Integrate ed25519-donna (Not yet used).

Integrate ed25519-donna into the build process, and provide an
interface that matches the `ref10` code.  Apart from the blinding and
Curve25519 key conversion, this functions as a drop-in replacement for
ref10 (verified by modifying crypto_ed25519.c).

Tests pass, and the benchmarks claim it is quite a bit faster, however
actually using the code requires additional integration work.

.gitignore

@@ -144,6 +144,8 @@ cscope.*
 # /src/ext/
 /src/ext/ed25519/ref10/libed25519_ref10.a
 /src/ext/ed25519/ref10/libed25519_ref10.lib
+/src/ext/ed25519/donna/libed25519_donna.a
+/src/ext/ed25519/donna/libed25519_donna.lib
 
 # /src/or/
 /src/or/Makefile

src/common/include.am

@@ -43,6 +43,7 @@ endif
 endif
 
 LIBDONNA += $(LIBED25519_REF10)
+LIBDONNA += $(LIBED25519_DONNA)
 
 if THREADS_PTHREADS
 threads_impl_source=src/common/compat_pthreads.c

src/ext/ed25519/donna/README.tor

@@ -0,0 +1,32 @@
+
+We've made the following changes to the stock ed25519-donna from
+as of 8757bd4cd209cb032853ece0ce413f122eef212c.
+
+ * Tor uses copies of `ed25519-donna.h` and `ed25519.c`, named
+   `ed25519_donna_tor.h` and `ed25591_tor.c`.
+
+   The main functional differences between the standard ed25519-donna
+   and the Tor specific version are:
+
+    * The external interface has been reworked to match that provided
+       by Tor's copy of the SUPERCOP `ref10` code.
+
+    * The secret (aka private) key is now stored/used in expanded form.
+
+    * The internal math tests from `test-internals.c` have been wrapped
+      in a function and the entire file is included to allow for
+      runtime validation.
+
+ * `ED25519_FN(ed25519_randombytes_unsafe)` is now static.
+
+ * `ed25519-randombytes-custom.h` has the appropriate code to call
+    Tor's `crypto_rand()` routine, instead of directly using OpenSSL's
+    CSPRNG.
+
+ * OSX pollutes the global namespace with an `ALIGN` macro, which is
+   undef-ed right before the donna `ALIGN` macro is defined.
+
+ * If building with Clang's AddressSanitizer, disable inline assembly
+   since the compilation will fail in `ge25519_scalarmult_base_choose_niels`
+   on x86_64 targets due to running out of registers.
+

src/ext/ed25519/donna/ed25519-donna-portable.h

@@ -20,6 +20,8 @@
 	#include <sys/param.h>
 	#define DONNA_INLINE inline __attribute__((always_inline))
 	#define DONNA_NOINLINE __attribute__((noinline))
+	/* Tor: OSX pollutes the global namespace with an ALIGN macro. */
+	#undef ALIGN
 	#define ALIGN(x) __attribute__((aligned(x)))
 	#define ROTL32(a,b) (((a) << (b)) | ((a) >> (32 - b)))
 	#define ROTR32(a,b) (((a) >> (b)) | ((a) << (32 - b)))
@@ -129,6 +131,19 @@ static inline void U64TO8_LE(unsigned char *p, const uint64_t v) {
 }
 #endif
 
+/* Tor: Detect and disable inline assembly when clang's AddressSanitizer
+ * is present, due to compilation failing because it runs out of registers.
+ *
+ * The alternative is to annotate `ge25519_scalarmult_base_choose_niels`
+ * and selectively disable AddressSanitizer insturmentation, however doing
+ * things this way results in a "more sanitized" binary.
+ */
+#if defined(__has_feature)
+	#if __has_feature(address_sanitizer)
+		#define ED25519_NO_INLINE_ASM
+	#endif
+#endif
+
 #include <stdlib.h>
 #include <string.h>
 

src/ext/ed25519/donna/ed25519-randombytes-custom.h

@@ -6,3 +6,12 @@
 	ed25519_randombytes_unsafe is used by the batch verification function
 	to create random scalars
 */
+
+/* Tor: Instead of calling OpenSSL's CSPRNG directly, call the wrapper. */
+#include "crypto.h"
+
+static void
+ED25519_FN(ed25519_randombytes_unsafe) (void *p, size_t len)
+{
+  crypto_rand(p, len);
+}

src/ext/ed25519/donna/ed25519_donna_tor.h

@@ -0,0 +1,24 @@
+/* Added for Tor. */
+#ifndef SRC_EXT_ED25519_DONNA_H_INCLUDED_
+#define SRC_EXT_ED25519_DONNA_H_INCLUDED_
+#include <torint.h>
+
+typedef unsigned char curved25519_key[32];
+
+int ed25519_sign_open_batch_donna(const unsigned char **m, size_t *mlen, const unsigned char **pk, const unsigned char **RS, size_t num, int *valid);
+void curved25519_scalarmult_basepoint_donna(curved25519_key pk, const curved25519_key e);
+
+/* Tor specific interface to match the `ref10` glue code. */
+int ed25519_donna_selftest(void);
+int ed25519_donna_seckey(unsigned char *sk);
+int ed25519_donna_seckey_expand(unsigned char *sk, const unsigned char *sk_seed);
+int ed25519_donna_pubkey(unsigned char *pk, const unsigned char *sk);
+int ed25519_donna_keygen(unsigned char *pk, unsigned char *sk);
+
+int ed25519_donna_open(const unsigned char *signature, const unsigned char *m,
+  size_t mlen, const unsigned char *pk);
+
+int ed25519_donna_sign(unsigned char *sig, const unsigned char *m, size_t mlen,
+  const unsigned char *sk, const unsigned char *pk);
+
+#endif

src/ext/ed25519/donna/ed25519_tor.c

@@ -0,0 +1,240 @@
+/*
+  Public domain by Andrew M. <liquidsun@gmail.com>
+
+  Ed25519 reference implementation using Ed25519-donna
+*/
+
+/*
+  Tor specific notes:
+
+  This file is used by Tor instead of `ed25519.c` as the number of
+  changes/additions is non-trivial.
+
+  Tor modifications to `ed25519.c`:
+   * 'Tab` -> '  '.
+   * Include `ed25519_donna_tor.h` instead of `ed25519.h`.
+
+   * The external interface has been reworked to match that provided
+     by Tor's copy of the SUPERCOP `ref10` code.
+
+   * The secret (aka private) key is now stored/used in expanded form.
+
+   * The internal math tests from `test-internals.c` have been wrapped
+     in a function and the entire file is included to allow for
+     runtime validation.
+ */
+
+
+/* define ED25519_SUFFIX to have it appended to the end of each public function */
+#if !defined(ED25519_SUFFIX)
+#define ED25519_SUFFIX
+#endif
+
+#define ED25519_FN3(fn,suffix) fn##suffix
+#define ED25519_FN2(fn,suffix) ED25519_FN3(fn,suffix)
+#define ED25519_FN(fn)         ED25519_FN2(fn,ED25519_SUFFIX)
+
+
+#include "ed25519-donna.h"
+#include "ed25519_donna_tor.h"
+#include "ed25519-randombytes.h"
+#include "ed25519-hash.h"
+
+typedef unsigned char ed25519_signature[64];
+typedef unsigned char ed25519_public_key[32];
+typedef unsigned char ed25519_secret_key[32];
+
+static int ED25519_FN(ed25519_sign_open) (const unsigned char *m, size_t mlen,
+  const ed25519_public_key pk, const ed25519_signature RS);
+
+
+/*
+  Generates a (extsk[0..31]) and aExt (extsk[32..63])
+*/
+
+DONNA_INLINE static void
+ed25519_extsk(hash_512bits extsk, const ed25519_secret_key sk) {
+  ed25519_hash(extsk, sk, 32);
+  extsk[0] &= 248;
+  extsk[31] &= 127;
+  extsk[31] |= 64;
+}
+
+static void
+ed25519_hram(hash_512bits hram, const ed25519_signature RS, const ed25519_public_key pk, const unsigned char *m, size_t mlen) {
+  ed25519_hash_context ctx;
+  ed25519_hash_init(&ctx);
+  ed25519_hash_update(&ctx, RS, 32);
+  ed25519_hash_update(&ctx, pk, 32);
+  ed25519_hash_update(&ctx, m, mlen);
+  ed25519_hash_final(&ctx, hram);
+}
+
+static int
+ED25519_FN(ed25519_sign_open) (const unsigned char *m, size_t mlen, const ed25519_public_key pk, const ed25519_signature RS) {
+  ge25519 ALIGN(16) R, A;
+  hash_512bits hash;
+  bignum256modm hram, S;
+  unsigned char checkR[32];
+
+  if ((RS[63] & 224) || !ge25519_unpack_negative_vartime(&A, pk))
+    return -1;
+
+  /* hram = H(R,A,m) */
+  ed25519_hram(hash, RS, pk, m, mlen);
+  expand256_modm(hram, hash, 64);
+
+  /* S */
+  expand256_modm(S, RS + 32, 32);
+
+  /* SB - H(R,A,m)A */
+  ge25519_double_scalarmult_vartime(&R, &A, hram, S);
+  ge25519_pack(checkR, &R);
+
+  /* check that R = SB - H(R,A,m)A */
+  return ed25519_verify(RS, checkR, 32) ? 0 : -1;
+}
+
+#include "ed25519-donna-batchverify.h"
+
+/*
+  Fast Curve25519 basepoint scalar multiplication
+*/
+
+void
+ED25519_FN(curved25519_scalarmult_basepoint) (curved25519_key pk, const curved25519_key e) {
+  curved25519_key ec;
+  bignum256modm s;
+  bignum25519 ALIGN(16) yplusz, zminusy;
+  ge25519 ALIGN(16) p;
+  size_t i;
+
+  /* clamp */
+  for (i = 0; i < 32; i++) ec[i] = e[i];
+  ec[0] &= 248;
+  ec[31] &= 127;
+  ec[31] |= 64;
+
+  expand_raw256_modm(s, ec);
+
+  /* scalar * basepoint */
+  ge25519_scalarmult_base_niels(&p, ge25519_niels_base_multiples, s);
+
+  /* u = (y + z) / (z - y) */
+  curve25519_add(yplusz, p.y, p.z);
+  curve25519_sub(zminusy, p.z, p.y);
+  curve25519_recip(zminusy, zminusy);
+  curve25519_mul(yplusz, yplusz, zminusy);
+  curve25519_contract(pk, yplusz);
+}
+
+/*
+   Tor has a specific idea of how an Ed25519 implementaion should behave.
+   Implement such a beast using the ed25519-donna primitives/internals.
+
+    * Private key generation using Tor's CSPRNG.
+
+    * Routines that deal with the private key now use the expanded form.
+ */
+
+int
+ed25519_donna_seckey(unsigned char *sk)
+{
+  ed25519_secret_key seed;
+
+  if (crypto_strongest_rand(seed, 32))
+    return -1;
+
+  ed25519_extsk(sk, seed);
+
+  memwipe(seed, 0, sizeof(seed));
+
+  return 0;
+}
+
+int
+ed25519_donna_seckey_expand(unsigned char *sk, const unsigned char *skseed)
+{
+  ed25519_extsk(sk, skseed);
+
+  return 0;
+}
+
+int
+ed25519_donna_pubkey(unsigned char *pk, const unsigned char *sk)
+{
+  bignum256modm a;
+  ge25519 ALIGN(16) A;
+
+  /* A = aB */
+  expand256_modm(a, sk, 32);
+  ge25519_scalarmult_base_niels(&A, ge25519_niels_base_multiples, a);
+  ge25519_pack(pk, &A);
+
+  return 0;
+}
+
+int
+ed25519_donna_keygen(unsigned char *pk, unsigned char *sk)
+{
+  int ok;
+  ok = ed25519_donna_seckey(sk);
+  ed25519_donna_pubkey(pk, sk);
+
+  return ok;
+}
+
+int
+ed25519_donna_open(const unsigned char *signature, const unsigned char *m,
+  size_t mlen, const unsigned char *pk)
+{
+  /* Wrap the ed25519-donna routine, since it is also used by the batch
+   * verification code.
+   */
+  return ED25519_FN(ed25519_sign_open)(m, mlen, pk, signature);
+}
+
+int
+ed25519_donna_sign(unsigned char *sig, const unsigned char *m, size_t mlen,
+  const unsigned char *sk, const unsigned char *pk)
+{
+  ed25519_hash_context ctx;
+  bignum256modm r, S, a;
+  ge25519 ALIGN(16) R;
+  hash_512bits hashr, hram;
+
+  /* This is equivalent to the removed `ED25519_FN(ed25519_sign)` routine,
+   * except that the key expansion step is omitted as sk already is in expanded
+   * form.
+   */
+
+  /* r = H(aExt[32..64], m) */
+  ed25519_hash_init(&ctx);
+  ed25519_hash_update(&ctx, sk + 32, 32);
+  ed25519_hash_update(&ctx, m, mlen);
+  ed25519_hash_final(&ctx, hashr);
+  expand256_modm(r, hashr, 64);
+
+  /* R = rB */
+  ge25519_scalarmult_base_niels(&R, ge25519_niels_base_multiples, r);
+  ge25519_pack(sig, &R);
+
+  /* S = H(R,A,m).. */
+  ed25519_hram(hram, sig, pk, m, mlen);
+  expand256_modm(S, hram, 64);
+
+  /* S = H(R,A,m)a */
+  expand256_modm(a, sk, 32);
+  mul256_modm(S, S, a);
+
+  /* S = (r + H(R,A,m)a) */
+  add256_modm(S, S, r);
+
+  /* S = (r + H(R,A,m)a) mod L */
+  contract256_modm(sig + 32, S);
+
+  return 0;
+}
+
+#include "test-internals.c"
+

src/ext/ed25519/donna/test-internals.c

@@ -1,19 +1,22 @@
-#include <stdio.h>
+/* Tor: Removed, file is inclued in ed25519.c instead. */
-#include "ed25519-donna.h"
+/* #include <stdio.h> */
+/* #include "ed25519-donna.h" */
 
 static int
-test_adds() {
+test_adds(void) {
 #if defined(HAVE_UINT128) && !defined(ED25519_SSE2)
 	/* largest result for each limb from a mult or square: all elements except r1 reduced, r1 overflowed as far as possible */
 	static const bignum25519 max_bignum = {
 		0x7ffffffffffff,0x8000000001230,0x7ffffffffffff,0x7ffffffffffff,0x7ffffffffffff
 	};
 
+#if 0
 	/* what max_bignum should fully reduce to */
 	static const unsigned char max_bignum_raw[32] = {
 		0x12,0x00,0x00,0x00,0x00,0x00,0x88,0x91,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
 		0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
 	};
+#endif
 
 	/* (max_bignum + max_bignum)^2 */
 	static const unsigned char max_bignum2_squared_raw[32] = {
@@ -46,9 +49,9 @@ test_adds() {
 	};
 #endif
 	unsigned char result[32];
-	static const bignum25519 ALIGN(16) zero = {0};
+	/* static const bignum25519 ALIGN(16) zero = {0}; */
-	bignum25519 ALIGN(16) a, b, c;
+	bignum25519 ALIGN(16) a, b /* , c */;
-	size_t i;
+	/* size_t i; */
 
 	/* a = (max_bignum + max_bignum) */
 	curve25519_add(a, max_bignum, max_bignum);
@@ -80,7 +83,7 @@ test_adds() {
 }
 
 static int
-test_subs() {
+test_subs(void) {
 #if defined(HAVE_UINT128) && !defined(ED25519_SSE2)
 	/* largest result for each limb from a mult or square: all elements except r1 reduced, r1 overflowed as far as possible */
 	static const bignum25519 max_bignum = {
@@ -119,8 +122,8 @@ test_subs() {
 #endif
 	unsigned char result[32];
 	static const bignum25519 ALIGN(16) zero = {0};
-	bignum25519 ALIGN(16) a, b, c;
+	bignum25519 ALIGN(16) a, b /* , c */;
-	size_t i;
+	/* size_t i; */
 
 	/* a = max_bignum - 0, which expands to 2p + max_bignum - 0 */
 	curve25519_sub(a, max_bignum, zero);
@@ -158,7 +161,8 @@ test_subs() {
 	return 0;
 }
 
-
+/* Tor: Removed, tests are invoked as a function instead. */
+#if 0
 int
 main() {
 	int ret = 0;
@@ -172,5 +176,15 @@ main() {
 	if (!ret) printf("success\n");
 	return ret;
 }
+#endif
 
+/* Tor: Added for initialization self-testing. */
+int
+ed25519_donna_selftest(void)
+{
+	int ret = 0;
+	ret |= test_adds();
+	ret |= test_subs();
+	return (ret == 0) ? 0 : -1;
+}
 

src/ext/include.am

@@ -93,3 +93,44 @@ noinst_HEADERS += $(ED25519_REF10_HDRS)
 LIBED25519_REF10=src/ext/ed25519/ref10/libed25519_ref10.a
 noinst_LIBRARIES += $(LIBED25519_REF10)
 
+src_ext_ed25519_donna_libed25519_donna_a_CFLAGS= \
+  -DED25519_CUSTOMRANDOM \
+  -DED25519_SUFFIX=_donna
+
+src_ext_ed25519_donna_libed25519_donna_a_SOURCES= \
+	src/ext/ed25519/donna/ed25519_tor.c
+
+ED25519_DONNA_HDRS = \
+	src/ext/ed25519/donna/curve25519-donna-32bit.h \
+	src/ext/ed25519/donna/curve25519-donna-64bit.h \
+	src/ext/ed25519/donna/curve25519-donna-helpers.h \
+	src/ext/ed25519/donna/curve25519-donna-sse2.h \
+	src/ext/ed25519/donna/ed25519-donna-32bit-sse2.h \
+	src/ext/ed25519/donna/ed25519-donna-32bit-tables.h \
+	src/ext/ed25519/donna/ed25519-donna-64bit-sse2.h \
+	src/ext/ed25519/donna/ed25519-donna-64bit-tables.h \
+	src/ext/ed25519/donna/ed25519-donna-64bit-x86-32bit.h \
+	src/ext/ed25519/donna/ed25519-donna-64bit-x86.h \
+	src/ext/ed25519/donna/ed25519-donna-basepoint-table.h \
+	src/ext/ed25519/donna/ed25519-donna-batchverify.h \
+	src/ext/ed25519/donna/ed25519-donna.h \
+	src/ext/ed25519/donna/ed25519-donna-impl-base.h \
+	src/ext/ed25519/donna/ed25519-donna-impl-sse2.h \
+	src/ext/ed25519/donna/ed25519-donna-portable.h \
+	src/ext/ed25519/donna/ed25519-donna-portable-identify.h \
+	src/ext/ed25519/donna/ed25519_donna_tor.h \
+	src/ext/ed25519/donna/ed25519.h \
+	src/ext/ed25519/donna/ed25519-hash-custom.h \
+	src/ext/ed25519/donna/ed25519-hash.h \
+	src/ext/ed25519/donna/ed25519-randombytes-custom.h \
+	src/ext/ed25519/donna/ed25519-randombytes.h \
+	src/ext/ed25519/donna/modm-donna-32bit.h \
+	src/ext/ed25519/donna/modm-donna-64bit.h \
+	src/ext/ed25519/donna/regression.h \
+	src/ext/ed25519/donna/test-ticks.h
+
+noinst_HEADERS += $(ED25519_DONNA_HDRS)
+
+LIBED25519_DONNA=src/ext/ed25519/donna/libed25519_donna.a
+noinst_LIBRARIES += $(LIBED25519_DONNA)
+