From 1e1242604eb0fd510fe93f81245c529237ffc513 Mon Sep 17 00:00:00 2001 From: Damien Miller Date: Mon, 4 Nov 2013 08:26:52 +1100 Subject: [PATCH] - markus@cvs.openbsd.org 2013/11/02 21:59:15 [kex.c kex.h myproposal.h ssh-keyscan.c sshconnect2.c sshd.c] use curve25519 for default key exchange (curve25519-sha256@libssh.org); initial patch from Aris Adamantiadis; ok djm@ --- ChangeLog | 4 + Makefile.in | 4 +- kex.c | 3 +- kex.h | 19 ++- myproposal.h | 3 +- smult_curve25519_ref.c | 265 +++++++++++++++++++++++++++++++++++++++++ ssh-keyscan.c | 3 +- sshconnect2.c | 3 +- sshd.c | 3 +- 9 files changed, 299 insertions(+), 8 deletions(-) create mode 100644 smult_curve25519_ref.c diff --git a/ChangeLog b/ChangeLog index 75a300584..4c4d8eeb1 100644 --- a/ChangeLog +++ b/ChangeLog @@ -4,6 +4,10 @@ [ssh-pkcs11.c] support pkcs#11 tokes that only provide x509 zerts instead of raw pubkeys; fixes bz#1908; based on patch from Laurent Barbe; ok djm + - markus@cvs.openbsd.org 2013/11/02 21:59:15 + [kex.c kex.h myproposal.h ssh-keyscan.c sshconnect2.c sshd.c] + use curve25519 for default key exchange (curve25519-sha256@libssh.org); + initial patch from Aris Adamantiadis; ok djm@ 20131103 - (dtucker) [openbsd-compat/bsd-misc.c] Include time.h for nanosleep. diff --git a/Makefile.in b/Makefile.in index 92c95a928..797aa3e0c 100644 --- a/Makefile.in +++ b/Makefile.in @@ -1,4 +1,4 @@ -# $Id: Makefile.in,v 1.340 2013/06/11 01:26:10 dtucker Exp $ +# $Id: Makefile.in,v 1.341 2013/11/03 21:26:53 djm Exp $ # uncomment if you run a non bourne compatable shell. Ie. csh #SHELL = @SH@ @@ -73,7 +73,7 @@ LIBSSH_OBJS=authfd.o authfile.o bufaux.o bufbn.o buffer.o \ monitor_fdpass.o rijndael.o ssh-dss.o ssh-ecdsa.o ssh-rsa.o dh.o \ kexdh.o kexgex.o kexdhc.o kexgexc.o bufec.o kexecdh.o kexecdhc.o \ msg.o progressmeter.o dns.o entropy.o gss-genr.o umac.o umac128.o \ - jpake.o schnorr.o ssh-pkcs11.o krl.o + jpake.o schnorr.o ssh-pkcs11.o krl.o smult_curve25519_ref.o SSHOBJS= ssh.o readconf.o clientloop.o sshtty.o \ sshconnect.o sshconnect1.o sshconnect2.o mux.o \ diff --git a/kex.c b/kex.c index 54bd1a438..07f25e2e2 100644 --- a/kex.c +++ b/kex.c @@ -1,4 +1,4 @@ -/* $OpenBSD: kex.c,v 1.91 2013/05/17 00:13:13 djm Exp $ */ +/* $OpenBSD: kex.c,v 1.92 2013/11/02 21:59:15 markus Exp $ */ /* * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. * @@ -80,6 +80,7 @@ static const struct kexalg kexalgs[] = { { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, EVP_sha384 }, { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, EVP_sha512 }, #endif + { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, EVP_sha256 }, { NULL, -1, -1, NULL}, }; diff --git a/kex.h b/kex.h index 9f1e1adb3..0f67f5934 100644 --- a/kex.h +++ b/kex.h @@ -1,4 +1,4 @@ -/* $OpenBSD: kex.h,v 1.56 2013/07/19 07:37:48 markus Exp $ */ +/* $OpenBSD: kex.h,v 1.57 2013/11/02 21:59:15 markus Exp $ */ /* * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. @@ -43,6 +43,7 @@ #define KEX_ECDH_SHA2_NISTP256 "ecdh-sha2-nistp256" #define KEX_ECDH_SHA2_NISTP384 "ecdh-sha2-nistp384" #define KEX_ECDH_SHA2_NISTP521 "ecdh-sha2-nistp521" +#define KEX_CURVE25519_SHA256 "curve25519-sha256@libssh.org" #define COMP_NONE 0 #define COMP_ZLIB 1 @@ -74,6 +75,7 @@ enum kex_exchange { KEX_DH_GEX_SHA1, KEX_DH_GEX_SHA256, KEX_ECDH_SHA2, + KEX_C25519_SHA256, KEX_MAX }; @@ -161,6 +163,8 @@ void kexgex_client(Kex *); void kexgex_server(Kex *); void kexecdh_client(Kex *); void kexecdh_server(Kex *); +void kexc25519_client(Kex *); +void kexc25519_server(Kex *); void kex_dh_hash(char *, char *, char *, int, char *, int, u_char *, int, @@ -175,6 +179,19 @@ kex_ecdh_hash(const EVP_MD *, const EC_GROUP *, char *, char *, char *, int, char *, int, u_char *, int, const EC_POINT *, const EC_POINT *, const BIGNUM *, u_char **, u_int *); #endif +void +kex_c25519_hash(const EVP_MD *, char *, char *, char *, int, + char *, int, u_char *, int, const u_char *, const u_char *, + const BIGNUM *, u_char **, u_int *); + +#define CURVE25519_SIZE 32 +void kexc25519_keygen(u_char[CURVE25519_SIZE], u_char[CURVE25519_SIZE]) + __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) + __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); +BIGNUM *kexc25519_shared_key(const u_char[CURVE25519_SIZE], + const u_char[CURVE25519_SIZE]) + __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) + __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))); void derive_ssh1_session_id(BIGNUM *, BIGNUM *, u_int8_t[8], u_int8_t[16]); diff --git a/myproposal.h b/myproposal.h index 4e913e3ce..0820749a8 100644 --- a/myproposal.h +++ b/myproposal.h @@ -1,4 +1,4 @@ -/* $OpenBSD: myproposal.h,v 1.32 2013/01/08 18:49:04 markus Exp $ */ +/* $OpenBSD: myproposal.h,v 1.33 2013/11/02 21:59:15 markus Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. @@ -66,6 +66,7 @@ #endif # define KEX_DEFAULT_KEX \ + "curve25519-sha256@libssh.org," \ KEX_ECDH_METHODS \ KEX_SHA256_METHODS \ "diffie-hellman-group-exchange-sha1," \ diff --git a/smult_curve25519_ref.c b/smult_curve25519_ref.c new file mode 100644 index 000000000..2e69934d4 --- /dev/null +++ b/smult_curve25519_ref.c @@ -0,0 +1,265 @@ +/* $OpenBSD: smult_curve25519_ref.c,v 1.2 2013/11/02 22:02:14 markus Exp $ */ +/* +version 20081011 +Matthew Dempsky +Public domain. +Derived from public domain code by D. J. Bernstein. +*/ + +int crypto_scalarmult_curve25519(unsigned char *, const unsigned char *, const unsigned char *); + +static void add(unsigned int out[32],const unsigned int a[32],const unsigned int b[32]) +{ + unsigned int j; + unsigned int u; + u = 0; + for (j = 0;j < 31;++j) { u += a[j] + b[j]; out[j] = u & 255; u >>= 8; } + u += a[31] + b[31]; out[31] = u; +} + +static void sub(unsigned int out[32],const unsigned int a[32],const unsigned int b[32]) +{ + unsigned int j; + unsigned int u; + u = 218; + for (j = 0;j < 31;++j) { + u += a[j] + 65280 - b[j]; + out[j] = u & 255; + u >>= 8; + } + u += a[31] - b[31]; + out[31] = u; +} + +static void squeeze(unsigned int a[32]) +{ + unsigned int j; + unsigned int u; + u = 0; + for (j = 0;j < 31;++j) { u += a[j]; a[j] = u & 255; u >>= 8; } + u += a[31]; a[31] = u & 127; + u = 19 * (u >> 7); + for (j = 0;j < 31;++j) { u += a[j]; a[j] = u & 255; u >>= 8; } + u += a[31]; a[31] = u; +} + +static const unsigned int minusp[32] = { + 19, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 128 +} ; + +static void freeze(unsigned int a[32]) +{ + unsigned int aorig[32]; + unsigned int j; + unsigned int negative; + + for (j = 0;j < 32;++j) aorig[j] = a[j]; + add(a,a,minusp); + negative = -((a[31] >> 7) & 1); + for (j = 0;j < 32;++j) a[j] ^= negative & (aorig[j] ^ a[j]); +} + +static void mult(unsigned int out[32],const unsigned int a[32],const unsigned int b[32]) +{ + unsigned int i; + unsigned int j; + unsigned int u; + + for (i = 0;i < 32;++i) { + u = 0; + for (j = 0;j <= i;++j) u += a[j] * b[i - j]; + for (j = i + 1;j < 32;++j) u += 38 * a[j] * b[i + 32 - j]; + out[i] = u; + } + squeeze(out); +} + +static void mult121665(unsigned int out[32],const unsigned int a[32]) +{ + unsigned int j; + unsigned int u; + + u = 0; + for (j = 0;j < 31;++j) { u += 121665 * a[j]; out[j] = u & 255; u >>= 8; } + u += 121665 * a[31]; out[31] = u & 127; + u = 19 * (u >> 7); + for (j = 0;j < 31;++j) { u += out[j]; out[j] = u & 255; u >>= 8; } + u += out[j]; out[j] = u; +} + +static void square(unsigned int out[32],const unsigned int a[32]) +{ + unsigned int i; + unsigned int j; + unsigned int u; + + for (i = 0;i < 32;++i) { + u = 0; + for (j = 0;j < i - j;++j) u += a[j] * a[i - j]; + for (j = i + 1;j < i + 32 - j;++j) u += 38 * a[j] * a[i + 32 - j]; + u *= 2; + if ((i & 1) == 0) { + u += a[i / 2] * a[i / 2]; + u += 38 * a[i / 2 + 16] * a[i / 2 + 16]; + } + out[i] = u; + } + squeeze(out); +} + +static void select(unsigned int p[64],unsigned int q[64],const unsigned int r[64],const unsigned int s[64],unsigned int b) +{ + unsigned int j; + unsigned int t; + unsigned int bminus1; + + bminus1 = b - 1; + for (j = 0;j < 64;++j) { + t = bminus1 & (r[j] ^ s[j]); + p[j] = s[j] ^ t; + q[j] = r[j] ^ t; + } +} + +static void mainloop(unsigned int work[64],const unsigned char e[32]) +{ + unsigned int xzm1[64]; + unsigned int xzm[64]; + unsigned int xzmb[64]; + unsigned int xzm1b[64]; + unsigned int xznb[64]; + unsigned int xzn1b[64]; + unsigned int a0[64]; + unsigned int a1[64]; + unsigned int b0[64]; + unsigned int b1[64]; + unsigned int c1[64]; + unsigned int r[32]; + unsigned int s[32]; + unsigned int t[32]; + unsigned int u[32]; + unsigned int j; + unsigned int b; + int pos; + + for (j = 0;j < 32;++j) xzm1[j] = work[j]; + xzm1[32] = 1; + for (j = 33;j < 64;++j) xzm1[j] = 0; + + xzm[0] = 1; + for (j = 1;j < 64;++j) xzm[j] = 0; + + for (pos = 254;pos >= 0;--pos) { + b = e[pos / 8] >> (pos & 7); + b &= 1; + select(xzmb,xzm1b,xzm,xzm1,b); + add(a0,xzmb,xzmb + 32); + sub(a0 + 32,xzmb,xzmb + 32); + add(a1,xzm1b,xzm1b + 32); + sub(a1 + 32,xzm1b,xzm1b + 32); + square(b0,a0); + square(b0 + 32,a0 + 32); + mult(b1,a1,a0 + 32); + mult(b1 + 32,a1 + 32,a0); + add(c1,b1,b1 + 32); + sub(c1 + 32,b1,b1 + 32); + square(r,c1 + 32); + sub(s,b0,b0 + 32); + mult121665(t,s); + add(u,t,b0); + mult(xznb,b0,b0 + 32); + mult(xznb + 32,s,u); + square(xzn1b,c1); + mult(xzn1b + 32,r,work); + select(xzm,xzm1,xznb,xzn1b,b); + } + + for (j = 0;j < 64;++j) work[j] = xzm[j]; +} + +static void recip(unsigned int out[32],const unsigned int z[32]) +{ + unsigned int z2[32]; + unsigned int z9[32]; + unsigned int z11[32]; + unsigned int z2_5_0[32]; + unsigned int z2_10_0[32]; + unsigned int z2_20_0[32]; + unsigned int z2_50_0[32]; + unsigned int z2_100_0[32]; + unsigned int t0[32]; + unsigned int t1[32]; + int i; + + /* 2 */ square(z2,z); + /* 4 */ square(t1,z2); + /* 8 */ square(t0,t1); + /* 9 */ mult(z9,t0,z); + /* 11 */ mult(z11,z9,z2); + /* 22 */ square(t0,z11); + /* 2^5 - 2^0 = 31 */ mult(z2_5_0,t0,z9); + + /* 2^6 - 2^1 */ square(t0,z2_5_0); + /* 2^7 - 2^2 */ square(t1,t0); + /* 2^8 - 2^3 */ square(t0,t1); + /* 2^9 - 2^4 */ square(t1,t0); + /* 2^10 - 2^5 */ square(t0,t1); + /* 2^10 - 2^0 */ mult(z2_10_0,t0,z2_5_0); + + /* 2^11 - 2^1 */ square(t0,z2_10_0); + /* 2^12 - 2^2 */ square(t1,t0); + /* 2^20 - 2^10 */ for (i = 2;i < 10;i += 2) { square(t0,t1); square(t1,t0); } + /* 2^20 - 2^0 */ mult(z2_20_0,t1,z2_10_0); + + /* 2^21 - 2^1 */ square(t0,z2_20_0); + /* 2^22 - 2^2 */ square(t1,t0); + /* 2^40 - 2^20 */ for (i = 2;i < 20;i += 2) { square(t0,t1); square(t1,t0); } + /* 2^40 - 2^0 */ mult(t0,t1,z2_20_0); + + /* 2^41 - 2^1 */ square(t1,t0); + /* 2^42 - 2^2 */ square(t0,t1); + /* 2^50 - 2^10 */ for (i = 2;i < 10;i += 2) { square(t1,t0); square(t0,t1); } + /* 2^50 - 2^0 */ mult(z2_50_0,t0,z2_10_0); + + /* 2^51 - 2^1 */ square(t0,z2_50_0); + /* 2^52 - 2^2 */ square(t1,t0); + /* 2^100 - 2^50 */ for (i = 2;i < 50;i += 2) { square(t0,t1); square(t1,t0); } + /* 2^100 - 2^0 */ mult(z2_100_0,t1,z2_50_0); + + /* 2^101 - 2^1 */ square(t1,z2_100_0); + /* 2^102 - 2^2 */ square(t0,t1); + /* 2^200 - 2^100 */ for (i = 2;i < 100;i += 2) { square(t1,t0); square(t0,t1); } + /* 2^200 - 2^0 */ mult(t1,t0,z2_100_0); + + /* 2^201 - 2^1 */ square(t0,t1); + /* 2^202 - 2^2 */ square(t1,t0); + /* 2^250 - 2^50 */ for (i = 2;i < 50;i += 2) { square(t0,t1); square(t1,t0); } + /* 2^250 - 2^0 */ mult(t0,t1,z2_50_0); + + /* 2^251 - 2^1 */ square(t1,t0); + /* 2^252 - 2^2 */ square(t0,t1); + /* 2^253 - 2^3 */ square(t1,t0); + /* 2^254 - 2^4 */ square(t0,t1); + /* 2^255 - 2^5 */ square(t1,t0); + /* 2^255 - 21 */ mult(out,t1,z11); +} + +int crypto_scalarmult_curve25519(unsigned char *q, + const unsigned char *n, + const unsigned char *p) +{ + unsigned int work[96]; + unsigned char e[32]; + unsigned int i; + for (i = 0;i < 32;++i) e[i] = n[i]; + e[0] &= 248; + e[31] &= 127; + e[31] |= 64; + for (i = 0;i < 32;++i) work[i] = p[i]; + mainloop(work,e); + recip(work + 32,work + 32); + mult(work + 64,work,work + 32); + freeze(work + 64); + for (i = 0;i < 32;++i) q[i] = work[64 + i]; + return 0; +} diff --git a/ssh-keyscan.c b/ssh-keyscan.c index 8b807c10a..c5f658d77 100644 --- a/ssh-keyscan.c +++ b/ssh-keyscan.c @@ -1,4 +1,4 @@ -/* $OpenBSD: ssh-keyscan.c,v 1.87 2013/05/17 00:13:14 djm Exp $ */ +/* $OpenBSD: ssh-keyscan.c,v 1.88 2013/11/02 21:59:15 markus Exp $ */ /* * Copyright 1995, 1996 by David Mazieres . * @@ -254,6 +254,7 @@ keygrab_ssh2(con *c) c->c_kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; c->c_kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; c->c_kex->kex[KEX_ECDH_SHA2] = kexecdh_client; + c->c_kex->kex[KEX_C25519_SHA256] = kexc25519_client; c->c_kex->verify_host_key = hostjump; if (!(j = setjmp(kexjmp))) { diff --git a/sshconnect2.c b/sshconnect2.c index 70e3cd8c9..1f6160e86 100644 --- a/sshconnect2.c +++ b/sshconnect2.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshconnect2.c,v 1.198 2013/06/05 12:52:38 dtucker Exp $ */ +/* $OpenBSD: sshconnect2.c,v 1.199 2013/11/02 21:59:15 markus Exp $ */ /* * Copyright (c) 2000 Markus Friedl. All rights reserved. * Copyright (c) 2008 Damien Miller. All rights reserved. @@ -208,6 +208,7 @@ ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port) kex->kex[KEX_DH_GEX_SHA1] = kexgex_client; kex->kex[KEX_DH_GEX_SHA256] = kexgex_client; kex->kex[KEX_ECDH_SHA2] = kexecdh_client; + kex->kex[KEX_C25519_SHA256] = kexc25519_client; kex->client_version_string=client_version_string; kex->server_version_string=server_version_string; kex->verify_host_key=&verify_host_key_callback; diff --git a/sshd.c b/sshd.c index d4349f618..8a62fc1a6 100644 --- a/sshd.c +++ b/sshd.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshd.c,v 1.409 2013/10/23 23:35:32 djm Exp $ */ +/* $OpenBSD: sshd.c,v 1.410 2013/11/02 21:59:15 markus Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -2451,6 +2451,7 @@ do_ssh2_kex(void) kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; kex->kex[KEX_ECDH_SHA2] = kexecdh_server; + kex->kex[KEX_C25519_SHA256] = kexc25519_server; kex->server = 1; kex->client_version_string=client_version_string; kex->server_version_string=server_version_string;