Convert SSL_ECDH_CTX to C++.
SSLECDHContext has the acronyms problem, so I went with SSLKeyShare to
match the TLS 1.3 terminology. It's also a little shorter. Accept and
Finish, for now, take raw output pointers in anticipation of some
bssl::Array and maybe bssl::CleansedArray types.
Bug: 132
Change-Id: I427c7c0eac95704f3ad093676c504c2848f5acb9
Reviewed-on: https://boringssl-review.googlesource.com/18265
Reviewed-by: Steven Valdez <svaldez@google.com>
diff --git a/ssl/ssl_key_share.cc b/ssl/ssl_key_share.cc
new file mode 100644
index 0000000..eb61535
--- /dev/null
+++ b/ssl/ssl_key_share.cc
@@ -0,0 +1,245 @@
+/* Copyright (c) 2015, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <openssl/ssl.h>
+
+#include <assert.h>
+#include <string.h>
+
+#include <openssl/bn.h>
+#include <openssl/bytestring.h>
+#include <openssl/curve25519.h>
+#include <openssl/ec.h>
+#include <openssl/err.h>
+#include <openssl/mem.h>
+#include <openssl/nid.h>
+
+#include "internal.h"
+#include "../crypto/internal.h"
+
+
+namespace bssl {
+
+namespace {
+
+class ECKeyShare : public SSLKeyShare {
+ public:
+ ECKeyShare(int nid, uint16_t group_id) : nid_(nid), group_id_(group_id) {}
+ ~ECKeyShare() override {}
+
+ uint16_t GroupID() const override { return group_id_; }
+
+ bool Offer(CBB *out) override {
+ assert(!private_key_);
+ /* Set up a shared |BN_CTX| for all operations. */
+ UniquePtr<BN_CTX> bn_ctx(BN_CTX_new());
+ if (!bn_ctx) {
+ return false;
+ }
+ BN_CTXScope scope(bn_ctx.get());
+
+ /* Generate a private key. */
+ UniquePtr<EC_GROUP> group(EC_GROUP_new_by_curve_name(nid_));
+ private_key_.reset(BN_new());
+ if (!group || !private_key_ ||
+ !BN_rand_range_ex(private_key_.get(), 1,
+ EC_GROUP_get0_order(group.get()))) {
+ return false;
+ }
+
+ /* Compute the corresponding public key and serialize it. */
+ UniquePtr<EC_POINT> public_key(EC_POINT_new(group.get()));
+ if (!public_key ||
+ !EC_POINT_mul(group.get(), public_key.get(), private_key_.get(), NULL,
+ NULL, bn_ctx.get()) ||
+ !EC_POINT_point2cbb(out, group.get(), public_key.get(),
+ POINT_CONVERSION_UNCOMPRESSED, bn_ctx.get())) {
+ return false;
+ }
+
+ return true;
+ }
+
+ bool Finish(uint8_t **out_secret, size_t *out_secret_len, uint8_t *out_alert,
+ const uint8_t *peer_key, size_t peer_key_len) override {
+ assert(private_key_);
+ *out_alert = SSL_AD_INTERNAL_ERROR;
+
+ /* Set up a shared |BN_CTX| for all operations. */
+ UniquePtr<BN_CTX> bn_ctx(BN_CTX_new());
+ if (!bn_ctx) {
+ return false;
+ }
+ BN_CTXScope scope(bn_ctx.get());
+
+ UniquePtr<EC_GROUP> group(EC_GROUP_new_by_curve_name(nid_));
+ if (!group) {
+ return false;
+ }
+
+ UniquePtr<EC_POINT> peer_point(EC_POINT_new(group.get()));
+ UniquePtr<EC_POINT> result(EC_POINT_new(group.get()));
+ BIGNUM *x = BN_CTX_get(bn_ctx.get());
+ if (!peer_point || !result || !x) {
+ return false;
+ }
+
+ if (!EC_POINT_oct2point(group.get(), peer_point.get(), peer_key,
+ peer_key_len, bn_ctx.get())) {
+ *out_alert = SSL_AD_DECODE_ERROR;
+ return false;
+ }
+
+ /* Compute the x-coordinate of |peer_key| * |private_key_|. */
+ if (!EC_POINT_mul(group.get(), result.get(), NULL, peer_point.get(),
+ private_key_.get(), bn_ctx.get()) ||
+ !EC_POINT_get_affine_coordinates_GFp(group.get(), result.get(), x, NULL,
+ bn_ctx.get())) {
+ return false;
+ }
+
+ /* Encode the x-coordinate left-padded with zeros. */
+ size_t secret_len = (EC_GROUP_get_degree(group.get()) + 7) / 8;
+ UniquePtr<uint8_t> secret((uint8_t *)OPENSSL_malloc(secret_len));
+ if (!secret || !BN_bn2bin_padded(secret.get(), secret_len, x)) {
+ return false;
+ }
+
+ *out_secret = secret.release();
+ *out_secret_len = secret_len;
+ return true;
+ }
+
+ private:
+ UniquePtr<BIGNUM> private_key_;
+ int nid_;
+ uint16_t group_id_;
+};
+
+class X25519KeyShare : public SSLKeyShare {
+ public:
+ X25519KeyShare() {}
+ ~X25519KeyShare() override {
+ OPENSSL_cleanse(private_key_, sizeof(private_key_));
+ }
+
+ uint16_t GroupID() const override { return SSL_CURVE_X25519; }
+
+ bool Offer(CBB *out) override {
+ uint8_t public_key[32];
+ X25519_keypair(public_key, private_key_);
+ return !!CBB_add_bytes(out, public_key, sizeof(public_key));
+ }
+
+ bool Finish(uint8_t **out_secret, size_t *out_secret_len, uint8_t *out_alert,
+ const uint8_t *peer_key, size_t peer_key_len) override {
+ *out_alert = SSL_AD_INTERNAL_ERROR;
+
+ UniquePtr<uint8_t> secret((uint8_t *)OPENSSL_malloc(32));
+ if (!secret) {
+ OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
+ return false;
+ }
+
+ if (peer_key_len != 32 || !X25519(secret.get(), private_key_, peer_key)) {
+ *out_alert = SSL_AD_DECODE_ERROR;
+ OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_ECPOINT);
+ return false;
+ }
+
+ *out_secret = secret.release();
+ *out_secret_len = 32;
+ return true;
+ }
+
+ private:
+ uint8_t private_key_[32];
+};
+
+const struct {
+ int nid;
+ uint16_t group_id;
+ const char name[8];
+} kNamedGroups[] = {
+ {NID_secp224r1, SSL_CURVE_SECP224R1, "P-224"},
+ {NID_X9_62_prime256v1, SSL_CURVE_SECP256R1, "P-256"},
+ {NID_secp384r1, SSL_CURVE_SECP384R1, "P-384"},
+ {NID_secp521r1, SSL_CURVE_SECP521R1, "P-521"},
+ {NID_X25519, SSL_CURVE_X25519, "X25519"},
+};
+
+} // namespace
+
+UniquePtr<SSLKeyShare> SSLKeyShare::Create(uint16_t group_id) {
+ switch (group_id) {
+ case SSL_CURVE_SECP224R1:
+ return UniquePtr<SSLKeyShare>(
+ New<ECKeyShare>(NID_secp224r1, SSL_CURVE_SECP224R1));
+ case SSL_CURVE_SECP256R1:
+ return UniquePtr<SSLKeyShare>(
+ New<ECKeyShare>(NID_X9_62_prime256v1, SSL_CURVE_SECP256R1));
+ case SSL_CURVE_SECP384R1:
+ return UniquePtr<SSLKeyShare>(
+ New<ECKeyShare>(NID_secp384r1, SSL_CURVE_SECP384R1));
+ case SSL_CURVE_SECP521R1:
+ return UniquePtr<SSLKeyShare>(
+ New<ECKeyShare>(NID_secp521r1, SSL_CURVE_SECP521R1));
+ case SSL_CURVE_X25519:
+ return UniquePtr<SSLKeyShare>(New<X25519KeyShare>());
+ default:
+ return nullptr;
+ }
+}
+
+bool SSLKeyShare::Accept(CBB *out_public_key, uint8_t **out_secret,
+ size_t *out_secret_len, uint8_t *out_alert,
+ const uint8_t *peer_key, size_t peer_key_len) {
+ *out_alert = SSL_AD_INTERNAL_ERROR;
+ return Offer(out_public_key) &&
+ Finish(out_secret, out_secret_len, out_alert, peer_key, peer_key_len);
+}
+
+int ssl_nid_to_group_id(uint16_t *out_group_id, int nid) {
+ for (const auto &group : kNamedGroups) {
+ if (group.nid == nid) {
+ *out_group_id = group.group_id;
+ return 1;
+ }
+ }
+ return 0;
+}
+
+int ssl_name_to_group_id(uint16_t *out_group_id, const char *name, size_t len) {
+ for (const auto &group : kNamedGroups) {
+ if (len == strlen(group.name) &&
+ !strncmp(group.name, name, len)) {
+ *out_group_id = group.group_id;
+ return 1;
+ }
+ }
+ return 0;
+}
+
+} // namespace bssl
+
+using namespace bssl;
+
+const char* SSL_get_curve_name(uint16_t group_id) {
+ for (const auto &group : kNamedGroups) {
+ if (group.group_id == group_id) {
+ return group.name;
+ }
+ }
+ return nullptr;
+}
