forked from KolibriOS/kolibrios
368 lines
12 KiB
PHP
368 lines
12 KiB
PHP
; dh_gex.inc - Diffie Hellman Group exchange
|
|
;
|
|
; Copyright (C) 2015-2016 Jeffrey Amelynck
|
|
;
|
|
; This program is free software: you can redistribute it and/or modify
|
|
; it under the terms of the GNU General Public License as published by
|
|
; the Free Software Foundation, either version 3 of the License, or
|
|
; (at your option) any later version.
|
|
;
|
|
; This program is distributed in the hope that it will be useful,
|
|
; but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
; GNU General Public License for more details.
|
|
;
|
|
; You should have received a copy of the GNU General Public License
|
|
; along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
; https://www.ietf.org/rfc/rfc4419.txt
|
|
|
|
; TODO: dont convert mpints to little endian immediately.
|
|
; Or maybe even better, not at all.
|
|
|
|
proc dh_gex
|
|
|
|
;----------------------------------------------
|
|
; >> Send Diffie-Hellman Group Exchange Request
|
|
|
|
DEBUGF 2, "Sending GEX\n"
|
|
stdcall ssh_send_packet, con, ssh_gex_req, ssh_gex_req.length, 0
|
|
cmp eax, -1
|
|
je .socket_err
|
|
|
|
;---------------------------------------------
|
|
; << Parse Diffie-Hellman Group Exchange Group
|
|
|
|
stdcall ssh_recv_packet, con, 0
|
|
cmp eax, -1
|
|
je .socket_err
|
|
|
|
cmp [con.rx_buffer.message_code], SSH_MSG_KEX_DH_GEX_GROUP
|
|
jne proto_err
|
|
DEBUGF 2, "Received GEX group\n"
|
|
|
|
mov esi, con.rx_buffer+sizeof.ssh_packet_header
|
|
mov edi, con.dh_p
|
|
DEBUGF 1, "DH modulus (p): "
|
|
call mpint_to_little_endian
|
|
stdcall mpint_print, con.dh_p
|
|
|
|
DEBUGF 1, "DH base (g): "
|
|
mov edi, con.dh_g
|
|
call mpint_to_little_endian
|
|
stdcall mpint_print, con.dh_g
|
|
|
|
;-------------------------------------------
|
|
; >> Send Diffie-Hellman Group Exchange Init
|
|
|
|
; generate a random number x, where 1 < x < (p-1)/2
|
|
mov edi, con.dh_x+4
|
|
mov [con.dh_x], DH_PRIVATE_KEY_SIZE/8
|
|
mov ecx, DH_PRIVATE_KEY_SIZE/8/4
|
|
@@:
|
|
push ecx
|
|
call MBRandom
|
|
pop ecx
|
|
stosd
|
|
dec ecx
|
|
jnz @r
|
|
|
|
; If the highest bit is set, add a zero byte
|
|
shl eax, 1
|
|
jnc @f
|
|
mov byte[edi], 0
|
|
inc dword[con.dh_x]
|
|
@@:
|
|
|
|
; Fill remaining bytes with zeros ; TO BE REMOVED ?
|
|
if ((MAX_BITS-DH_PRIVATE_KEY_SIZE) > 0)
|
|
mov ecx, (MAX_BITS-DH_PRIVATE_KEY_SIZE)/8/4
|
|
xor eax, eax
|
|
rep stosd
|
|
end if
|
|
|
|
DEBUGF 1, "DH x: "
|
|
stdcall mpint_print, con.dh_x
|
|
|
|
; Compute e = g^x mod p
|
|
stdcall mpint_modexp, con.dh_e, con.dh_g, con.dh_x, con.dh_p
|
|
|
|
DEBUGF 1, "DH e: "
|
|
stdcall mpint_print, con.dh_e
|
|
|
|
; Create group exchange init packet
|
|
mov edi, con.tx_buffer.message_code
|
|
mov al, SSH_MSG_KEX_DH_GEX_INIT
|
|
stosb
|
|
mov esi, con.dh_e
|
|
call mpint_to_big_endian
|
|
|
|
DEBUGF 2, "Sending GEX init\n"
|
|
mov ecx, dword[con.tx_buffer.message_code+1]
|
|
bswap ecx
|
|
add ecx, 5
|
|
stdcall ssh_send_packet, con, con.tx_buffer.message_code, ecx, 0
|
|
cmp eax, -1
|
|
je .socket_err
|
|
|
|
;---------------------------------------------
|
|
; << Parse Diffie-Hellman Group Exchange Reply
|
|
|
|
stdcall ssh_recv_packet, con, 0
|
|
cmp eax, -1
|
|
je .socket_err
|
|
|
|
cmp [con.rx_buffer.message_code], SSH_MSG_KEX_DH_GEX_REPLY
|
|
jne .proto_err
|
|
|
|
DEBUGF 2, "Received GEX Reply\n"
|
|
|
|
;--------------------------------
|
|
; HASH: string K_S, the host key
|
|
mov esi, con.rx_buffer+sizeof.ssh_packet_header
|
|
mov edx, [esi]
|
|
bswap edx
|
|
add edx, 4
|
|
lea ebx, [esi+edx]
|
|
push ebx
|
|
invoke sha256_update, con.temp_ctx, esi, edx
|
|
|
|
;--------------------------------------------------------------------------
|
|
; HASH: uint32 min, minimal size in bits of an acceptable group
|
|
; uint32 n, preferred size in bits of the group the server will send
|
|
; uint32 max, maximal size in bits of an acceptable group
|
|
invoke sha256_update, con.temp_ctx, ssh_gex_req+sizeof.ssh_packet_header-ssh_packet_header.message_code, 12
|
|
|
|
;----------------------------
|
|
; HASH: mpint p, safe prime
|
|
mov esi, con.dh_p
|
|
mov edi, con.mpint_tmp
|
|
call mpint_to_big_endian
|
|
lea edx, [eax+4]
|
|
invoke sha256_update, con.temp_ctx, con.mpint_tmp, edx
|
|
|
|
;----------------------------------------
|
|
; HASH: mpint g, generator for subgroup
|
|
mov esi, con.dh_g
|
|
mov edi, con.mpint_tmp
|
|
call mpint_to_big_endian
|
|
lea edx, [eax+4]
|
|
invoke sha256_update, con.temp_ctx, con.mpint_tmp, edx
|
|
|
|
;---------------------------------------------------
|
|
; HASH: mpint e, exchange value sent by the client
|
|
mov esi, con.tx_buffer+sizeof.ssh_packet_header
|
|
mov edx, [esi]
|
|
bswap edx
|
|
add edx, 4
|
|
invoke sha256_update, con.temp_ctx, esi, edx
|
|
|
|
;---------------------------------------------------
|
|
; HASH: mpint f, exchange value sent by the server
|
|
mov esi, [esp]
|
|
mov edx, [esi]
|
|
bswap edx
|
|
add edx, 4
|
|
invoke sha256_update, con.temp_ctx, esi, edx
|
|
pop esi
|
|
|
|
mov edi, con.dh_f
|
|
call mpint_to_little_endian
|
|
|
|
DEBUGF 1, "DH f: "
|
|
stdcall mpint_print, con.dh_f
|
|
|
|
mov edi, con.dh_signature
|
|
call mpint_to_little_endian
|
|
|
|
DEBUGF 1, "DH signature: "
|
|
stdcall mpint_print, con.dh_signature
|
|
|
|
;--------------------------------------
|
|
; Calculate shared secret K = f^x mod p
|
|
stdcall mpint_modexp, con.rx_buffer, con.dh_f, con.dh_x, con.dh_p
|
|
|
|
DEBUGF 1, "DH K: "
|
|
stdcall mpint_print, con.rx_buffer
|
|
|
|
; We always need it in big endian order, so store it as such.
|
|
mov edi, con.dh_K
|
|
mov esi, con.rx_buffer
|
|
call mpint_to_big_endian
|
|
mov [con.dh_K_length], eax
|
|
|
|
;-----------------------------------
|
|
; HASH: mpint K, the shared secret
|
|
mov edx, [con.dh_K_length]
|
|
add edx, 4
|
|
invoke sha256_update, con.temp_ctx, con.dh_K, edx
|
|
|
|
;-------------------------------
|
|
; Finalize the exchange hash (H)
|
|
invoke sha256_final, con.temp_ctx
|
|
mov esi, con.temp_ctx.hash
|
|
mov edi, con.dh_H
|
|
mov ecx, SHA256_HASH_SIZE/4
|
|
rep movsd
|
|
|
|
DEBUGF 1, "Exchange hash H: "
|
|
stdcall dump_hex, con.dh_H, 8
|
|
|
|
; TODO: skip this block when re-keying
|
|
mov esi, con.dh_H
|
|
mov edi, con.session_id
|
|
mov ecx, SHA256_HASH_SIZE/4
|
|
rep movsd
|
|
|
|
;---------------
|
|
; Calculate keys
|
|
|
|
; First, calculate partial hash of K and H so we can re-use it for every key.
|
|
|
|
invoke sha256_init, con.k_h_ctx
|
|
|
|
mov edx, [con.dh_K_length]
|
|
add edx, 4
|
|
invoke sha256_update, con.k_h_ctx, con.dh_K, edx
|
|
invoke sha256_update, con.k_h_ctx, con.dh_H, 32
|
|
|
|
;---------------------------------------------------------------
|
|
; Initial IV client to server: HASH(K || H || "A" || session_id)
|
|
|
|
mov esi, con.k_h_ctx
|
|
mov edi, con.temp_ctx
|
|
mov ecx, sizeof.ctx_sha224256/4
|
|
rep movsd
|
|
mov [con.session_id_prefix], 'A'
|
|
invoke sha256_update, con.temp_ctx, con.session_id_prefix, 32+1
|
|
invoke sha256_final, con.temp_ctx.hash
|
|
mov edi, con.tx_iv
|
|
mov esi, con.temp_ctx
|
|
mov ecx, SHA256_HASH_SIZE/4
|
|
rep movsd
|
|
|
|
DEBUGF 1, "Remote IV: "
|
|
stdcall dump_hex, con.tx_iv, 8
|
|
|
|
;---------------------------------------------------------------
|
|
; Initial IV server to client: HASH(K || H || "B" || session_id)
|
|
|
|
mov esi, con.k_h_ctx
|
|
mov edi, con.temp_ctx
|
|
mov ecx, sizeof.ctx_sha224256/4
|
|
rep movsd
|
|
inc [con.session_id_prefix]
|
|
invoke sha256_update, con.temp_ctx, con.session_id_prefix, 32+1
|
|
invoke sha256_final, con.temp_ctx
|
|
mov edi, con.rx_iv
|
|
mov esi, con.temp_ctx
|
|
mov ecx, SHA256_HASH_SIZE/4
|
|
rep movsd
|
|
|
|
DEBUGF 1, "Local IV: "
|
|
stdcall dump_hex, con.rx_iv, 8
|
|
|
|
;-------------------------------------------------------------------
|
|
; Encryption key client to server: HASH(K || H || "C" || session_id)
|
|
|
|
mov esi, con.k_h_ctx
|
|
mov edi, con.temp_ctx
|
|
mov ecx, sizeof.ctx_sha224256/4
|
|
rep movsd
|
|
inc [con.session_id_prefix]
|
|
invoke sha256_update, con.temp_ctx, con.session_id_prefix, 32+1
|
|
invoke sha256_final, con.temp_ctx
|
|
mov edi, con.tx_enc_key
|
|
mov esi, con.temp_ctx
|
|
mov ecx, SHA256_HASH_SIZE/4
|
|
rep movsd
|
|
|
|
DEBUGF 1, "Remote key: "
|
|
stdcall dump_hex, con.tx_enc_key, 8
|
|
|
|
;-------------------------------------------------------------------
|
|
; Encryption key server to client: HASH(K || H || "D" || session_id)
|
|
|
|
mov esi, con.k_h_ctx
|
|
mov edi, con.temp_ctx
|
|
mov ecx, sizeof.ctx_sha224256/4
|
|
rep movsd
|
|
inc [con.session_id_prefix]
|
|
invoke sha256_update, con.temp_ctx, con.session_id_prefix, 32+1
|
|
invoke sha256_final, con.temp_ctx
|
|
mov edi, con.rx_enc_key
|
|
mov esi, con.temp_ctx
|
|
mov ecx, SHA256_HASH_SIZE/4
|
|
rep movsd
|
|
|
|
DEBUGF 1, "Local key: "
|
|
stdcall dump_hex, con.rx_enc_key, 8
|
|
|
|
;------------------------------------------------------------------
|
|
; Integrity key client to server: HASH(K || H || "E" || session_id)
|
|
|
|
mov esi, con.k_h_ctx
|
|
mov edi, con.temp_ctx
|
|
mov ecx, sizeof.ctx_sha224256/4
|
|
rep movsd
|
|
inc [con.session_id_prefix]
|
|
invoke sha256_update, con.temp_ctx, con.session_id_prefix, 32+1
|
|
invoke sha256_final, con.temp_ctx
|
|
mov edi, con.tx_int_key
|
|
mov esi, con.temp_ctx
|
|
mov ecx, SHA256_HASH_SIZE/4
|
|
rep movsd
|
|
|
|
DEBUGF 1, "Remote Integrity key: "
|
|
stdcall dump_hex, con.tx_int_key, 8
|
|
|
|
;------------------------------------------------------------------
|
|
; Integrity key server to client: HASH(K || H || "F" || session_id)
|
|
|
|
mov esi, con.k_h_ctx
|
|
mov edi, con.temp_ctx
|
|
mov ecx, sizeof.ctx_sha224256/4
|
|
rep movsd
|
|
inc [con.session_id_prefix]
|
|
invoke sha256_update, con.temp_ctx, con.session_id_prefix, 32+1
|
|
invoke sha256_final, con.temp_ctx
|
|
mov edi, con.rx_int_key
|
|
mov esi, con.temp_ctx
|
|
mov ecx, SHA256_HASH_SIZE/4
|
|
rep movsd
|
|
|
|
DEBUGF 1, "Local Integrity key: "
|
|
stdcall dump_hex, con.rx_int_key, 8
|
|
|
|
;-------------------------------------
|
|
; << Parse Diffie-Hellman New Keys MSG
|
|
|
|
stdcall ssh_recv_packet, con, 0
|
|
cmp eax, -1
|
|
je .socket_err
|
|
|
|
cmp [con.rx_buffer.message_code], SSH_MSG_NEWKEYS
|
|
jne .proto_err
|
|
|
|
DEBUGF 2, "Received New Keys\n"
|
|
|
|
;-------------------------------
|
|
; >> Reply with New Keys message
|
|
|
|
stdcall ssh_send_packet, con, ssh_new_keys, ssh_new_keys.length, 0
|
|
|
|
xor eax, eax
|
|
ret
|
|
|
|
.socket_err:
|
|
DEBUGF 3, "Socket error during key exchange!\n"
|
|
mov eax, 1
|
|
ret
|
|
|
|
.proto_err:
|
|
DEBUGF 3, "Protocol error during key exchange!\n"
|
|
mov eax, 2
|
|
ret
|
|
|
|
endp
|