diff --git a/cli-auth.c b/cli-auth.c
index cfcf1344315a92c9fb71f8cbc4aa2abfff838943..b4baf9fd51f5ff10daa86ca2b2494b7db901969d 100644
--- a/cli-auth.c
+++ b/cli-auth.c
@@ -257,7 +257,10 @@ void cli_auth_try() {
#endif
#ifdef ENABLE_CLI_INTERACT_AUTH
- if (!finished && ses.authstate.authtypes & AUTH_TYPE_INTERACT) {
+ if (ses.keys->trans.algo_crypt->cipherdesc == NULL) {
+ fprintf(stderr, "Sorry, I won't let you use interactive auth unencrypted.\n");
+ }
+ else if (!finished && ses.authstate.authtypes & AUTH_TYPE_INTERACT) {
if (cli_ses.auth_interact_failed) {
finished = 0;
} else {
@@ -269,7 +272,10 @@ void cli_auth_try() {
#endif
#ifdef ENABLE_CLI_PASSWORD_AUTH
- if (!finished && ses.authstate.authtypes & AUTH_TYPE_PASSWORD) {
+ if (ses.keys->trans.algo_crypt->cipherdesc == NULL) {
+ fprintf(stderr, "Sorry, I won't let you use password auth unencrypted.\n");
+ }
+ else if (!finished && ses.authstate.authtypes & AUTH_TYPE_PASSWORD) {
cli_auth_password();
finished = 1;
cli_ses.lastauthtype = AUTH_TYPE_PASSWORD;
diff --git a/common-algo.c b/common-algo.c
index e65bd183574456312b45c5589c92446d72f70c74..4383bcaf84e6b662a7b9b9f68e0222cf155698a8 100644
--- a/common-algo.c
+++ b/common-algo.c
@@ -159,6 +159,9 @@ algo_type sshciphers[] = {
#endif
#ifdef DROPBEAR_BLOWFISH
{"blowfish-cbc", 0, &dropbear_blowfish, 1, &dropbear_mode_cbc},
+#endif
+#ifdef DROPBEAR_NONE_CIPHER
+ {"none", 0, (void*)&dropbear_nocipher, 1, &dropbear_mode_none},
#endif
{NULL, 0, NULL, 0, NULL}
};
@@ -177,7 +180,10 @@ algo_type sshhashes[] = {
{"hmac-sha1", 0, &dropbear_sha1, 1, NULL},
#endif
#ifdef DROPBEAR_MD5_HMAC
- {"hmac-md5", 0, &dropbear_md5, 1, NULL},
+ {"hmac-md5", 0, (void*)&dropbear_md5, 1, NULL},
+#endif
+#ifdef DROPBEAR_NONE_INTEGRITY
+ {"none", 0, (void*)&dropbear_nohash, 1, NULL},
#endif
{NULL, 0, NULL, 0, NULL}
};
diff --git a/common-kex.c b/common-kex.c
index c53fdf847b749a388db6e097c7bca1c123e562c5..bf39ca973219b24f8d45c68631fbd1060ee33362 100644
--- a/common-kex.c
+++ b/common-kex.c
@@ -293,7 +293,6 @@ void gen_new_keys() {
hash_state hs;
unsigned int C2S_keysize, S2C_keysize;
char mactransletter, macrecvletter; /* Client or server specific */
- int recv_cipher = 0, trans_cipher = 0;
TRACE(("enter gen_new_keys"))
/* the dh_K and hash are the start of all hashes, we make use of that */
@@ -330,31 +329,39 @@ void gen_new_keys() {
hashkeys(C2S_key, C2S_keysize, &hs, 'C');
hashkeys(S2C_key, S2C_keysize, &hs, 'D');
- recv_cipher = find_cipher(ses.newkeys->recv.algo_crypt->cipherdesc->name);
- if (recv_cipher < 0)
- dropbear_exit("Crypto error");
- if (ses.newkeys->recv.crypt_mode->start(recv_cipher,
- recv_IV, recv_key,
- ses.newkeys->recv.algo_crypt->keysize, 0,
- &ses.newkeys->recv.cipher_state) != CRYPT_OK) {
- dropbear_exit("Crypto error");
- }
-
- trans_cipher = find_cipher(ses.newkeys->trans.algo_crypt->cipherdesc->name);
- if (trans_cipher < 0)
- dropbear_exit("Crypto error");
- if (ses.newkeys->trans.crypt_mode->start(trans_cipher,
- trans_IV, trans_key,
- ses.newkeys->trans.algo_crypt->keysize, 0,
- &ses.newkeys->trans.cipher_state) != CRYPT_OK) {
- dropbear_exit("Crypto error");
+ if (ses.newkeys->recv.algo_crypt->cipherdesc != NULL) {
+ int recv_cipher = find_cipher(ses.newkeys->recv.algo_crypt->cipherdesc->name);
+ if (recv_cipher < 0)
+ dropbear_exit("Crypto error");
+ if (ses.newkeys->recv.crypt_mode->start(recv_cipher,
+ recv_IV, recv_key,
+ ses.newkeys->recv.algo_crypt->keysize, 0,
+ &ses.newkeys->recv.cipher_state) != CRYPT_OK) {
+ dropbear_exit("Crypto error");
+ }
}
-
+
+ if (ses.newkeys->trans.algo_crypt->cipherdesc != NULL) {
+ int trans_cipher = find_cipher(ses.newkeys->trans.algo_crypt->cipherdesc->name);
+ if (trans_cipher < 0)
+ dropbear_exit("Crypto error");
+ if (ses.newkeys->trans.crypt_mode->start(trans_cipher,
+ trans_IV, trans_key,
+ ses.newkeys->trans.algo_crypt->keysize, 0,
+ &ses.newkeys->trans.cipher_state) != CRYPT_OK) {
+ dropbear_exit("Crypto error");
+ }
+ }
+
/* MAC keys */
- hashkeys(ses.newkeys->trans.mackey,
- ses.newkeys->trans.algo_mac->keysize, &hs, mactransletter);
- hashkeys(ses.newkeys->recv.mackey,
- ses.newkeys->recv.algo_mac->keysize, &hs, macrecvletter);
+ if (ses.newkeys->trans.algo_mac->hashdesc != NULL) {
+ hashkeys(ses.newkeys->trans.mackey,
+ ses.newkeys->trans.algo_mac->keysize, &hs, mactransletter);
+ }
+ if (ses.newkeys->recv.algo_mac->hashdesc != NULL) {
+ hashkeys(ses.newkeys->recv.mackey,
+ ses.newkeys->recv.algo_mac->keysize, &hs, macrecvletter);
+ }
ses.newkeys->trans.hash_index = find_hash(ses.newkeys->trans.algo_mac->hashdesc->name),
ses.newkeys->recv.hash_index = find_hash(ses.newkeys->recv.algo_mac->hashdesc->name),
diff --git a/options.h b/options.h
index a2848a53f2d4bd48865b5f91912da2e0e63d15af..2350b6b1caf8067741cd9cd270ad29521c018b19 100644
--- a/options.h
+++ b/options.h
@@ -97,6 +97,18 @@ much traffic. */
* size and is recommended for most cases */
#define DROPBEAR_ENABLE_CTR_MODE
+/* You can compile with no encryption if you want. In some circumstances
+ * this could be safe security-wise, though make sure you know what
+ * you're doing. Anyone can see everything that goes over the wire, so
+ * the only safe auth method is public key. You'll have to disable all other
+ * ciphers above in the client if you want to use this, or implement cipher
+ * prioritisation in cli-runopts.
+ *
+ * The best way to do things is probably make normal compile of dropbear with
+ * all ciphers including "none" as the server, then recompile a special
+ * "dbclient-insecure" client. */
+/* #define DROPBEAR_NONE_CIPHER */
+
/* Message Integrity - at least one required.
* Protocol RFC requires sha1 and recommends sha1-96.
* sha1-96 is of use for slow links as it has a smaller overhead.
@@ -109,13 +121,19 @@ much traffic. */
* These hashes are also used for public key fingerprints in logs.
* If you disable MD5, Dropbear will fall back to SHA1 fingerprints,
* which are not the standard form. */
-
#define DROPBEAR_SHA1_HMAC
#define DROPBEAR_SHA1_96_HMAC
/*#define DROPBEAR_SHA2_256_HMAC*/
/*#define DROPBEAR_SHA2_512_HMAC*/
#define DROPBEAR_MD5_HMAC
+/* You can also disable integrity. Don't bother disabling this if you're
+ * still using a cipher, it's relatively cheap. If you disable this it's dead
+ * simple to run arbitrary commands on the remote host. Beware.
+ * Note again, for the client you will have to disable other hashes above
+ * to use this. */
+/* #define DROPBEAR_NONE_INTEGRITY */
+
/* Hostkey/public key algorithms - at least one required, these are used
* for hostkey as well as for verifying signatures with pubkey auth.
* Removing either of these won't save very much space.