Mercurial > dropbear

changeset 756:bf9dc2d9c2b1 ecc

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more bits on ecc branch
author Matt Johnston <matt@ucc.asn.au>
date Wed, 27 Mar 2013 00:38:03 +0800
parents b07eb3dc23ec
children 230666086711
files Makefile.in algo.h cli-kex.c common-algo.c common-kex.c ecc.c ecc.h kex.h libtomcrypt/src/headers/tomcrypt_custom.h session.h sysoptions.h
diffstat 11 files changed, 281 insertions(+), 25 deletions(-) [+]
line wrap: on
line diff
--- a/Makefile.in	Tue Mar 26 01:35:22 2013 +0800
+++ b/Makefile.in	Wed Mar 27 00:38:03 2013 +0800
@@ -26,7 +26,7 @@
 		dss.o bignum.o \
 		signkey.o rsa.o random.o \
 		queue.o \
-		atomicio.o compat.o  fake-rfc2553.o ltc_prng.o ecc.o
+		atomicio.o compat.o fake-rfc2553.o ltc_prng.o ecc.o
 
 SVROBJS=svr-kex.o svr-algo.o svr-auth.o sshpty.o \
 		svr-authpasswd.o svr-authpubkey.o svr-authpubkeyoptions.o svr-session.o svr-service.o \
--- a/algo.h	Tue Mar 26 01:35:22 2013 +0800
+++ b/algo.h	Wed Mar 27 00:38:03 2013 +0800
@@ -79,6 +79,20 @@
 	unsigned char hashsize;
 };
 
+struct dropbear_kex {
+	// "normal" DH KEX
+	unsigned char *dh_p_bytes;
+	int dh_p_len;
+
+	// elliptic curve DH KEX
+#ifdef DROPBEAR_ECDH
+	const struct dropbear_ecc_curve *ecc_curve;
+#endif
+
+	// both
+	const struct ltc_hash_descriptor *hashdesc;
+};
+
 void crypto_init();
 int have_algo(char* algo, size_t algolen, algo_type algos[]);
 void buf_put_algolist(buffer * buf, algo_type localalgos[]);
@@ -94,14 +108,16 @@
 char * algolist_string(algo_type algos[]);
 #endif
 
-enum {
+enum kex_type {
 	DROPBEAR_KEX_DH_GROUP1,
 	DROPBEAR_KEX_DH_GROUP14,
 	DROPBEAR_KEX_ECDH_SECP256R1,
+	DROPBEAR_KEX_ECDH_SECP384R1,
+	DROPBEAR_KEX_ECDH_SECP521R1,
 };
 
 #ifdef DROPBEAR_ECDH
-#define IS_NORMAL_DH(algo) ((algo) == DROPBEAR_KEX_DH_GROUP1 || (algo) == DROPBEAR_KEX_DH_GROUP14)
+#define IS_NORMAL_DH(algo) ((algo)->dh_p_bytes != NULL)
 #else
 #define IS_NORMAL_DH(algo) 1
 #endif
--- a/cli-kex.c	Tue Mar 26 01:35:22 2013 +0800
+++ b/cli-kex.c	Wed Mar 27 00:38:03 2013 +0800
@@ -49,7 +49,7 @@
 		buf_putmpint(ses.writepayload, &cli_ses.dh_param->pub);
 	} else {
 #ifdef DROPBEAR_ECDH
-		cli_ses.ecdh_param = 
+		cli_ses.ecdh_param = gen_kexecdh_param();
 #endif
 	}
 	encrypt_packet();
--- a/common-algo.c	Tue Mar 26 01:35:22 2013 +0800
+++ b/common-algo.c	Wed Mar 27 00:38:03 2013 +0800
@@ -212,10 +212,36 @@
 	{NULL, 0, NULL, 0, NULL}
 };
 
+static struct dropbear_kex kex_dh_group1 {dh_p_1, DH_P_1_LEN, NULL, sha1_desc };
+static struct dropbear_kex kex_dh_group14 {dh_p_14, DH_P_14_LEN, NULL, sha1_desc };
+
+#ifdef DROPBEAR_ECC_DH
+#ifdef DROPBEAR_ECC_256
+static struct dropbear_kex kex_ecdh_secp256r1 {NULL, 0, &ecc_curve_secp256r1, sha256_desc };
+#endif
+#ifdef DROPBEAR_ECC_384
+static struct dropbear_kex kex_ecdh_secp384r1 {NULL, 0, &ecc_curve_secp384r1, sha384_desc };
+#endif
+#ifdef DROPBEAR_ECC_521
+static struct dropbear_kex kex_ecdh_secp521r1 {NULL, 0, &ecc_curve_secp521r1, sha512_desc };
+#endif
+#endif // DROPBEAR_ECC_DH
+
+
 algo_type sshkex[] = {
-//	{"ecdh-sha2-secp256r1", DROPBEAR_KEX_ECDH_SECP256R1, NULL, 1, NULL},
-	{"diffie-hellman-group1-sha1", DROPBEAR_KEX_DH_GROUP1, NULL, 1, NULL},
-	{"diffie-hellman-group14-sha1", DROPBEAR_KEX_DH_GROUP14, NULL, 1, NULL},
+#ifdef DROPBEAR_ECC_DH
+#ifdef DROPBEAR_ECC_256
+	{"ecdh-sha2-secp256r1", 0, &kex_ecdh_descp256r1, 1, NULL},
+#endif
+#ifdef DROPBEAR_ECC_384
+	{"ecdh-sha2-secp384r1", 0, &kex_ecdh_descp384r1, 1, NULL},
+#endif
+#ifdef DROPBEAR_ECC_521
+	{"ecdh-sha2-secp521r1", 0, &kex_ecdh_descp521r1, 1, NULL},
+#endif
+#endif
+	{"diffie-hellman-group1-sha1", 0, &kex_dh_group1, 1, NULL},
+	{"diffie-hellman-group14-sha1", 0, &kex_dh_group14, 1, NULL},
 	{NULL, 0, NULL, 0, NULL}
 };
 
--- a/common-kex.c	Tue Mar 26 01:35:22 2013 +0800
+++ b/common-kex.c	Wed Mar 27 00:38:03 2013 +0800
@@ -36,8 +36,7 @@
 #include "runopts.h"
 
 /* diffie-hellman-group1-sha1 value for p */
-#define DH_P_1_LEN 128
-static const unsigned char dh_p_1[DH_P_1_LEN] = {
+const unsigned char dh_p_1[DH_P_1_LEN] = {
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
     0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
 	0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
@@ -51,8 +50,7 @@
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
 
 /* diffie-hellman-group14-sha1 value for p */
-#define DH_P_14_LEN 256
-static const unsigned char dh_p_14[DH_P_14_LEN] = {
+const unsigned char dh_p_14[DH_P_14_LEN] = {
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2, 
     0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1, 
 	0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
@@ -536,14 +534,8 @@
 
 static void load_dh_p(mp_int * dh_p)
 {
-	switch (ses.newkeys->algo_kex) {
-		case DROPBEAR_KEX_DH_GROUP1:
-			bytes_to_mp(dh_p, dh_p_1, DH_P_1_LEN);
-			break;
-		case DROPBEAR_KEX_DH_GROUP14:
-			bytes_to_mp(dh_p, dh_p_14, DH_P_14_LEN);
-			break;
-	}
+	bytes_to_mp(dh_p, ses.newkeys->algo_kex->dh_p_bytes, 
+		ses.newkeys->algo_kex->dh_p_len);
 }
 
 /* Initialises and generate one side of the diffie-hellman key exchange values.
@@ -667,11 +659,84 @@
 #ifdef DROPBEAR_ECDH
 struct kex_ecdh_param *gen_kexecdh_param() {
 	struct kex_ecdh_param *param = m_malloc(sizeof(*param));
-	if (ecc_make_key_ex(NULL, dropbear_ltc_prng, &param->key
+	if (ecc_make_key_ex(NULL, dropbear_ltc_prng, 
+		&param->key, ses.newkeys->algo_kex->ecc_curve) != CRYPT_OK) {
+		dropbear_exit("ECC error")
+	}
+	return param;
+}
+
+void free_kexecdh_param(struct kex_ecdh_param *param) {
+	ecc_free(&param->key);
+	m_free(param);
+
 }
-void free_kexecdh_param(struct kex_ecdh_param *param);
 void kexecdh_comb_key(struct kex_ecdh_param *param, buffer *pub_them,
-		sign_key *hostkey);
+		sign_key *hostkey) {
+
+	hash_state hs;
+	// public keys from client and server
+	ecc_key *Q_C, *Q_S, *Q_them;
+
+	// XXX load Q_them
+
+	ses.dh_K = dropbear_ecc_shared_secret()
+	
+	/* Check that dh_pub_them (dh_e or dh_f) is in the range [1, p-1] */
+	if (mp_cmp(dh_pub_them, &dh_p) != MP_LT 
+			|| mp_cmp_d(dh_pub_them, 0) != MP_GT) {
+		dropbear_exit("Diffie-Hellman error");
+	}
+	
+	/* K = e^y mod p = f^x mod p */
+	ses.dh_K = (mp_int*)m_malloc(sizeof(mp_int));
+	m_mp_init(ses.dh_K);
+	if (mp_exptmod(dh_pub_them, &param->priv, &dh_p, ses.dh_K) != MP_OKAY) {
+		dropbear_exit("Diffie-Hellman error");
+	}
+
+	/* clear no longer needed vars */
+	mp_clear_multi(&dh_p, NULL);
+
+	/* From here on, the code needs to work with the _same_ vars on each side,
+	 * not vice-versaing for client/server */
+	if (IS_DROPBEAR_CLIENT) {
+		dh_e = &param->pub;
+		dh_f = dh_pub_them;
+	} else {
+		dh_e = dh_pub_them;
+		dh_f = &param->pub;
+	} 
+
+	/* Create the remainder of the hash buffer, to generate the exchange hash */
+	/* K_S, the host key */
+	buf_put_pub_key(ses.kexhashbuf, hostkey, ses.newkeys->algo_hostkey);
+	/* e, exchange value sent by the client */
+	buf_putmpint(ses.kexhashbuf, dh_e);
+	/* f, exchange value sent by the server */
+	buf_putmpint(ses.kexhashbuf, dh_f);
+	/* K, the shared secret */
+	buf_putmpint(ses.kexhashbuf, ses.dh_K);
+
+	/* calculate the hash H to sign */
+	sha1_init(&hs);
+	buf_setpos(ses.kexhashbuf, 0);
+	sha1_process(&hs, buf_getptr(ses.kexhashbuf, ses.kexhashbuf->len),
+			ses.kexhashbuf->len);
+	sha1_done(&hs, ses.hash);
+
+	buf_burn(ses.kexhashbuf);
+	buf_free(ses.kexhashbuf);
+	ses.kexhashbuf = NULL;
+	
+	/* first time around, we set the session_id to H */
+	if (ses.session_id == NULL) {
+		/* create the session_id, this never needs freeing */
+		ses.session_id = (unsigned char*)m_malloc(SHA1_HASH_SIZE);
+		memcpy(ses.session_id, ses.hash, SHA1_HASH_SIZE);
+	}
+
+}
 #endif
 
 /* read the other side's algo list. buf_match_algo is a callback to match
@@ -707,7 +772,7 @@
 		goto error;
 	}
 	TRACE(("kex algo %s", algo->name))
-	ses.newkeys->algo_kex = algo->val;
+	ses.newkeys->algo_kex = algo->data;
 
 	/* server_host_key_algorithms */
 	algo = ses.buf_match_algo(ses.payload, sshhostkey, &goodguess);
--- a/ecc.c	Tue Mar 26 01:35:22 2013 +0800
+++ b/ecc.c	Wed Mar 27 00:38:03 2013 +0800
@@ -1,6 +1,37 @@
+#include "includes.h"
+#include "options.h"
+#include "ecc.h"
+
 #ifdef DROPBEAR_ECC
 
+#ifdef DROPBEAR_ECC_256
+const struct ecc_curve_secp256r1 {
+	.ltc_set = &ltc_ecc_sets[0],
+	.hash_desc = sha256_desc,
+	.name = "secp256r1"
+};
+#endif
+
+
+#ifdef DROPBEAR_ECC_384
+const struct ecc_curve_secp384r1 {
+	.ltc_set = &ltc_ecc_sets[1],
+	.hash_desc = sha384_desc,
+	.name = "secp384r1"
+};
+#endif
+
+#ifdef DROPBEAR_ECC_256
+const struct ecc_curve_secp256r1 {
+	.ltc_set = &ltc_ecc_sets[0],
+	.hash_desc = sha256_desc,
+	.name = "secp256r1"
+};
+#endif
+
+
 void buf_put_ecc_key_string(buffer *buf, ecc_key *key) {
+	// XXX point compression
 	int len = key->dp->size*2 + 1;
 	buf_putint(len);
 	int err = ecc_ansi_x963_export(key, buf_getwriteptr(buf, len), &len);
@@ -13,5 +44,71 @@
 int buf_get_ecc_key_string(buffer *buf, ecc_key *key) {
 }
 
+// a modified version of libtomcrypt's "ecc_shared_secret" to output
+// a mp_int instead.
+mp_int * dropbear_ecc_shared_secret(ecc_key *public_key, ecc_key *private_key)
+{
+   ecc_point *result = NULL
+   mp_int *prime = NULL, *shared_secret = NULL;
+   int ret = DROPBEAR_FAILURE;
+
+   /* type valid? */
+   if (private_key->type != PK_PRIVATE) {
+   	goto done;
+   }
+
+   if (private_key->dp != public_key->dp) {
+   	goto done;
+   }
+
+#if 0
+   // XXX - possibly not neccessary tests?
+   if (ltc_ecc_is_valid_idx(private_key->idx) == 0 || ltc_ecc_is_valid_idx(public_key->idx) == 0) {
+   	goto done;
+   }
+
+   if (XSTRCMP(private_key->dp->name, public_key->dp->name) != 0) {
+   	goto done;
+   }
+#endif
+
+   /* make new point */
+   result = ltc_ecc_new_point();
+   if (result == NULL) {
+      goto done;
+   }
+
+   prime = m_malloc(sizeof(*prime));
+   m_mp_init(prime);
+
+   if (mp_read_radix(prime, (char *)private_key->dp->prime, 16) != CRYPT_OK) { 
+	   	goto done; 
+   }
+   if (ltc_mp.ecc_ptmul(private_key->k, &public_key->pubkey, result, prime, 1) != CRYPT_OK) { 
+	   	goto done; 
+   }
+
+   err = DROPBEAR_SUCCESS;
+done:
+	if (err == DROPBEAR_SUCCESS) {
+		shared_secret = prime;
+		prime = NULL;
+	}
+
+	if (prime) {
+	   mp_clear(prime);
+	   m_free(prime);
+	}
+   ltc_ecc_del_point(result);
+
+   if (err == DROPBEAR_FAILURE) {
+   	 dropbear_exit("ECC error");
+   }
+
+   return shared_secret;
+   return err;
+}
+
+}
 
 #endif
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ecc.h	Wed Mar 27 00:38:03 2013 +0800
@@ -0,0 +1,34 @@
+#ifndef _DROPBEAR_ECC_H
+#define _DROPBEAR_ECC_H
+
+#include "includes.h"
+#include "options.h"
+
+#include "buffer.h"
+
+#ifdef DROPBEAR_ECC
+
+struct dropbear_ecc_curve {
+	const ltc_ecc_set_type* ltc_set;
+	const struct ltc_hash_descriptor *hash_desc;
+	const char *name;
+};
+
+extern const struct dropbear_ecc_curve ecc_curve_secp256r1;
+extern const struct dropbear_ecc_curve ecc_curve_secp384r1;
+extern const struct dropbear_ecc_curve ecc_curve_secp521r1;
+
+// "pubkey" refers to a point, but LTC uses ecc_key structure for both public
+// and private keys
+void buf_put_ecc_pubkey_string(buffer *buf, ecc_key *key);
+int buf_get_ecc_pubkey_string(buffer *buf, ecc_key *key);
+int buf_get_ecc_privkey_string(buffer *buf, ecc_key *key);
+
+mp_int * dropbear_ecc_shared_secret(ecc_key *pub_key, ecc_key *priv_key);
+
+
+const ltc_ecc_set_type* get_ecc_curve(enum kex_type type);
+
+#endif
+
+#endif // _DROPBEAR_ECC_H
\ No newline at end of file
--- a/kex.h	Tue Mar 26 01:35:22 2013 +0800
+++ b/kex.h	Wed Mar 27 00:38:03 2013 +0800
@@ -73,6 +73,11 @@
 
 };
 
+#define DH_P_1_LEN 128
+extern const const unsigned char dh_p_1[DH_P_1_LEN];
+#define DH_P_14_LEN 256
+const unsigned char dh_p_14[DH_P_14_LEN] = {
+
 struct kex_dh_param {
 	mp_int pub;
 	mp_int priv;
--- a/libtomcrypt/src/headers/tomcrypt_custom.h	Tue Mar 26 01:35:22 2013 +0800
+++ b/libtomcrypt/src/headers/tomcrypt_custom.h	Wed Mar 27 00:38:03 2013 +0800
@@ -134,12 +134,18 @@
 
 #define LTC_HMAC
 
-#ifdef DROPBEAR_ECDH
+#ifdef DROPBEAR_ECC
 #define MECC
+#ifdef DROPBEAR_ECC_256
 #define ECC256
+#endif
+#ifdef DROPBEAR_ECC_384
 #define ECC384
+#endif
+#ifdef DROPBEAR_ECC_521
 #define ECC521
 #endif
+#endif
 
 /* Various tidbits of modern neatoness */
 #define BASE64
--- a/session.h	Tue Mar 26 01:35:22 2013 +0800
+++ b/session.h	Wed Mar 27 00:38:03 2013 +0800
@@ -86,7 +86,7 @@
 	struct key_context_directional recv;
 	struct key_context_directional trans;
 
-	int algo_kex;
+	const struct dropbear_kex *algo_kex;
 	int algo_hostkey;
 
 	int allow_compress; /* whether compression has started (useful in 
--- a/sysoptions.h	Tue Mar 26 01:35:22 2013 +0800
+++ b/sysoptions.h	Wed Mar 27 00:38:03 2013 +0800
@@ -93,6 +93,13 @@
 #define DROPBEAR_ECC
 #endif
 
+
+#ifdef DROPBEAR_ECC
+#define DROPBEAR_ECC_256
+#define DROPBEAR_ECC_384
+#define DROPBEAR_ECC_521
+#endif
+
 // roughly 2x 521 bits
 #define MAX_ECC_SIZE 140