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Implement OpenSSH 9.x's NTRU Prime / Curve25519 kex.

Browse Source 
This consists of DJB's 'Streamlined NTRU Prime' quantum-resistant
cryptosystem, currently in round 3 of the NIST post-quantum key
exchange competition; it's run in parallel with ordinary Curve25519,
and generates a shared secret combining the output of both systems.

(Hence, even if you don't trust this newfangled NTRU Prime thing at
all, it's at least no _less_ secure than the kex you were using
already.)

As the OpenSSH developers point out, key exchange is the most urgent
thing to make quantum-resistant, even before working quantum computers
big enough to break crypto become available, because a break of the
kex algorithm can be applied retroactively to recordings of your past
sessions. By contrast, authentication is a real-time protocol, and can
only be broken by a quantum computer if there's one available to
attack you _already_.

I've implemented both sides of the mechanism, so that PuTTY and Uppity
both support it. In my initial testing, the two sides can both
interoperate with the appropriate half of OpenSSH, and also (of
course, but it would be embarrassing to mess it up) with each other.
This commit is contained in:
Simon Tatham
2022-04-15 17:19:47 +01:00
parent e59ee96554
commit faf1601a55
14 changed files with 2358 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

101
test/cryptsuite.py
View File

@ -1274,6 +1274,107 @@ class keygen(MyTestBase):
mr = miller_rabin_new(n)
self.assertEqual(miller_rabin_test(mr, 0x251), "failed")
class ntru(MyTestBase):
def testMultiply(self):
self.assertEqual(
ntru_ring_multiply([1,1,1,1,1,1], [1,1,1,1,1,1], 11, 59),
[1,2,3,4,5,6,5,4,3,2,1])
self.assertEqual(ntru_ring_multiply(
[1,0,1,2,0,0,1,2,0,1,2], [2,0,0,1,0,1,2,2,2,0,2], 11, 3),
[1,0,0,0,0,0,0,0,0,0,0])
def testInvert(self):
# Over GF(3), x^11-x-1 factorises as
# (x^3+x^2+2) * (x^8+2*x^7+x^6+2*x^4+2*x^3+x^2+x+1)
# so we expect that 2,0,1,1 has no inverse, being one of those factors.
self.assertEqual(ntru_ring_invert([0], 11, 3), None)
self.assertEqual(ntru_ring_invert([1], 11, 3),
[1,0,0,0,0,0,0,0,0,0,0])
self.assertEqual(ntru_ring_invert([2,0,1,1], 11, 3), None)
self.assertEqual(ntru_ring_invert([1,0,1,2,0,0,1,2,0,1,2], 11, 3),
[2,0,0,1,0,1,2,2,2,0,2])
self.assertEqual(ntru_ring_invert([1,0,1,2,0,0,1,2,0,1,2], 11, 59),
[1,26,10,1,38,48,34,37,53,3,53])
def testMod3Round3(self):
# Try a prime congruent to 1 mod 3
self.assertEqual(ntru_mod3([4,5,6,0,1,2,3], 7, 7),
[0,1,-1,0,1,-1,0])
self.assertEqual(ntru_round3([4,5,6,0,1,2,3], 7, 7),
[-3,-3,0,0,0,3,3])
# And one congruent to 2 mod 3
self.assertEqual(ntru_mod3([6,7,8,9,10,0,1,2,3,4,5], 11, 11),
[1,-1,0,1,-1,0,1,-1,0,1,-1])
self.assertEqual(ntru_round3([6,7,8,9,10,0,1,2,3,4,5], 11, 11),
[-6,-3,-3,-3,0,0,0,3,3,3,6])
def testBiasScale(self):
self.assertEqual(ntru_bias([0,1,2,3,4,5,6,7,8,9,10], 4, 11, 11),
[4,5,6,7,8,9,10,0,1,2,3])
self.assertEqual(ntru_scale([0,1,2,3,4,5,6,7,8,9,10], 4, 11, 11),
[0,4,8,1,5,9,2,6,10,3,7])
def testEncode(self):
# Test a small case. Worked through in detail:
#
# Pass 1:
# Input list is (89:123, 90:234, 344:345, 432:456, 222:567)
# (89:123, 90:234) -> (89+123*90 : 123*234) = (11159:28782)
# Emit low byte of 11159 = 0x97, and get (43:113)
# (344:345, 432:456) -> (344+345*432 : 345*456) = (149384:157320)
# Emit low byte of 149384 = 0x88, and get (583:615)
# Odd pair (222:567) is copied to end of new list
# Final list is (43:113, 583:615, 222:567)
# Pass 2:
# Input list is (43:113, 583:615, 222:567)
# (43:113, 583:615) -> (43+113*583, 113*615) = (65922:69495)
# Emit low byte of 65922 = 0x82, and get (257:272)
# Odd pair (222:567) is copied to end of new list
# Final list is (257:272, 222:567)
# Pass 3:
# Input list is (257:272, 222:567)
# (257:272, 222:567) -> (257+272*222, 272*567) = (60641:154224)
# Emit low byte of 60641 = 0xe1, and get (236:603)
# Final list is (236:603)
# Cleanup:
# Emit low byte of 236 = 0xec, and get (0:3)
# Emit low byte of 0 = 0x00, and get (0:1)
ms = [123,234,345,456,567]
rs = [89,90,344,432,222]
encoding = unhex('978882e1ec00')
sched = ntru_encode_schedule(ms)
self.assertEqual(sched.encode(rs), encoding)
self.assertEqual(sched.decode(encoding), rs)
# Encode schedules for sntrup761 public keys and ciphertexts
pubsched = ntru_encode_schedule([4591]*761)
self.assertEqual(pubsched.length(), 1158)
ciphersched = ntru_encode_schedule([1531]*761)
self.assertEqual(ciphersched.length(), 1007)
# Test round-trip encoding using those schedules
testlist = list(range(761))
pubtext = pubsched.encode(testlist)
self.assertEqual(pubsched.decode(pubtext), testlist)
ciphertext = ciphersched.encode(testlist)
self.assertEqual(ciphersched.decode(ciphertext), testlist)
def testCore(self):
# My own set of NTRU Prime parameters, satisfying all the
# requirements and tiny enough for convenient testing
p, q, w = 11, 59, 3
with random_prng('ntru keygen seed'):
keypair = ntru_keygen(p, q, w)
plaintext = ntru_gen_short(p, w)
ciphertext = ntru_encrypt(plaintext, ntru_pubkey(keypair), p, q)
recovered = ntru_decrypt(ciphertext, keypair)
self.assertEqual(plaintext, recovered)
class crypt(MyTestBase):
def testSSH1Fingerprint(self):
# Example key and reference fingerprint value generated by

29
test/testcrypt-func.h
View File

@ -352,6 +352,35 @@ FUNC(void, ecdh_key_getpublic, ARG(val_ecdh, key),
FUNC_WRAPPED(opt_val_string, ecdh_key_getkey, ARG(val_ecdh, key),
ARG(val_string_ptrlen, pub))
/*
* NTRU and its subroutines.
*/
FUNC_WRAPPED(int16_list, ntru_ring_multiply, ARG(int16_list, a),
ARG(int16_list, b), ARG(uint, p), ARG(uint, q))
FUNC_WRAPPED(opt_int16_list, ntru_ring_invert, ARG(int16_list, r),
ARG(uint, p), ARG(uint, q))
FUNC_WRAPPED(int16_list, ntru_mod3, ARG(int16_list, r),
ARG(uint, p), ARG(uint, q))
FUNC_WRAPPED(int16_list, ntru_round3, ARG(int16_list, r),
ARG(uint, p), ARG(uint, q))
FUNC_WRAPPED(int16_list, ntru_bias, ARG(int16_list, r),
ARG(uint, bias), ARG(uint, p), ARG(uint, q))
FUNC_WRAPPED(int16_list, ntru_scale, ARG(int16_list, r),
ARG(uint, scale), ARG(uint, p), ARG(uint, q))
FUNC_WRAPPED(val_ntruencodeschedule, ntru_encode_schedule, ARG(int16_list, ms))
FUNC(uint, ntru_encode_schedule_length, ARG(val_ntruencodeschedule, sched))
FUNC_WRAPPED(void, ntru_encode, ARG(val_ntruencodeschedule, sched),
ARG(int16_list, rs), ARG(out_val_string_binarysink, data))
FUNC_WRAPPED(opt_int16_list, ntru_decode, ARG(val_ntruencodeschedule, sched),
ARG(val_string_ptrlen, data))
FUNC_WRAPPED(int16_list, ntru_gen_short, ARG(uint, p), ARG(uint, w))
FUNC(val_ntrukeypair, ntru_keygen, ARG(uint, p), ARG(uint, q), ARG(uint, w))
FUNC_WRAPPED(int16_list, ntru_pubkey, ARG(val_ntrukeypair, keypair))
FUNC_WRAPPED(int16_list, ntru_encrypt, ARG(int16_list, plaintext),
ARG(int16_list, pubkey), ARG(uint, p), ARG(uint, q))
FUNC_WRAPPED(int16_list, ntru_decrypt, ARG(int16_list, ciphertext),
ARG(val_ntrukeypair, keypair))
/*
* RSA key exchange, and also the BinarySource get function
* get_ssh1_rsa_priv_agent, which is a convenient way to make an

169
test/testcrypt.c
View File

@ -35,6 +35,7 @@
#include "misc.h"
#include "mpint.h"
#include "crypto/ecc.h"
#include "crypto/ntru.h"
#include "proxy/cproxy.h"
static NORETURN PRINTF_LIKE(1, 2) void fatal_error(const char *p, ...)
@ -96,6 +97,8 @@ uint64_t prng_reseed_time_ms(void)
X(pgc, PrimeGenerationContext *, primegen_free_context(v)) \
X(pockle, Pockle *, pockle_free(v)) \
X(millerrabin, MillerRabin *, miller_rabin_free(v)) \
X(ntrukeypair, NTRUKeyPair *, ntru_keypair_free(v)) \
X(ntruencodeschedule, NTRUEncodeSchedule *, ntru_encode_schedule_free(v)) \
/* end of list */
typedef struct Value Value;
@ -221,6 +224,7 @@ typedef RsaSsh1Order TD_rsaorder;
typedef key_components *TD_keycomponents;
typedef const PrimeGenerationPolicy *TD_primegenpolicy;
typedef struct mpint_list TD_mpint_list;
typedef struct int16_list *TD_int16_list;
typedef PockleStatus TD_pocklestatus;
typedef struct mr_result TD_mr_result;
typedef Argon2Flavour TD_argon2flavour;
@ -385,6 +389,46 @@ static struct mpint_list get_mpint_list(BinarySource *in)
return mpl;
}
typedef struct int16_list {
size_t n;
uint16_t *integers;
} int16_list;
static void finaliser_int16_list_free(strbuf *out, void *vlist)
{
int16_list *list = (int16_list *)vlist;
sfree(list->integers);
sfree(list);
}
static int16_list *make_int16_list(size_t n)
{
int16_list *list = snew(int16_list);
list->n = n;
list->integers = snewn(n, uint16_t);
add_finaliser(finaliser_int16_list_free, list);
return list;
}
static int16_list *get_int16_list(BinarySource *in)
{
size_t n = get_uint(in);
int16_list *list = make_int16_list(n);
for (size_t i = 0; i < n; i++)
list->integers[i] = get_uint(in);
return list;
}
static void return_int16_list(strbuf *out, int16_list *list)
{
for (size_t i = 0; i < list->n; i++) {
if (i > 0)
put_byte(out, ',');
put_fmt(out, "%d", (int)(int16_t)list->integers[i]);
}
put_byte(out, '\n');
}
static void finaliser_return_uint(strbuf *out, void *ctx)
{
unsigned *uval = (unsigned *)ctx;
@ -543,6 +587,7 @@ NULLABLE_RETURN_WRAPPER(val_cipher, ssh_cipher *)
NULLABLE_RETURN_WRAPPER(val_hash, ssh_hash *)
NULLABLE_RETURN_WRAPPER(val_key, ssh_key *)
NULLABLE_RETURN_WRAPPER(val_mpint, mp_int *)
NULLABLE_RETURN_WRAPPER(int16_list, int16_list *)
static void handle_hello(BinarySource *in, strbuf *out)
{
@ -799,6 +844,130 @@ strbuf *ecdh_key_getkey_wrapper(ecdh_key *ek, ptrlen remoteKey)
return sb;
}
static void int16_list_resize(int16_list *list, unsigned p)
{
list->integers = sresize(list->integers, p, uint16_t);
for (size_t i = list->n; i < p; i++)
list->integers[i] = 0;
}
#if 0
static int16_list ntru_ring_to_list_and_free(uint16_t *out, unsigned p)
{
struct mpint_list mpl;
mpl.n = p;
mpl->integers = snewn(p, mp_int *);
for (unsigned i = 0; i < p; i++)
mpl->integers[i] = mp_from_integer((int16_t)out[i]);
sfree(out);
add_finaliser(finaliser_sfree, mpl->integers);
return mpl;
}
#endif
int16_list *ntru_ring_multiply_wrapper(
int16_list *a, int16_list *b, unsigned p, unsigned q)
{
int16_list_resize(a, p);
int16_list_resize(b, p);
int16_list *out = make_int16_list(p);
ntru_ring_multiply(out->integers, a->integers, b->integers, p, q);
return out;
}
int16_list *ntru_ring_invert_wrapper(int16_list *in, unsigned p, unsigned q)
{
int16_list_resize(in, p);
int16_list *out = make_int16_list(p);
unsigned success = ntru_ring_invert(out->integers, in->integers, p, q);
if (!success)
return NULL;
return out;
}
int16_list *ntru_mod3_wrapper(int16_list *in, unsigned p, unsigned q)
{
int16_list_resize(in, p);
int16_list *out = make_int16_list(p);
ntru_mod3(out->integers, in->integers, p, q);
return out;
}
int16_list *ntru_round3_wrapper(int16_list *in, unsigned p, unsigned q)
{
int16_list_resize(in, p);
int16_list *out = make_int16_list(p);
ntru_round3(out->integers, in->integers, p, q);
return out;
}
int16_list *ntru_bias_wrapper(int16_list *in, unsigned bias,
unsigned p, unsigned q)
{
int16_list_resize(in, p);
int16_list *out = make_int16_list(p);
ntru_bias(out->integers, in->integers, bias, p, q);
return out;
}
int16_list *ntru_scale_wrapper(int16_list *in, unsigned scale,
unsigned p, unsigned q)
{
int16_list_resize(in, p);
int16_list *out = make_int16_list(p);
ntru_scale(out->integers, in->integers, scale, p, q);
return out;
}
NTRUEncodeSchedule *ntru_encode_schedule_wrapper(int16_list *in)
{
return ntru_encode_schedule(in->integers, in->n);
}
void ntru_encode_wrapper(NTRUEncodeSchedule *sched, int16_list *rs,
BinarySink *bs)
{
ntru_encode(sched, rs->integers, bs);
}
int16_list *ntru_decode_wrapper(NTRUEncodeSchedule *sched, ptrlen data)
{
int16_list *out = make_int16_list(ntru_encode_schedule_nvals(sched));
ntru_decode(sched, out->integers, data);
return out;
}
int16_list *ntru_gen_short_wrapper(unsigned p, unsigned w)
{
int16_list *out = make_int16_list(p);
ntru_gen_short(out->integers, p, w);
return out;
}
int16_list *ntru_pubkey_wrapper(NTRUKeyPair *keypair)
{
unsigned p = ntru_keypair_p(keypair);
int16_list *out = make_int16_list(p);
memcpy(out->integers, ntru_pubkey(keypair), p*sizeof(uint16_t));
return out;
}
int16_list *ntru_encrypt_wrapper(int16_list *plaintext, int16_list *pubkey,
unsigned p, unsigned q)
{
int16_list *out = make_int16_list(p);
ntru_encrypt(out->integers, plaintext->integers, pubkey->integers, p, q);
return out;
}
int16_list *ntru_decrypt_wrapper(int16_list *ciphertext, NTRUKeyPair *keypair)
{
unsigned p = ntru_keypair_p(keypair);
int16_list *out = make_int16_list(p);
ntru_decrypt(out->integers, ciphertext->integers, keypair);
return out;
}
strbuf *rsa_ssh1_encrypt_wrapper(ptrlen input, RSAKey *key)
{
/* Fold the boolean return value in C into the string return value

9
test/testcrypt.py
View File

@ -199,6 +199,13 @@ def make_argword(arg, argtype, fnname, argindex, argname, to_preserve):
sublist.append(make_argword(val, ("val_mpint", False),
fnname, argindex, argname, to_preserve))
return b" ".join(coerce_to_bytes(sub) for sub in sublist)
if typename == "int16_list":
sublist = [make_argword(len(arg), ("uint", False),
fnname, argindex, argname, to_preserve)]
for val in arg:
sublist.append(make_argword(val & 0xFFFF, ("uint", False),
fnname, argindex, argname, to_preserve))
return b" ".join(coerce_to_bytes(sub) for sub in sublist)
raise TypeError(
"Can't convert {}() argument #{:d} ({}) to {} (value was {!r})".format(
fnname, argindex, argname, typename, arg))
@ -247,6 +254,8 @@ def make_retval(rettype, word, unpack_strings):
return word == b"true"
elif rettype in {"pocklestatus", "mr_result"}:
return word.decode("ASCII")
elif rettype == "int16_list":
return list(map(int, word.split(b',')))
raise TypeError("Can't deal with return value {!r} of type {!r}"
.format(word, rettype))

70
test/testsc.c
View File

@ -81,6 +81,7 @@
#include "misc.h"
#include "mpint.h"
#include "crypto/ecc.h"
#include "crypto/ntru.h"
static NORETURN PRINTF_LIKE(1, 2) void fatal_error(const char *p, ...)
{
@ -395,6 +396,7 @@ VOLATILE_WRAPPED_DEFN(static, size_t, looplimit, (size_t x))
HASHES(HASH_TESTLIST, X) \
X(argon2) \
X(primegen_probabilistic) \
X(ntru) \
/* end of list */
static void test_mp_get_nbits(void)
@ -1556,6 +1558,74 @@ static void test_primegen_probabilistic(void)
test_primegen(&primegen_probabilistic);
}
static void test_ntru(void)
{
unsigned p = 11, q = 59, w = 3;
uint16_t *pubkey_orig = snewn(p, uint16_t);
uint16_t *pubkey_check = snewn(p, uint16_t);
uint16_t *pubkey = snewn(p, uint16_t);
uint16_t *plaintext = snewn(p, uint16_t);
uint16_t *ciphertext = snewn(p, uint16_t);
strbuf *buffer = strbuf_new();
strbuf_append(buffer, 16384);
BinarySource src[1];
for (size_t i = 0; i < looplimit(32); i++) {
while (true) {
random_advance_counter();
struct random_state st = random_get_state();
NTRUKeyPair *keypair = ntru_keygen_attempt(p, q, w);
if (keypair) {
memcpy(pubkey_orig, ntru_pubkey(keypair),
p*sizeof(*pubkey_orig));
ntru_keypair_free(keypair);
random_set_state(st);
log_start();
NTRUKeyPair *keypair = ntru_keygen_attempt(p, q, w);
memcpy(pubkey_check, ntru_pubkey(keypair),
p*sizeof(*pubkey_check));
ntru_gen_short(plaintext, p, w);
ntru_encrypt(ciphertext, plaintext, pubkey, p, w);
ntru_decrypt(plaintext, ciphertext, keypair);
strbuf_clear(buffer);
ntru_encode_pubkey(ntru_pubkey(keypair), p, q,
BinarySink_UPCAST(buffer));
BinarySource_BARE_INIT_PL(src, ptrlen_from_strbuf(buffer));
ntru_decode_pubkey(pubkey, p, q, src);
strbuf_clear(buffer);
ntru_encode_ciphertext(ciphertext, p, q,
BinarySink_UPCAST(buffer));
BinarySource_BARE_INIT_PL(src, ptrlen_from_strbuf(buffer));
ntru_decode_ciphertext(ciphertext, keypair, src);
strbuf_clear(buffer);
ntru_encode_plaintext(plaintext, p, BinarySink_UPCAST(buffer));
log_end();
break;
}
assert(!memcmp(pubkey_orig, pubkey_check,
p*sizeof(*pubkey_check)));
}
}
sfree(pubkey_orig);
sfree(pubkey_check);
sfree(pubkey);
sfree(plaintext);
sfree(ciphertext);
strbuf_free(buffer);
}
static const struct test tests[] = {
#define STRUCT_TEST(X) { #X, test_##X },
TESTLIST(STRUCT_TEST)