0x9c, 0x64, 0x81, 0x39, 0x05, 0x3f,
+ 0xb5, 0x21, 0xf8, 0x28, 0xaf, 0x60, 0x6b, 0x4d,
+ 0x3d, 0xba, 0xa1, 0x4b, 0x5e, 0x77, 0xef, 0xe7,
+ 0x59, 0x28, 0xfe, 0x1d, 0xc1, 0x27, 0xa2, 0xff,
+ 0xa8, 0xde, 0x33, 0x48, 0xb3, 0xc1, 0x85, 0x6a,
+ 0x42, 0x9b, 0xf9, 0x7e, 0x7e, 0x31, 0xc2, 0xe5,
+ 0xbd, 0x66
+ };
+ unsigned char Gy[] = {
+ 0x01, 0x18, 0x39, 0x29, 0x6a, 0x78, 0x9a, 0x3b,
+ 0xc0, 0x04, 0x5c, 0x8a, 0x5f, 0xb4, 0x2c, 0x7d,
+ 0x1b, 0xd9, 0x98, 0xf5, 0x44, 0x49, 0x57, 0x9b,
+ 0x44, 0x68, 0x17, 0xaf, 0xbd, 0x17, 0x27, 0x3e,
+ 0x66, 0x2c, 0x97, 0xee, 0x72, 0x99, 0x5e, 0xf4,
+ 0x26, 0x40, 0xc5, 0x50, 0xb9, 0x01, 0x3f, 0xad,
+ 0x07, 0x61, 0x35, 0x3c, 0x70, 0x86, 0xa2, 0x72,
+ 0xc2, 0x40, 0x88, 0xbe, 0x94, 0x76, 0x9f, 0xd1,
+ 0x66, 0x50
+ };
+
+ if (!initialise_curve(&curve, 521, p, a, b, n, Gx, Gy)) {
+ return NULL;
+ }
+
+ /* Now initialised, no need to do it again */
+ initialised = 1;
+ }
+
+ return &curve;
+}
+
+static struct ec_curve *ec_name_to_curve(char *name, int len) {
+ if (len == 8 && !memcmp(name, "nistp", 5)) {
+ name += 5;
+ if (!memcmp(name, "256", 3)) {
+ return ec_p256();
+ } else if (!memcmp(name, "384", 3)) {
+ return ec_p384();
+ } else if (!memcmp(name, "521", 3)) {
+ return ec_p521();
+ }
+ }
+
+ return NULL;
+}
+
+static int ec_curve_to_name(const struct ec_curve *curve, unsigned char *name, int len) {
+ /* Return length of string */
+ if (name == NULL) return 8;
+
+ /* Not enough space for the name */
+ if (len < 8) return 0;
+
+ /* Put the name in the buffer */
+ switch (curve->fieldBits) {
+ case 256:
+ memcpy(name+5, "256", 3);
+ break;
+ case 384:
+ memcpy(name+5, "384", 3);
+ break;
+ case 521:
+ memcpy(name+5, "521", 3);
+ break;
+ default:
+ return 0;
+ }
+
+ memcpy(name, "nistp", 5);
+ return 8;
+}
+
+/* Return 1 if a is -3 % p, otherwise return 0
+ * This is used because there are some maths optimisations */
+static int ec_aminus3(const struct ec_curve *curve)
+{
+ int ret;
+ Bignum _p;
+
+ _p = bignum_add_long(curve->a, 3);
+ if (!_p) return 0;
+
+ ret = !bignum_cmp(curve->p, _p);
+ freebn(_p);
+ return ret;
+}
+
+/* ----------------------------------------------------------------------
+ * Elliptic curve field maths
+ */
+
+static Bignum ecf_add(const Bignum a, const Bignum b,
+ const struct ec_curve *curve)
+{
+ Bignum a1, b1, ab, ret;
+
+ a1 = bigmod(a, curve->p);
+ if (!a1) return NULL;
+ b1 = bigmod(b, curve->p);
+ if (!b1)
+ {
+ freebn(a1);
+ return NULL;
+ }
+
+ ab = bigadd(a1, b1);
+ freebn(a1);
+ freebn(b1);
+ if (!ab) return NULL;
+
+ ret = bigmod(ab, curve->p);
+ freebn(ab);
+
+ return ret;
+}
+
+static Bignum ecf_square(const Bignum a, const struct ec_curve *curve)
+{
+ return modmul(a, a, curve->p);
+}
+
+static Bignum ecf_treble(const Bignum a, const struct ec_curve *curve)
+{
+ Bignum ret, tmp;
+
+ /* Double */
+ tmp = bignum_lshift(a, 1);
+ if (!tmp) return NULL;
+
+ /* Add itself (i.e. treble) */
+ ret = bigadd(tmp, a);
+ freebn(tmp);
+
+ /* Normalise */
+ while (ret != NULL && bignum_cmp(ret, curve->p) >= 0)
+ {
+ tmp = bigsub(ret, curve->p);
+ freebn(ret);
+ ret = tmp;
+ }
+
+ return ret;
+}
+
+static Bignum ecf_double(const Bignum a, const struct ec_curve *curve)
+{
+ Bignum ret = bignum_lshift(a, 1);
+ if (!ret) return NULL;
+ if (bignum_cmp(ret, curve->p) >= 0)
+ {
+ Bignum tmp = bigsub(ret, curve->p);
+ freebn(ret);
+ return tmp;
+ }
+ else
+ {
+ return ret;
+ }
+}
+
+/* ----------------------------------------------------------------------
+ * Memory functions
+ */
+
+void ec_point_free(struct ec_point *point)
+{
+ if (point == NULL) return;
+ point->curve = 0;
+ if (point->x) freebn(point->x);
+ if (point->y) freebn(point->y);
+ if (point->z) freebn(point->z);
+ point->infinity = 0;
+ sfree(point);
+}
+
+static struct ec_point *ec_point_new(const struct ec_curve *curve,
+ const Bignum x, const Bignum y, const Bignum z,
+ unsigned char infinity)
+{
+ struct ec_point *point = snewn(1, struct ec_point);
+ point->curve = curve;
+ point->x = x;
+ point->y = y;
+ point->z = z;
+ point->infinity = infinity ? 1 : 0;
+ return point;
+}
+
+static struct ec_point *ec_point_copy(const struct ec_point *a)
+{
+ if (a == NULL) return NULL;
+ return ec_point_new(a->curve,
+ a->x ? copybn(a->x) : NULL,
+ a->y ? copybn(a->y) : NULL,
+ a->z ? copybn(a->z) : NULL,
+ a->infinity);
+}
+
+static int ec_point_verify(const struct ec_point *a)
+{
+ if (a->infinity)
+ {
+ return 1;
+ }
+ else
+ {
+ /* Verify y^2 = x^3 + ax + b */
+ int ret = 0;
+
+ Bignum lhs = NULL, x3 = NULL, ax = NULL, x3ax = NULL, x3axm = NULL, x3axb = NULL, rhs = NULL;
+
+ Bignum Three = bignum_from_long(3);
+ if (!Three) return 0;
+
+ lhs = modmul(a->y, a->y, a->curve->p);
+ if (!lhs) goto error;
+
+ /* This uses montgomery multiplication to optimise */
+ x3 = modpow(a->x, Three, a->curve->p);
+ freebn(Three);
+ if (!x3) goto error;
+ ax = modmul(a->curve->a, a->x, a->curve->p);
+ if (!ax) goto error;
+ x3ax = bigadd(x3, ax);
+ if (!x3ax) goto error;
+ freebn(x3); x3 = NULL;
+ freebn(ax); ax = NULL;
+ x3axm = bigmod(x3ax, a->curve->p);
+ if (!x3axm) goto error;
+ freebn(x3ax); x3ax = NULL;
+ x3axb = bigadd(x3axm, a->curve->b);
+ if (!x3axb) goto error;
+ freebn(x3axm); x3axm = NULL;
+ rhs = bigmod(x3axb, a->curve->p);
+ if (!rhs) goto error;
+ freebn(x3axb);
+
+ ret = bignum_cmp(lhs, rhs) ? 0 : 1;
+ freebn(lhs);
+ freebn(rhs);
+
+ return ret;
+
+ error:
+ if (x3) freebn(x3);
+ if (ax) freebn(ax);
+ if (x3ax) freebn(x3ax);
+ if (x3axm) freebn(x3axm);
+ if (x3axb) freebn(x3axb);
+ if (lhs) freebn(lhs);
+ return 0;
+ }
+}
+
+/* ----------------------------------------------------------------------
+ * Elliptic curve point maths
+ */
+
+/* Returns 1 on success and 0 on memory error */
+static int ecp_normalise(struct ec_point *a)
+{
+ Bignum Z2, Z2inv, Z3, Z3inv, tx, ty;
+
+ /* In Jacobian Coordinates the triple (X, Y, Z) represents
+ the affine point (X / Z^2, Y / Z^3) */
+ if (!a) {
+ // No point
+ return 0;
+ }
+ if (a->infinity) {
+ // Point is at infinity - i.e. normalised
+ return 1;
+ } else if (!a->x || !a->y) {
+ // No point defined
+ return 0;
+ } else if (!a->z) {
+ // Already normalised
+ return 1;
+ }
+
+ Z2 = ecf_square(a->z, a->curve);
+ if (!Z2) {
+ return 0;
+ }
+ Z2inv = modinv(Z2, a->curve->p);
+ if (!Z2inv) {
+ freebn(Z2);
+ return 0;
+ }
+ tx = modmul(a->x, Z2inv, a->curve->p);
+ freebn(Z2inv);
+ if (!tx) {
+ freebn(Z2);
+ return 0;
+ }
+
+ Z3 = modmul(Z2, a->z, a->curve->p);
+ freebn(Z2);
+ if (!Z3) {
+ freebn(tx);
+ return 0;
+ }
+ Z3inv = modinv(Z3, a->curve->p);
+ freebn(Z3);
+ if (!Z3inv) {
+ freebn(tx);
+ return 0;
+ }
+ ty = modmul(a->y, Z3inv, a->curve->p);
+ freebn(Z3inv);
+ if (!ty) {
+ freebn(tx);
+ return 0;
+ }
+
+ freebn(a->x);
+ a->x = tx;
+ freebn(a->y);
+ a->y = ty;
+ freebn(a->z);
+ a->z = NULL;
+ return 1;
+}
+
+static struct ec_point *ecp_double(const struct ec_point *a, const int aminus3)
+{
+ Bignum S, M, outx, outy, outz;
+
+ if (a->infinity || bignum_cmp(a->y, Zero) == 0)
+ {
+ /* Identity */
+ return ec_point_new(a->curve, NULL, NULL, NULL, 1);
+ }
+
+ /* S = 4*X*Y^2 */
+ {
+ Bignum Y2, XY2, _2XY2;
+
+ Y2 = ecf_square(a->y, a->curve);
+ if (!Y2) {
+ return NULL;
+ }
+ XY2 = modmul(a->x, Y2, a->curve->p);
+ freebn(Y2);
+ if (!XY2) {
+ return NULL;
+ }
+
+ _2XY2 = ecf_double(XY2, a->curve);
+ freebn(XY2);
+ if (!_2XY2) {
+ return NULL;
+ }
+ S = ecf_double(_2XY2, a->curve);
+ freebn(_2XY2);
+ if (!S) {
+ return NULL;
+ }
+ }
+
+ /* Faster calculation if a = -3 */
+ if (aminus3) {
+ /* if a = -3, then M can also be calculated as M = 3*(X + Z^2)*(X - Z^2) */
+ Bignum Z2, XpZ2, XmZ2, second;
+
+ if (a->z == NULL) {
+ Z2 = copybn(One);
+ } else {
+ Z2 = ecf_square(a->z, a->curve);
+ }
+ if (!Z2) {
+ freebn(S);
+ return NULL;
+ }
+
+ XpZ2 = ecf_add(a->x, Z2, a->curve);
+ if (!XpZ2) {
+ freebn(S);
+ freebn(Z2);
+ return NULL;
+ }
+ XmZ2 = modsub(a->x, Z2, a->curve->p);
+ freebn(Z2);
+ if (!XpZ2) {
+ freebn(S);
+ freebn(XpZ2);
+ return NULL;
+ }
+
+ second = modmul(XpZ2, XmZ2, a->curve->p);
+ freebn(XpZ2);
+ freebn(XmZ2);
+ if (!second) {
+ freebn(S);
+ return NULL;
+ }
+
+ M = ecf_treble(second, a->curve);
+ freebn(second);
+ if (!M) {
+ freebn(S);
+ return NULL;
+ }
+ } else {
+ /* M = 3*X^2 + a*Z^4 */
+ Bignum _3X2, X2, aZ4;
+
+ if (a->z == NULL) {
+ aZ4 = copybn(a->curve->a);
+ } else {
+ Bignum Z2, Z4;
+
+ Z2 = ecf_square(a->z, a->curve);
+ if (!Z2) {
+ freebn(S);
+ return NULL;
+ }
+ Z4 = ecf_square(Z2, a->curve);
+ freebn(Z2);
+ if (!Z4) {
+ freebn(S);
+ return NULL;
+ }
+ aZ4 = modmul(a->curve->a, Z4, a->curve->p);
+ freebn(Z4);
+ }
+ if (!aZ4) {
+ freebn(S);
+ return NULL;
+ }
+
+ X2 = modmul(a->x, a->x, a->curve->p);
+ if (!X2) {
+ freebn(S);
+ freebn(aZ4);
+ return NULL;
+ }
+ _3X2 = ecf_treble(X2, a->curve);
+ freebn(X2);
+ if (!_3X2) {
+ freebn(S);
+ freebn(aZ4);
+ return NULL;
+ }
+ M = ecf_add(_3X2, aZ4, a->curve);
+ freebn(_3X2);
+ freebn(aZ4);
+ if (!M) {
+ freebn(S);
+ return NULL;
+ }
+ }
+
+ /* X' = M^2 - 2*S */
+ {
+ Bignum M2, _2S;
+
+ M2 = ecf_square(M, a->curve);
+ if (!M2) {
+ freebn(S);
+ freebn(M);
+ return NULL;
+ }
+
+ _2S = ecf_double(S, a->curve);
+ if (!_2S) {
+ freebn(M2);
+ freebn(S);
+ freebn(M);
+ return NULL;
+ }
+
+ outx = modsub(M2, _2S, a->curve->p);
+ freebn(M2);
+ freebn(_2S);
+ if (!outx) {
+ freebn(S);
+ freebn(M);
+ return NULL;
+ }
+ }
+
+ /* Y' = M*(S - X') - 8*Y^4 */
+ {
+ Bignum SX, MSX, Eight, Y2, Y4, _8Y4;
+
+ SX = modsub(S, outx, a->curve->p);
+ freebn(S);
+ if (!SX) {
+ freebn(M);
+ freebn(outx);
+ return NULL;
+ }
+ MSX = modmul(M, SX, a->curve->p);
+ freebn(SX);
+ freebn(M);
+ if (!MSX) {
+ freebn(outx);
+ return NULL;
+ }
+ Y2 = ecf_square(a->y, a->curve);
+ if (!Y2) {
+ freebn(outx);
+ freebn(MSX);
+ return NULL;
+ }
+ Y4 = ecf_square(Y2, a->curve);
+ freebn(Y2);
+ if (!Y4) {
+ freebn(outx);
+ freebn(MSX);
+ return NULL;
+ }
+ Eight = bignum_from_long(8);
+ if (!Eight) {
+ freebn(outx);
+ freebn(MSX);
+ freebn(Y4);
+ return NULL;
+ }
+ _8Y4 = modmul(Eight, Y4, a->curve->p);
+ freebn(Eight);
+ freebn(Y4);
+ if (!_8Y4) {
+ freebn(outx);
+ freebn(MSX);
+ return NULL;
+ }
+ outy = modsub(MSX, _8Y4, a->curve->p);
+ freebn(MSX);
+ freebn(_8Y4);
+ if (!outy) {
+ freebn(outx);
+ return NULL;
+ }
+ }
+
+ /* Z' = 2*Y*Z */
+ {
+ Bignum YZ;
+
+ if (a->z == NULL) {
+ YZ = copybn(a->y);
+ } else {
+ YZ = modmul(a->y, a->z, a->curve->p);
+ }
+ if (!YZ) {
+ freebn(outx);
+ freebn(outy);
+ return NULL;
+ }
+
+ outz = ecf_double(YZ, a->curve);
+ freebn(YZ);
+ if (!outz) {
+ freebn(outx);
+ freebn(outy);
+ return NULL;
+ }
+ }
+
+ return ec_point_new(a->curve, outx, outy, outz, 0);
+}
+
+static struct ec_point *ecp_add(const struct ec_point *a,
+ const struct ec_point *b,
+ const int aminus3)
+{
+ Bignum U1, U2, S1, S2, outx, outy, outz;
+
+ /* Check if multiplying by infinity */
+ if (a->infinity) return ec_point_copy(b);
+ if (b->infinity) return ec_point_copy(a);
+
+ /* U1 = X1*Z2^2 */
+ /* S1 = Y1*Z2^3 */
+ if (b->z) {
+ Bignum Z2, Z3;
+
+ Z2 = ecf_square(b->z, a->curve);
+ if (!Z2) {
+ return NULL;
+ }
+ U1 = modmul(a->x, Z2, a->curve->p);
+ if (!U1) {
+ freebn(Z2);
+ return NULL;
+ }
+ Z3 = modmul(Z2, b->z, a->curve->p);
+ freebn(Z2);
+ if (!Z3) {
+ freebn(U1);
+ return NULL;
+ }
+ S1 = modmul(a->y, Z3, a->curve->p);
+ freebn(Z3);
+ if (!S1) {
+ freebn(U1);
+ return NULL;
+ }
+ } else {
+ U1 = copybn(a->x);
+ if (!U1) {
+ return NULL;
+ }
+ S1 = copybn(a->y);
+ if (!S1) {
+ freebn(U1);
+ return NULL;
+ }
+ }
+
+ /* U2 = X2*Z1^2 */
+ /* S2 = Y2*Z1^3 */
+ if (a->z) {
+ Bignum Z2, Z3;
+
+ Z2 = ecf_square(a->z, b->curve);
+ if (!Z2) {
+ freebn(U1);
+ freebn(S1);
+ return NULL;
+ }
+ U2 = modmul(b->x, Z2, b->curve->p);
+ if (!U2) {
+ freebn(U1);
+ freebn(S1);
+ freebn(Z2);
+ return NULL;
+ }
+ Z3 = modmul(Z2, a->z, b->curve->p);
+ freebn(Z2);
+ if (!Z3) {
+ freebn(U1);
+ freebn(S1);
+ freebn(U2);
+ return NULL;
+ }
+ S2 = modmul(b->y, Z3, b->curve->p);
+ freebn(Z3);
+ if (!S2) {
+ freebn(U1);
+ freebn(S1);
+ freebn(U2);
+ return NULL;
+ }
+ } else {
+ U2 = copybn(b->x);
+ if (!U2) {
+ freebn(U1);
+ freebn(S1);
+ return NULL;
+ }
+ S2 = copybn(b->y);
+ if (!S2) {
+ freebn(U1);
+ freebn(S1);
+ freebn(U2);
+ return NULL;
+ }
+ }
+
+ /* Check if multiplying by self */
+ if (bignum_cmp(U1, U2) == 0)
+ {
+ freebn(U1);
+ freebn(U2);
+ if (bignum_cmp(S1, S2) == 0)
+ {
+ freebn(S1);
+ freebn(S2);
+ return ecp_double(a, aminus3);
+ }
+ else
+ {
+ freebn(S1);
+ freebn(S2);
+ /* Infinity */
+ return ec_point_new(a->curve, NULL, NULL, NULL, 1);
+ }
+ }
+
+ {
+ Bignum H, R, UH2, H3;
+
+ /* H = U2 - U1 */
+ H = modsub(U2, U1, a->curve->p);
+ freebn(U2);
+ if (!H) {
+ freebn(U1);
+ freebn(S1);
+ freebn(S2);
+ return NULL;
+ }
+
+ /* R = S2 - S1 */
+ R = modsub(S2, S1, a->curve->p);
+ freebn(S2);
+ if (!R) {
+ freebn(H);
+ freebn(S1);
+ freebn(U1);
+ return NULL;
+ }
+
+ /* X3 = R^2 - H^3 - 2*U1*H^2 */
+ {
+ Bignum R2, H2, _2UH2, first;
+
+ H2 = ecf_square(H, a->curve);
+ if (!H2) {
+ freebn(U1);
+ freebn(S1);
+ freebn(H);
+ freebn(R);
+ return NULL;
+ }
+ UH2 = modmul(U1, H2, a->curve->p);
+ freebn(U1);
+ if (!UH2) {
+ freebn(H2);
+ freebn(S1);
+ freebn(H);
+ freebn(R);
+ return NULL;
+ }
+ H3 = modmul(H2, H, a->curve->p);
+ freebn(H2);
+ if (!H3) {
+ freebn(UH2);
+ freebn(S1);
+ freebn(H);
+ freebn(R);
+ return NULL;
+ }
+ R2 = ecf_square(R, a->curve);
+ if (!R2) {
+ freebn(H3);
+ freebn(UH2);
+ freebn(S1);
+ freebn(H);
+ freebn(R);
+ return NULL;
+ }
+ _2UH2 = ecf_double(UH2, a->curve);
+ if (!_2UH2) {
+ freebn(R2);
+ freebn(H3);
+ freebn(UH2);
+ freebn(S1);
+ freebn(H);
+ freebn(R);
+ return NULL;
+ }
+ first = modsub(R2, H3, a->curve->p);
+ freebn(R2);
+ if (!first) {
+ freebn(H3);
+ freebn(_2UH2);
+ freebn(UH2);
+ freebn(S1);
+ freebn(H);
+ freebn(R);
+ return NULL;
+ }
+ outx = modsub(first, _2UH2, a->curve->p);
+ freebn(first);
+ freebn(_2UH2);
+ if (!outx) {
+ freebn(H3);
+ freebn(UH2);
+ freebn(S1);
+ freebn(H);
+ freebn(R);
+ return NULL;
+ }
+ }
+
+ /* Y3 = R*(U1*H^2 - X3) - S1*H^3 */
+ {
+ Bignum RUH2mX, UH2mX, SH3;
+
+ UH2mX = modsub(UH2, outx, a->curve->p);
+ freebn(UH2);
+ if (!UH2mX) {
+ freebn(outx);
+ freebn(H3);
+ freebn(S1);
+ freebn(H);
+ freebn(R);
+ return NULL;
+ }
+ RUH2mX = modmul(R, UH2mX, a->curve->p);
+ freebn(UH2mX);
+ freebn(R);
+ if (!RUH2mX) {
+ freebn(outx);
+ freebn(H3);
+ freebn(S1);
+ freebn(H);
+ return NULL;
+ }
+ SH3 = modmul(S1, H3, a->curve->p);
+ freebn(S1);
+ freebn(H3);
+ if (!SH3) {
+ freebn(RUH2mX);
+ freebn(outx);
+ freebn(H);
+ return NULL;
+ }
+
+ outy = modsub(RUH2mX, SH3, a->curve->p);
+ freebn(RUH2mX);
+ freebn(SH3);
+ if (!outy) {
+ freebn(outx);
+ freebn(H);
+ return NULL;
+ }
+ }
+
+ /* Z3 = H*Z1*Z2 */
+ if (a->z && b->z) {
+ Bignum ZZ;
+
+ ZZ = modmul(a->z, b->z, a->curve->p);
+ if (!ZZ) {
+ freebn(outx);
+ freebn(outy);
+ freebn(H);
+ return NULL;
+ }
+ outz = modmul(H, ZZ, a->curve->p);
+ freebn(H);
+ freebn(ZZ);
+ if (!outz) {
+ freebn(outx);
+ freebn(outy);
+ return NULL;
+ }
+ } else if (a->z) {
+ outz = modmul(H, a->z, a->curve->p);
+ freebn(H);
+ if (!outz) {
+ freebn(outx);
+ freebn(outy);
+ return NULL;
+ }
+ } else if (b->z) {
+ outz = modmul(H, b->z, a->curve->p);
+ freebn(H);
+ if (!outz) {
+ freebn(outx);
+ freebn(outy);
+ return NULL;
+ }
+ } else {
+ outz = H;
+ }
+ }
+
+ return ec_point_new(a->curve, outx, outy, outz, 0);
+}
+
+static struct ec_point *ecp_mul_(const struct ec_point *a, const Bignum b, int aminus3)
+{
+ struct ec_point *A, *ret;
+ int bits, i;
+
+ A = ec_point_copy(a);
+ ret = ec_point_new(a->curve, NULL, NULL, NULL, 1);
+
+ bits = bignum_bitcount(b);
+ for (i = 0; ret != NULL && A != NULL && i < bits; ++i)
+ {
+ if (bignum_bit(b, i))
+ {
+ struct ec_point *tmp = ecp_add(ret, A, aminus3);
+ ec_point_free(ret);
+ ret = tmp;
+ }
+ if (i+1 != bits)
+ {
+ struct ec_point *tmp = ecp_double(A, aminus3);
+ ec_point_free(A);
+ A = tmp;
+ }
+ }
+
+ if (!A) {
+ ec_point_free(ret);
+ ret = NULL;
+ } else {
+ ec_point_free(A);
+ }
+
+ return ret;
+}
+
+/* Not static because it is used by sshecdsag.c to generate a new key */
+struct ec_point *ecp_mul(const struct ec_point *a, const Bignum b)
+{
+ struct ec_point *ret = ecp_mul_(a, b, ec_aminus3(a->curve));
+
+ if (!ecp_normalise(ret)) {
+ ec_point_free(ret);
+ return NULL;
+ }
+
+ return ret;
+}
+
+static struct ec_point *ecp_summul(const Bignum a, const Bignum b,
+ const struct ec_point *point)
+{
+ struct ec_point *aG, *bP, *ret;
+ int aminus3 = ec_aminus3(point->curve);
+
+ aG = ecp_mul_(&point->curve->G, a, aminus3);
+ if (!aG) return NULL;
+ bP = ecp_mul_(point, b, aminus3);
+ if (!bP) {
+ ec_point_free(aG);
+ return NULL;
+ }
+
+ ret = ecp_add(aG, bP, aminus3);
+
+ ec_point_free(aG);
+ ec_point_free(bP);
+
+ if (!ecp_normalise(ret)) {
+ ec_point_free(ret);
+ return NULL;
+ }
+
+ return ret;
+}
+
+/* ----------------------------------------------------------------------
+ * Basic sign and verify routines
+ */
+
+static int _ecdsa_verify(const struct ec_point *publicKey,
+ const unsigned char *data, const int dataLen,
+ const Bignum r, const Bignum s)
+{
+ int z_bits, n_bits;
+ Bignum z;
+ int valid = 0;
+
+ /* Sanity checks */
+ if (bignum_cmp(r, Zero) == 0 || bignum_cmp(r, publicKey->curve->n) >= 0
+ || bignum_cmp(s, Zero) == 0 || bignum_cmp(s, publicKey->curve->n) >= 0)
+ {
+ return 0;
+ }
+
+ /* z = left most bitlen(curve->n) of data */
+ z = bignum_from_bytes(data, dataLen);
+ if (!z) return 0;
+ n_bits = bignum_bitcount(publicKey->curve->n);
+ z_bits = bignum_bitcount(z);
+ if (z_bits > n_bits)
+ {
+ Bignum tmp = bignum_rshift(z, z_bits - n_bits);
+ freebn(z);
+ z = tmp;
+ if (!z) return 0;
+ }
+
+ /* Ensure z in range of n */
+ {
+ Bignum tmp = bigmod(z, publicKey->curve->n);
+ freebn(z);
+ z = tmp;
+ if (!z) return 0;
+ }
+
+ /* Calculate signature */
+ {
+ Bignum w, x, u1, u2;
+ struct ec_point *tmp;
+
+ w = modinv(s, publicKey->curve->n);
+ if (!w) {
+ freebn(z);
+ return 0;
+ }
+ u1 = modmul(z, w, publicKey->curve->n);
+ if (!u1) {
+ freebn(z);
+ freebn(w);
+ return 0;
+ }
+ u2 = modmul(r, w, publicKey->curve->n);
+ freebn(w);
+ if (!u2) {
+ freebn(z);
+ freebn(u1);
+ return 0;
+ }
+
+ tmp = ecp_summul(u1, u2, publicKey);
+ freebn(u1);
+ freebn(u2);
+ if (!tmp) {
+ freebn(z);
+ return 0;
+ }
+
+ x = bigmod(tmp->x, publicKey->curve->n);
+ ec_point_free(tmp);
+ if (!x) {
+ freebn(z);
+ return 0;
+ }
+
+ valid = (bignum_cmp(r, x) == 0) ? 1 : 0;
+ freebn(x);
+ }
+
+ freebn(z);
+
+ return valid;
+}
+
+static void _ecdsa_sign(const Bignum privateKey, const struct ec_curve *curve,
+ const unsigned char *data, const int dataLen,
+ Bignum *r, Bignum *s)
+{
+ unsigned char digest[20];
+ int z_bits, n_bits;
+ Bignum z, k;
+ struct ec_point *kG;
+
+ *r = NULL;
+ *s = NULL;
+
+ /* z = left most bitlen(curve->n) of data */
+ z = bignum_from_bytes(data, dataLen);
+ if (!z) return;
+ n_bits = bignum_bitcount(curve->n);
+ z_bits = bignum_bitcount(z);
+ if (z_bits > n_bits)
+ {
+ Bignum tmp;
+ tmp = bignum_rshift(z, z_bits - n_bits);
+ freebn(z);
+ z = tmp;
+ if (!z) return;
+ }
+
+ /* Generate k between 1 and curve->n, using the same deterministic
+ * k generation system we use for conventional DSA. */
+ SHA_Simple(data, dataLen, digest);
+ k = dss_gen_k("ECDSA deterministic k generator", curve->n, privateKey,
+ digest, sizeof(digest));
+ if (!k) return;
+
+ kG = ecp_mul(&curve->G, k);
+ if (!kG) {
+ freebn(z);
+ freebn(k);
+ return;
+ }
+
+ /* r = kG.x mod n */
+ *r = bigmod(kG->x, curve->n);
+ ec_point_free(kG);
+ if (!*r) {
+ freebn(z);
+ freebn(k);
+ return;
+ }
+
+ /* s = (z + r * priv)/k mod n */
+ {
+ Bignum rPriv, zMod, first, firstMod, kInv;
+ rPriv = modmul(*r, privateKey, curve->n);
+ if (!rPriv) {
+ freebn(*r);
+ freebn(z);
+ freebn(k);
+ return;
+ }
+ zMod = bigmod(z, curve->n);
+ freebn(z);
+ if (!zMod) {
+ freebn(rPriv);
+ freebn(*r);
+ freebn(k);
+ return;
+ }
+ first = bigadd(rPriv, zMod);
+ freebn(rPriv);
+ freebn(zMod);
+ if (!first) {
+ freebn(*r);
+ freebn(k);
+ return;
+ }
+ firstMod = bigmod(first, curve->n);
+ freebn(first);
+ if (!firstMod) {
+ freebn(*r);
+ freebn(k);
+ return;
+ }
+ kInv = modinv(k, curve->n);
+ freebn(k);
+ if (!kInv) {
+ freebn(firstMod);
+ freebn(*r);
+ return;
+ }
+ *s = modmul(firstMod, kInv, curve->n);
+ freebn(firstMod);
+ freebn(kInv);
+ if (!*s) {
+ freebn(*r);
+ return;
+ }
+ }
+}
+
+/* ----------------------------------------------------------------------
+ * Misc functions
+ */
+
+static void getstring(char **data, int *datalen, char **p, int *length)
+{
+ *p = NULL;
+ if (*datalen < 4)
+ return;
+ *length = toint(GET_32BIT(*data));
+ if (*length < 0)
+ return;
+ *datalen -= 4;
+ *data += 4;
+ if (*datalen < *length)
+ return;
+ *p = *data;
+ *data += *length;
+ *datalen -= *length;
+}
+
+static Bignum getmp(char **data, int *datalen)
+{
+ char *p;
+ int length;
+
+ getstring(data, datalen, &p, &length);
+ if (!p)
+ return NULL;
+ if (p[0] & 0x80)
+ return NULL; /* negative mp */
+ return bignum_from_bytes((unsigned char *)p, length);
+}
+
+static int decodepoint(char *p, int length, struct ec_point *point)
+{
+ if (length < 1 || p[0] != 0x04) /* Only support uncompressed point */
+ return 0;
+ /* Skip compression flag */
+ ++p;
+ --length;
+ /* The two values must be equal length */
+ if (length % 2 != 0) {
+ point->x = NULL;
+ point->y = NULL;
+ point->z = NULL;
+ return 0;
+ }
+ length = length / 2;
+ point->x = bignum_from_bytes((unsigned char *)p, length);
+ if (!point->x) return 0;
+ p += length;
+ point->y = bignum_from_bytes((unsigned char *)p, length);
+ if (!point->y) {
+ freebn(point->x);
+ point->x = NULL;
+ return 0;
+ }
+ point->z = NULL;
+
+ /* Verify the point is on the curve */
+ if (!ec_point_verify(point)) {
+ ec_point_free(point);
+ return 0;
+ }
+
+ return 1;
+}
+
+static int getmppoint(char **data, int *datalen, struct ec_point *point)
+{
+ char *p;
+ int length;
+
+ getstring(data, datalen, &p, &length);
+ if (!p) return 0;
+ return decodepoint(p, length, point);
+}
+
+/* ----------------------------------------------------------------------
+ * Exposed ECDSA interface
+ */
+
+static void ecdsa_freekey(void *key)
+{
+ struct ec_key *ec = (struct ec_key *) key;
+ if (!ec) return;
+
+ if (ec->publicKey.x)
+ freebn(ec->publicKey.x);
+ if (ec->publicKey.y)
+ freebn(ec->publicKey.y);
+ if (ec->publicKey.z)
+ freebn(ec->publicKey.z);
+ if (ec->privateKey)
+ freebn(ec->privateKey);
+ sfree(ec);
+}
+
+static void *ecdsa_newkey(char *data, int len)
+{
+ char *p;
+ int slen;
+ struct ec_key *ec;
+ struct ec_curve *curve;
+
+ getstring(&data, &len, &p, &slen);
+
+ if (!p || slen < 11 || memcmp(p, "ecdsa-sha2-", 11)) {
+ return NULL;
+ }
+ curve = ec_name_to_curve(p+11, slen-11);
+ if (!curve) return NULL;
+
+ getstring(&data, &len, &p, &slen);
+
+ if (curve != ec_name_to_curve(p, slen)) return NULL;
+
+ ec = snew(struct ec_key);
+
+ ec->publicKey.curve = curve;
+ ec->publicKey.infinity = 0;
+ ec->publicKey.x = NULL;
+ ec->publicKey.y = NULL;
+ ec->publicKey.z = NULL;
+ if (!getmppoint(&data, &len, &ec->publicKey)) {
+ ecdsa_freekey(ec);
+ return NULL;
+ }
+ ec->privateKey = NULL;
+
+ if (!ec->publicKey.x || !ec->publicKey.y ||
+ bignum_cmp(ec->publicKey.x, curve->p) >= 0 ||
+ bignum_cmp(ec->publicKey.y, curve->p) >= 0)
+ {
+ ecdsa_freekey(ec);
+ ec = NULL;
+ }
+
+ return ec;
+}
+
+static char *ecdsa_fmtkey(void *key)
+{
+ struct ec_key *ec = (struct ec_key *) key;
+ char *p;
+ int len, i, pos, nibbles;
+ static const char hex[] = "0123456789abcdef";
+ if (!ec->publicKey.x || !ec->publicKey.y || !ec->publicKey.curve)
+ return NULL;
+
+ pos = ec_curve_to_name(ec->publicKey.curve, NULL, 0);
+ if (pos == 0) return NULL;
+
+ len = 4 + 2 + 1; /* 2 x "0x", punctuation, \0 */
+ len += pos; /* Curve name */
+ len += 4 * (bignum_bitcount(ec->publicKey.x) + 15) / 16;
+ len += 4 * (bignum_bitcount(ec->publicKey.y) + 15) / 16;
+ p = snewn(len, char);
+
+ pos = ec_curve_to_name(ec->publicKey.curve, (unsigned char*)p, pos);
+ pos += sprintf(p + pos, ",0x");
+ nibbles = (3 + bignum_bitcount(ec->publicKey.x)) / 4;
+ if (nibbles < 1)
+ nibbles = 1;
+ for (i = nibbles; i--;) {
+ p[pos++] =
+ hex[(bignum_byte(ec->publicKey.x, i / 2) >> (4 * (i % 2))) & 0xF];
+ }
+ pos += sprintf(p + pos, ",0x");
+ nibbles = (3 + bignum_bitcount(ec->publicKey.y)) / 4;
+ if (nibbles < 1)
+ nibbles = 1;
+ for (i = nibbles; i--;) {
+ p[pos++] =
+ hex[(bignum_byte(ec->publicKey.y, i / 2) >> (4 * (i % 2))) & 0xF];
+ }
+ p[pos] = '\0';
+ return p;
+}
+
+static unsigned char *ecdsa_public_blob(void *key, int *len)
+{
+ struct ec_key *ec = (struct ec_key *) key;
+ int pointlen, bloblen, namelen;
+ int i;
+ unsigned char *blob, *p;
+
+ namelen = ec_curve_to_name(ec->publicKey.curve, NULL, 0);
+ if (namelen == 0) return NULL;
+
+ pointlen = (bignum_bitcount(ec->publicKey.curve->p) + 7) / 8;
+
+ /*
+ * string "ecdsa-sha2-<name>", string "<name>", 0x04 point x, y.
+ */
+ bloblen = 4 + 11 + namelen + 4 + namelen + 4 + 1 + (pointlen * 2);
+ blob = snewn(bloblen, unsigned char);
+
+ p = blob;
+ PUT_32BIT(p, 11 + namelen);
+ p += 4;
+ memcpy(p, "ecdsa-sha2-", 11);
+ p += 11;
+ p += ec_curve_to_name(ec->publicKey.curve, p, namelen);
+ PUT_32BIT(p, namelen);
+ p += 4;
+ p += ec_curve_to_name(ec->publicKey.curve, p, namelen);
+ PUT_32BIT(p, (2 * pointlen) + 1);
+ p += 4;
+ *p++ = 0x04;
+ for (i = pointlen; i--;)
+ *p++ = bignum_byte(ec->publicKey.x, i);
+ for (i = pointlen; i--;)
+ *p++ = bignum_byte(ec->publicKey.y, i);
+
+ assert(p == blob + bloblen);
+ *len = bloblen;
+
+ return blob;
+}
+
+static unsigned char *ecdsa_private_blob(void *key, int *len)
+{
+ struct ec_key *ec = (struct ec_key *) key;
+ int keylen, bloblen;
+ int i;
+ unsigned char *blob, *p;
+
+ if (!ec->privateKey) return NULL;
+
+ keylen = (bignum_bitcount(ec->privateKey) + 8) / 8;
+
+ /*
+ * mpint privateKey. Total 4 + keylen.
+ */
+ bloblen = 4 + keylen;
+ blob = snewn(bloblen, unsigned char);
+
+ p = blob;
+ PUT_32BIT(p, keylen);
+ p += 4;
+ for (i = keylen; i--;)
+ *p++ = bignum_byte(ec->privateKey, i);
+
+ assert(p == blob + bloblen);
+ *len = bloblen;
+ return blob;
+}
+
+static void *ecdsa_createkey(unsigned char *pub_blob, int pub_len,
+ unsigned char *priv_blob, int priv_len)
+{
+ struct ec_key *ec;
+ struct ec_point *publicKey;
+ char *pb = (char *) priv_blob;
+
+ ec = (struct ec_key*)ecdsa_newkey((char *) pub_blob, pub_len);
+ if (!ec) {
+ return NULL;
+ }
+
+ ec->privateKey = getmp(&pb, &priv_len);
+ if (!ec->privateKey) {
+ ecdsa_freekey(ec);
+ return NULL;
+ }
+
+ /* Check that private key generates public key */
+ publicKey = ecp_mul(&ec->publicKey.curve->G, ec->privateKey);
+
+ if (!publicKey ||
+ bignum_cmp(publicKey->x, ec->publicKey.x) ||
+ bignum_cmp(publicKey->y, ec->publicKey.y))
+ {
+ ecdsa_freekey(ec);
+ ec = NULL;
+ }
+ ec_point_free(publicKey);
+
+ return ec;
+}
+
+static void *ecdsa_openssh_createkey(unsigned char **blob, int *len)
+{
+ char **b = (char **) blob;
+ char *p;
+ int slen;
+ struct ec_key *ec;
+ struct ec_curve *curve;
+ struct ec_point *publicKey;
+
+ getstring(b, len, &p, &slen);
+
+ if (!p) {
+ return NULL;
+ }
+ curve = ec_name_to_curve(p, slen);
+ if (!curve) return NULL;
+
+ ec = snew(struct ec_key);
+
+ ec->publicKey.curve = curve;
+ ec->publicKey.infinity = 0;
+ ec->publicKey.x = NULL;
+ ec->publicKey.y = NULL;
+ ec->publicKey.z = NULL;
+ if (!getmppoint(b, len, &ec->publicKey)) {
+ ecdsa_freekey(ec);
+ return NULL;
+ }
+ ec->privateKey = NULL;
+
+ if (!ec->publicKey.x || !ec->publicKey.y ||
+ bignum_cmp(ec->publicKey.x, curve->p) >= 0 ||
+ bignum_cmp(ec->publicKey.y, curve->p) >= 0)
+ {
+ ecdsa_freekey(ec);
+ return NULL;
+ }
+
+ ec->privateKey = getmp(b, len);
+ if (ec->privateKey == NULL)
+ {
+ ecdsa_freekey(ec);
+ return NULL;
+ }
+
+ /* Now check that the private key makes the public key */
+ publicKey = ecp_mul(&ec->publicKey.curve->G, ec->privateKey);
+ if (!publicKey)
+ {
+ ecdsa_freekey(ec);
+ return NULL;
+ }
+
+ if (bignum_cmp(ec->publicKey.x, publicKey->x) ||
+ bignum_cmp(ec->publicKey.y, publicKey->y))
+ {
+ /* Private key doesn't make the public key on the given curve */
+ ecdsa_freekey(ec);
+ ec_point_free(publicKey);
+ }
+
+ ec_point_free(publicKey);
+
+ return ec;
+}
+
+static int ecdsa_openssh_fmtkey(void *key, unsigned char *blob, int len)
+{
+ struct ec_key *ec = (struct ec_key *) key;
+
+ int pointlen = (bignum_bitcount(ec->publicKey.curve->p) + 7) / 8;
+
+ int namelen = ec_curve_to_name(ec->publicKey.curve, NULL, 0);
+
+ int bloblen =
+ 4 + namelen /* <LEN> nistpXXX */
+ + 4 + 1 + (pointlen * 2) /* <LEN> 0x04 pX pY */
+ + ssh2_bignum_length(ec->privateKey);
+
+ int i;
+
+ if (bloblen > len)
+ return bloblen;
+
+ bloblen = 0;
+
+ PUT_32BIT(blob+bloblen, namelen);
+ bloblen += 4;
+
+ bloblen += ec_curve_to_name(ec->publicKey.curve, blob+bloblen, namelen);
+
+ PUT_32BIT(blob+bloblen, 1 + (pointlen * 2));
+ bloblen += 4;
+ blob[bloblen++] = 0x04;
+ for (i = pointlen; i--; )
+ blob[bloblen++] = bignum_byte(ec->publicKey.x, i);
+ for (i = pointlen; i--; )
+ blob[bloblen++] = bignum_byte(ec->publicKey.y, i);
+
+ pointlen = (bignum_bitcount(ec->privateKey) + 8) / 8;
+ PUT_32BIT(blob+bloblen, pointlen);
+ bloblen += 4;
+ for (i = pointlen; i--; )
+ blob[bloblen++] = bignum_byte(ec->privateKey, i);
+
+ return bloblen;
+}
+
+static int ecdsa_pubkey_bits(void *blob, int len)
+{
+ struct ec_key *ec;
+ int ret;
+
+ ec = (struct ec_key*)ecdsa_newkey((char *) blob, len);
+ if (!ec)
+ return -1;
+ ret = ec->publicKey.curve->fieldBits;
+ ecdsa_freekey(ec);
+
+ return ret;
+}
+
+static char *ecdsa_fingerprint(void *key)
+{
+ struct ec_key *ec = (struct ec_key *) key;
+ struct MD5Context md5c;
+ unsigned char digest[16], lenbuf[4];
+ char *ret;
+ unsigned char *name;
+ int pointlen, namelen, i, j;
+
+ namelen = ec_curve_to_name(ec->publicKey.curve, NULL, 0);
+ name = snewn(namelen, unsigned char);
+ ec_curve_to_name(ec->publicKey.curve, name, namelen);
+
+ MD5Init(&md5c);
+
+ PUT_32BIT(lenbuf, namelen + 11);
+ MD5Update(&md5c, lenbuf, 4);
+ MD5Update(&md5c, (const unsigned char *)"ecdsa-sha2-", 11);
+ MD5Update(&md5c, name, namelen);
+
+ PUT_32BIT(lenbuf, namelen);
+ MD5Update(&md5c, lenbuf, 4);
+ MD5Update(&md5c, name, namelen);
+
+ pointlen = (bignum_bitcount(ec->publicKey.curve->p) + 7) / 8;
+ PUT_32BIT(lenbuf, 1 + (pointlen * 2));
+ MD5Update(&md5c, lenbuf, 4);
+ MD5Update(&md5c, (const unsigned char *)"\x04", 1);
+ for (i = pointlen; i--; ) {
+ unsigned char c = bignum_byte(ec->publicKey.x, i);
+ MD5Update(&md5c, &c, 1);
+ }
+ for (i = pointlen; i--; ) {
+ unsigned char c = bignum_byte(ec->publicKey.y, i);
+ MD5Update(&md5c, &c, 1);
+ }
+
+ MD5Final(digest, &md5c);
+
+ ret = snewn(11 + namelen + 1 + (16 * 3), char);
+
+ i = 11;
+ memcpy(ret, "ecdsa-sha2-", 11);
+ memcpy(ret+i, name, namelen);
+ i += namelen;
+ sfree(name);
+ ret[i++] = ' ';
+ for (j = 0; j < 16; j++)
+ i += sprintf(ret + i, "%s%02x", j ? ":" : "", digest[j]);
+
+ return ret;
+}
+
+static int ecdsa_verifysig(void *key, char *sig, int siglen,
+ char *data, int datalen)
+{
+ struct ec_key *ec = (struct ec_key *) key;
+ char *p;
+ int slen;
+ unsigned char digest[512 / 8];
+ int digestLen;
+ Bignum r, s;
+ int ret;
+
+ if (!ec->publicKey.x || !ec->publicKey.y || !ec->publicKey.curve)
+ return 0;
+
+ /* Check the signature curve matches the key curve */
+ getstring(&sig, &siglen, &p, &slen);
+ if (!p || slen < 11 || memcmp(p, "ecdsa-sha2-", 11)) {
+ return 0;
+ }
+ if (ec->publicKey.curve != ec_name_to_curve(p+11, slen-11)) {
+ return 0;
+ }
+
+ getstring(&sig, &siglen, &p, &slen);
+ r = getmp(&p, &slen);
+ if (!r) return 0;
+ s = getmp(&p, &slen);
+ if (!s) {
+ freebn(r);
+ return 0;
+ }
+
+ /* Perform correct hash function depending on curve size */
+ if (ec->publicKey.curve->fieldBits <= 256) {
+ SHA256_Simple(data, datalen, digest);
+ digestLen = 256 / 8;
+ } else if (ec->publicKey.curve->fieldBits <= 384) {
+ SHA384_Simple(data, datalen, digest);
+ digestLen = 384 / 8;
+ } else {
+ SHA512_Simple(data, datalen, digest);
+ digestLen = 512 / 8;
+ }
+
+ /* Verify the signature */
+ if (!_ecdsa_verify(&ec->publicKey, digest, digestLen, r, s)) {
+ ret = 0;
+ } else {
+ ret = 1;
+ }
+
+ freebn(r);
+ freebn(s);
+
+ return ret;
+}
+
+static unsigned char *ecdsa_sign(void *key, char *data, int datalen,
+ int *siglen)
+{
+ struct ec_key *ec = (struct ec_key *) key;
+ unsigned char digest[512 / 8];
+ int digestLen;
+ Bignum r = NULL, s = NULL;
+ unsigned char *buf, *p;
+ int rlen, slen, namelen;
+ int i;
+
+ if (!ec->privateKey || !ec->publicKey.curve) {
+ return NULL;
+ }
+
+ /* Perform correct hash function depending on curve size */
+ if (ec->publicKey.curve->fieldBits <= 256) {
+ SHA256_Simple(data, datalen, digest);
+ digestLen = 256 / 8;
+ } else if (ec->publicKey.curve->fieldBits <= 384) {
+ SHA384_Simple(data, datalen, digest);
+ digestLen = 384 / 8;
+ } else {
+ SHA512_Simple(data, datalen, digest);
+ digestLen = 512 / 8;
+ }
+
+ /* Do the signature */
+ _ecdsa_sign(ec->privateKey, ec->publicKey.curve, digest, digestLen, &r, &s);
+ if (!r || !s) {
+ if (r) freebn(r);
+ if (s) freebn(s);
+ return NULL;
+ }
+
+ rlen = (bignum_bitcount(r) + 8) / 8;
+ slen = (bignum_bitcount(s) + 8) / 8;
+
+ namelen = ec_curve_to_name(ec->publicKey.curve, NULL, 0);
+
+ /* Format the output */
+ *siglen = 8+11+namelen+rlen+slen+8;
+ buf = snewn(*siglen, unsigned char);
+ p = buf;
+ PUT_32BIT(p, 11+namelen);
+ p += 4;
+ memcpy(p, "ecdsa-sha2-", 11);
+ p += 11;
+ p += ec_curve_to_name(ec->publicKey.curve, p, namelen);
+ PUT_32BIT(p, rlen + slen + 8);
+ p += 4;
+ PUT_32BIT(p, rlen);
+ p += 4;
+ for (i = rlen; i--;)
+ *p++ = bignum_byte(r, i);
+ PUT_32BIT(p, slen);
+ p += 4;
+ for (i = slen; i--;)
+ *p++ = bignum_byte(s, i);
+
+ return buf;
+}
+
+const struct ssh_signkey ssh_ecdsa_nistp256 = {
+ ecdsa_newkey,
+ ecdsa_freekey,
+ ecdsa_fmtkey,
+ ecdsa_public_blob,
+ ecdsa_private_blob,
+ ecdsa_createkey,
+ ecdsa_openssh_createkey,
+ ecdsa_openssh_fmtkey,
+ ecdsa_pubkey_bits,
+ ecdsa_fingerprint,
+ ecdsa_verifysig,
+ ecdsa_sign,
+ "ecdsa-sha2-nistp256",
+ "ecdsa-sha2-nistp256",
+};
+
+const struct ssh_signkey ssh_ecdsa_nistp384 = {
+ ecdsa_newkey,
+ ecdsa_freekey,
+ ecdsa_fmtkey,
+ ecdsa_public_blob,
+ ecdsa_private_blob,
+ ecdsa_createkey,
+ ecdsa_openssh_createkey,
+ ecdsa_openssh_fmtkey,
+ ecdsa_pubkey_bits,
+ ecdsa_fingerprint,
+ ecdsa_verifysig,
+ ecdsa_sign,
+ "ecdsa-sha2-nistp384",
+ "ecdsa-sha2-nistp384",
+};
+
+const struct ssh_signkey ssh_ecdsa_nistp521 = {
+ ecdsa_newkey,
+ ecdsa_freekey,
+ ecdsa_fmtkey,
+ ecdsa_public_blob,
+ ecdsa_private_blob,
+ ecdsa_createkey,
+ ecdsa_openssh_createkey,
+ ecdsa_openssh_fmtkey,
+ ecdsa_pubkey_bits,
+ ecdsa_fingerprint,
+ ecdsa_verifysig,
+ ecdsa_sign,
+ "ecdsa-sha2-nistp521",
+ "ecdsa-sha2-nistp521",
+};
+
+/* ----------------------------------------------------------------------
+ * Exposed ECDH interface
+ */
+
+static Bignum ecdh_calculate(const Bignum private,
+ const struct ec_point *public)
+{
+ struct ec_point *p;
+ Bignum ret;
+ p = ecp_mul(public, private);
+ if (!p) return NULL;
+ ret = p->x;
+ p->x = NULL;
+ ec_point_free(p);
+ return ret;
+}
+
+void *ssh_ecdhkex_newkey(struct ec_curve *curve)
+{
+ struct ec_key *key = snew(struct ec_key);
+ struct ec_point *publicKey;
+ key->publicKey.curve = curve;
+ key->privateKey = bignum_random_in_range(One, key->publicKey.curve->n);
+ if (!key->privateKey) {
+ sfree(key);
+ return NULL;
+ }
+ publicKey = ecp_mul(&key->publicKey.curve->G, key->privateKey);
+ if (!publicKey) {
+ freebn(key->privateKey);
+ sfree(key);
+ return NULL;
+ }
+ key->publicKey.x = publicKey->x;
+ key->publicKey.y = publicKey->y;
+ key->publicKey.z = NULL;
+ sfree(publicKey);
+ return key;
+}
+
+char *ssh_ecdhkex_getpublic(void *key, int *len)
+{
+ struct ec_key *ec = (struct ec_key*)key;
+ char *point, *p;
+ int i;
+ int pointlen = (bignum_bitcount(ec->publicKey.curve->p) + 7) / 8;
+
+ *len = 1 + pointlen * 2;
+ point = (char*)snewn(*len, char);
+
+ p = point;
+ *p++ = 0x04;
+ for (i = pointlen; i--;)
+ *p++ = bignum_byte(ec->publicKey.x, i);
+ for (i = pointlen; i--;)
+ *p++ = bignum_byte(ec->publicKey.y, i);
+
+ return point;
+}
+
+Bignum ssh_ecdhkex_getkey(void *key, char *remoteKey, int remoteKeyLen)
+{
+ struct ec_key *ec = (struct ec_key*) key;
+ struct ec_point remote;
+
+ remote.curve = ec->publicKey.curve;
+ remote.infinity = 0;
+ if (!decodepoint(remoteKey, remoteKeyLen, &remote)) {
+ return NULL;
+ }
+
+ return ecdh_calculate(ec->privateKey, &remote);
+}
+
+void ssh_ecdhkex_freekey(void *key)
+{
+ ecdsa_freekey(key);
+}
+
+static const struct ssh_kex ssh_ec_kex_nistp256 = {
+ "ecdh-sha2-nistp256", NULL, KEXTYPE_ECDH, NULL, NULL, 0, 0, &ssh_sha256
+};
+
+static const struct ssh_kex ssh_ec_kex_nistp384 = {
+ "ecdh-sha2-nistp384", NULL, KEXTYPE_ECDH, NULL, NULL, 0, 0, &ssh_sha384
+};
+
+static const struct ssh_kex ssh_ec_kex_nistp521 = {
+ "ecdh-sha2-nistp521", NULL, KEXTYPE_ECDH, NULL, NULL, 0, 0, &ssh_sha512
+};
+
+static const struct ssh_kex *const ec_kex_list[] = {
+ &ssh_ec_kex_nistp256,
+ &ssh_ec_kex_nistp384,
+ &ssh_ec_kex_nistp521
+};
+
+const struct ssh_kexes ssh_ecdh_kex = {
+ sizeof(ec_kex_list) / sizeof(*ec_kex_list),
+ ec_kex_list
+};
projects / PuTTY.git / commitdiff