Get rid of group15, move group16 to sha512.

New groups are disabled by default pending
draft-ietf-curdle-ssh-kex-sha2-02 being finalised

5 files changed, 37 insertions, 60 deletions

diff --git a/common-algo.c b/common-algo.c
index 1841d67..c2cef77 100644
--- a/common-algo.c
+++ b/common-algo.c
@@ -248,14 +248,17 @@ algo_type sshhostkey[] = {
 	{NULL, 0, NULL, 0, NULL}
 };
 
+#if DROPBEAR_DH_GROUP1
 static const struct dropbear_kex kex_dh_group1 = {DROPBEAR_KEX_NORMAL_DH, dh_p_1, DH_P_1_LEN, NULL, &sha1_desc };
+#endif
+#if DROPBEAR_DH_GROUP14
 static const struct dropbear_kex kex_dh_group14_sha1 = {DROPBEAR_KEX_NORMAL_DH, dh_p_14, DH_P_14_LEN, NULL, &sha1_desc };
+#if DROPBEAR_DH_GROUP14_256
 static const struct dropbear_kex kex_dh_group14_sha256 = {DROPBEAR_KEX_NORMAL_DH, dh_p_14, DH_P_14_LEN, NULL, &sha256_desc };
-#ifdef DROPBEAR_DH_GROUP15
-static const struct dropbear_kex kex_dh_group15_sha256 = {DROPBEAR_KEX_NORMAL_DH, dh_p_15, DH_P_15_LEN, NULL, &sha256_desc };
 #endif
-#ifdef DROPBEAR_DH_GROUP16
-static const struct dropbear_kex kex_dh_group16_sha256 = {DROPBEAR_KEX_NORMAL_DH, dh_p_16, DH_P_16_LEN, NULL, &sha256_desc };
+#endif
+#if DROPBEAR_DH_GROUP16
+static const struct dropbear_kex kex_dh_group16_sha512 = {DROPBEAR_KEX_NORMAL_DH, dh_p_16, DH_P_16_LEN, NULL, &sha512_desc };
 #endif
 
 /* These can't be const since dropbear_ecc_fill_dp() fills out
@@ -292,14 +295,17 @@ algo_type sshkex[] = {
 	{"ecdh-sha2-nistp256", 0, &kex_ecdh_nistp256, 1, NULL},
 #endif
 #endif
+#if DROPBEAR_DH_GROUP14
+#if DROPBEAR_DH_GROUP14_256
 	{"diffie-hellman-group14-sha256", 0, &kex_dh_group14_sha256, 1, NULL},
+#endif
 	{"diffie-hellman-group14-sha1", 0, &kex_dh_group14_sha1, 1, NULL},
+#endif
+#if DROPBEAR_DH_GROUP1
 	{"diffie-hellman-group1-sha1", 0, &kex_dh_group1, 1, NULL},
-#ifdef DROPBEAR_DH_GROUP15
-	{"diffie-hellman-group15-sha256", 0, &kex_dh_group15_sha256, 1, NULL},
 #endif
-#ifdef DROPBEAR_DH_GROUP16
-	{"diffie-hellman-group16-sha256", 0, &kex_dh_group16_sha256, 1, NULL},
+#if DROPBEAR_DH_GROUP16
+	{"diffie-hellman-group16-sha512", 0, &kex_dh_group16_sha512, 1, NULL},
 #endif
 #ifdef USE_KEXGUESS2
 	{KEXGUESS2_ALGO_NAME, KEXGUESS2_ALGO_ID, NULL, 1, NULL},
diff --git a/dh_groups.c b/dh_groups.c
index 205dea3..44ee830 100644
--- a/dh_groups.c
+++ b/dh_groups.c
@@ -1,6 +1,7 @@
 #include "options.h"
 #include "dh_groups.h"
 
+#if DROPBEAR_DH_GROUP1
 /* diffie-hellman-group1-sha1 value for p */
 const unsigned char dh_p_1[DH_P_1_LEN] = {
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
@@ -14,7 +15,9 @@ const unsigned char dh_p_1[DH_P_1_LEN] = {
 	0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
 	0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
+#endif /* DROPBEAR_DH_GROUP1 */
 
+#if DROPBEAR_DH_GROUP14
 /* diffie-hellman-group14-sha1 value for p */
 const unsigned char dh_p_14[DH_P_14_LEN] = {
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2, 
@@ -39,46 +42,9 @@ const unsigned char dh_p_14[DH_P_14_LEN] = {
 	0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
 	0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAC, 0xAA, 0x68, 0xFF, 0xFF, 0xFF, 0xFF,
 	0xFF, 0xFF, 0xFF, 0xFF};
+#endif /* DROPBEAR_DH_GROUP14 */
 
-#ifdef DROPBEAR_DH_GROUP15
-/* diffie-hellman-group15-sha256 value for p */
-const unsigned char dh_p_15[DH_P_15_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,
-	0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
-	0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
-	0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
-	0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
-	0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
-	0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
-	0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
-	0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
-	0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
-	0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
-	0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
-	0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
-	0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
-	0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
-	0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
-	0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
-	0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
-	0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAA, 0xC4, 0x2D, 0xAD, 0x33, 0x17, 0x0D,
-	0x04, 0x50, 0x7A, 0x33, 0xA8, 0x55, 0x21, 0xAB, 0xDF, 0x1C, 0xBA, 0x64,
-	0xEC, 0xFB, 0x85, 0x04, 0x58, 0xDB, 0xEF, 0x0A, 0x8A, 0xEA, 0x71, 0x57,
-	0x5D, 0x06, 0x0C, 0x7D, 0xB3, 0x97, 0x0F, 0x85, 0xA6, 0xE1, 0xE4, 0xC7,
-	0xAB, 0xF5, 0xAE, 0x8C, 0xDB, 0x09, 0x33, 0xD7, 0x1E, 0x8C, 0x94, 0xE0,
-	0x4A, 0x25, 0x61, 0x9D, 0xCE, 0xE3, 0xD2, 0x26, 0x1A, 0xD2, 0xEE, 0x6B,
-	0xF1, 0x2F, 0xFA, 0x06, 0xD9, 0x8A, 0x08, 0x64, 0xD8, 0x76, 0x02, 0x73,
-	0x3E, 0xC8, 0x6A, 0x64, 0x52, 0x1F, 0x2B, 0x18, 0x17, 0x7B, 0x20, 0x0C,
-	0xBB, 0xE1, 0x17, 0x57, 0x7A, 0x61, 0x5D, 0x6C, 0x77, 0x09, 0x88, 0xC0,
-	0xBA, 0xD9, 0x46, 0xE2, 0x08, 0xE2, 0x4F, 0xA0, 0x74, 0xE5, 0xAB, 0x31,
-	0x43, 0xDB, 0x5B, 0xFC, 0xE0, 0xFD, 0x10, 0x8E, 0x4B, 0x82, 0xD1, 0x20,
-	0xA9, 0x3A, 0xD2, 0xCA, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
-#endif /* DROPBEAR_DH_GROUP15 */
-
-
-#ifdef DROPBEAR_DH_GROUP16
+#if DROPBEAR_DH_GROUP16
 /* diffie-hellman-group16-256 value for p */
 const unsigned char dh_p_16[DH_P_16_LEN] = {
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2, 0x21,
@@ -123,6 +89,6 @@ const unsigned char dh_p_16[DH_P_16_LEN] = {
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
 #endif /* DROPBEAR_DH_GROUP16 */
 
-/* Same for group1 and group14 */
+/* Same for all groups */
 const int DH_G_VAL = 2;
 
diff --git a/dh_groups.h b/dh_groups.h
index 7fadac2..cddaa17 100644
--- a/dh_groups.h
+++ b/dh_groups.h
@@ -2,17 +2,17 @@
 #define DROPBEAR_DH_GROUPS_H
 #include "options.h"
 
+#if DROPBEAR_DH_GROUP1
 #define DH_P_1_LEN 128
 extern const unsigned char dh_p_1[DH_P_1_LEN];
+#endif
+
+#if DROPBEAR_DH_GROUP14
 #define DH_P_14_LEN 256
 extern const unsigned char dh_p_14[DH_P_14_LEN];
-
-#ifdef DROPBEAR_DH_GROUP15
-#define DH_P_15_LEN 384
-extern const unsigned char dh_p_15[DH_P_15_LEN];
 #endif
 
-#ifdef DROPBEAR_DH_GROUP16
+#if DROPBEAR_DH_GROUP16
 #define DH_P_16_LEN 512
 extern const unsigned char dh_p_16[DH_P_16_LEN];
 #endif
diff --git a/options.h b/options.h
index 1be412b..0c51bb1 100644
--- a/options.h
+++ b/options.h
@@ -152,11 +152,6 @@ If you test it please contact the Dropbear author */
  * on x86-64 */
 #define DROPBEAR_ECDSA
 
-/* These larger DH groups (3072 and 4096 bit respectively) add to binary size 
-    and may be significantly slower. Usually ECDH or curve25519 will be a better option */
-/*#define DROPBEAR_DH_GROUP15*/
-/*#define DROPBEAR_DH_GROUP16*/
-
 /* Generate hostkeys as-needed when the first connection using that key type occurs.
    This avoids the need to otherwise run "dropbearkey" and avoids some problems
    with badly seeded /dev/urandom when systems first boot.
@@ -173,6 +168,11 @@ If you test it please contact the Dropbear author */
  * ECDSA above */
 #define DROPBEAR_ECDH
 
+/* Group14 (2048 bit) is recommended. Group1 is less secure (1024 bit) though
+   is the only option for interoperability with some older SSH programs */
+#define DROPBEAR_DH_GROUP1 1
+#define DROPBEAR_DH_GROUP14 1
+
 /* Control the memory/performance/compression tradeoff for zlib.
  * Set windowBits=8 for least memory usage, see your system's
  * zlib.h for full details.
diff --git a/sysoptions.h b/sysoptions.h
index 85ef718..8ce4361 100644
--- a/sysoptions.h
+++ b/sysoptions.h
@@ -113,20 +113,25 @@
 #define RSA_BLINDING
 
 /* hashes which will be linked and registered */
-#if defined(DROPBEAR_SHA2_256_HMAC) || defined(DROPBEAR_ECC_256) || defined(DROPBEAR_CURVE25519)
+#if defined(DROPBEAR_SHA2_256_HMAC) || defined(DROPBEAR_ECC_256) || defined(DROPBEAR_CURVE25519) || DROPBEAR_DH_GROUP14
 #define DROPBEAR_SHA256
 #endif
 #if defined(DROPBEAR_ECC_384)
 #define DROPBEAR_SHA384
 #endif
 /* LTC SHA384 depends on SHA512 */
-#if defined(DROPBEAR_SHA2_512_HMAC) || defined(DROPBEAR_ECC_521) || defined(DROPBEAR_ECC_384)
+#if defined(DROPBEAR_SHA2_512_HMAC) || defined(DROPBEAR_ECC_521) || defined(DROPBEAR_ECC_384) || DROPBEAR_DH_GROUP16
 #define DROPBEAR_SHA512
 #endif
 #if defined(DROPBEAR_MD5_HMAC)
 #define DROPBEAR_MD5
 #endif
 
+/* These are disabled in Dropbear 2016.73 by default since the spec 
+   draft-ietf-curdle-ssh-kex-sha2-02 is under development. */
+#define DROPBEAR_DH_GROUP14_256 0
+#define DROPBEAR_DH_GROUP16 0
+
 /* roughly 2x 521 bits */
 #define MAX_ECC_SIZE 140