Add Chacha20-Poly1305, AES128-GCM and AES256-GCM support (#93) * Add Chacha20-Poly1305 authenticated encryption * Add general AEAD approach. * Add [email protected] algo using LibTomCrypt chacha and poly1305 routines. Chacha20-Poly1305 is generally faster than AES256 on CPU w/o dedicated AES instructions, having the same key size. Compiling in will add ~5,5kB to binary size on x86-64. function old new delta chacha_crypt - 1397 +1397 _poly1305_block - 608 +608 poly1305_done - 595 +595 dropbear_chachapoly_crypt - 457 +457 .rodata 26976 27392 +416 poly1305_process - 290 +290 poly1305_init - 221 +221 chacha_setup - 218 +218 encrypt_packet 1068 1270 +202 dropbear_chachapoly_getlength - 147 +147 decrypt_packet 756 897 +141 chacha_ivctr64 - 137 +137 read_packet 543 637 +94 dropbear_chachapoly_start - 94 +94 read_kex_algos 792 880 +88 chacha_keystream - 69 +69 dropbear_mode_chachapoly - 48 +48 sshciphers 280 320 +40 dropbear_mode_none 24 48 +24 dropbear_mode_ctr 24 48 +24 dropbear_mode_cbc 24 48 +24 dropbear_chachapoly_mac - 24 +24 dropbear_chachapoly - 24 +24 gen_new_keys 848 854 +6 ------------------------------------------------------------------------------ (add/remove: 14/0 grow/shrink: 10/0 up/down: 5388/0) Total: 5388 bytes * Add AES128-GCM and AES256-GCM authenticated encryption * Add general AES-GCM mode. * Add [email protected] and [email protected] algo using LibTomCrypt gcm routines. AES-GCM is combination of AES CTR mode and GHASH, slower than AES-CTR on CPU w/o dedicated AES/GHASH instructions therefore disabled by default. Compiling in will add ~6kB to binary size on x86-64. function old new delta gcm_process - 1060 +1060 .rodata 26976 27808 +832 gcm_gf_mult - 820 +820 gcm_add_aad - 660 +660 gcm_shift_table - 512 +512 gcm_done - 471 +471 gcm_add_iv - 384 +384 gcm_init - 347 +347 dropbear_gcm_crypt - 309 +309 encrypt_packet 1068 1270 +202 decrypt_packet 756 897 +141 gcm_reset - 118 +118 read_packet 543 637 +94 read_kex_algos 792 880 +88 sshciphers 280 360 +80 gcm_mult_h - 80 +80 dropbear_gcm_start - 62 +62 dropbear_mode_gcm - 48 +48 dropbear_mode_none 24 48 +24 dropbear_mode_ctr 24 48 +24 dropbear_mode_cbc 24 48 +24 dropbear_ghash - 24 +24 dropbear_gcm_getlength - 24 +24 gen_new_keys 848 854 +6 ------------------------------------------------------------------------------ (add/remove: 14/0 grow/shrink: 10/0 up/down: 6434/0) Total: 6434 bytes

--- a/common-algo.c	Mon May 25 18:28:27 2020 +0500
+++ b/common-algo.c	Mon May 25 20:50:25 2020 +0500
@@ -30,6 +30,8 @@
 #include "dh_groups.h"
 #include "ltc_prng.h"
 #include "ecc.h"
+#include "gcm.h"
+#include "chachapoly.h"
 
 /* This file (algo.c) organises the ciphers which can be used, and is used to
  * decide which ciphers/hashes/compression/signing to use during key exchange*/
@@ -86,11 +88,11 @@
  * about the symmetric_CBC vs symmetric_CTR cipher_state pointer */
 #if DROPBEAR_ENABLE_CBC_MODE
 const struct dropbear_cipher_mode dropbear_mode_cbc =
-	{(void*)cbc_start, (void*)cbc_encrypt, (void*)cbc_decrypt};
+	{(void*)cbc_start, (void*)cbc_encrypt, (void*)cbc_decrypt, NULL, NULL, NULL};
 #endif /* DROPBEAR_ENABLE_CBC_MODE */
 
 const struct dropbear_cipher_mode dropbear_mode_none =
-	{void_start, void_cipher, void_cipher};
+	{void_start, void_cipher, void_cipher, NULL, NULL, NULL};
 
 #if DROPBEAR_ENABLE_CTR_MODE
 /* a wrapper to make ctr_start and cbc_start look the same */
@@ -101,7 +103,7 @@
 	return ctr_start(cipher, IV, key, keylen, num_rounds, CTR_COUNTER_BIG_ENDIAN, ctr);
 }
 const struct dropbear_cipher_mode dropbear_mode_ctr =
-	{(void*)dropbear_big_endian_ctr_start, (void*)ctr_encrypt, (void*)ctr_decrypt};
+	{(void*)dropbear_big_endian_ctr_start, (void*)ctr_encrypt, (void*)ctr_decrypt, NULL, NULL, NULL};
 #endif /* DROPBEAR_ENABLE_CTR_MODE */
 
 /* Mapping of ssh hashes to libtomcrypt hashes, including keysize etc.
@@ -137,6 +139,19 @@
  * that is also supported by the server will get used. */
 
 algo_type sshciphers[] = {
+#if DROPBEAR_CHACHA20POLY1305
+	{"[email protected]", 0, &dropbear_chachapoly, 1, &dropbear_mode_chachapoly},
+#endif
+
+#if DROPBEAR_ENABLE_GCM_MODE
+#if DROPBEAR_AES128
+	{"[email protected]", 0, &dropbear_aes128, 1, &dropbear_mode_gcm},
+#endif
+#if DROPBEAR_AES256
+	{"[email protected]", 0, &dropbear_aes256, 1, &dropbear_mode_gcm},
+#endif
+#endif /* DROPBEAR_ENABLE_GCM_MODE */
+
 #if DROPBEAR_ENABLE_CTR_MODE
 #if DROPBEAR_AES128
 	{"aes128-ctr", 0, &dropbear_aes128, 1, &dropbear_mode_ctr},