version 1.21, 2000/09/27 21:41:34 |
version 1.22, 2000/10/11 04:02:17 |
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#include "dispatch.h" |
#include "dispatch.h" |
#include "authfd.h" |
#include "authfd.h" |
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void ssh_dh1_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); |
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void ssh_dhgex_client(Kex *, char *, struct sockaddr *, Buffer *, Buffer *); |
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/* import */ |
/* import */ |
extern char *client_version_string; |
extern char *client_version_string; |
extern char *server_version_string; |
extern char *server_version_string; |
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int session_id2_len = 0; |
int session_id2_len = 0; |
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void |
void |
ssh_kex_dh(Kex *kex, char *host, struct sockaddr *hostaddr, |
ssh_kex2(char *host, struct sockaddr *hostaddr) |
Buffer *client_kexinit, Buffer *server_kexinit) |
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{ |
{ |
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int i, plen; |
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Kex *kex; |
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Buffer *client_kexinit, *server_kexinit; |
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char *sprop[PROPOSAL_MAX]; |
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if (options.ciphers != NULL) { |
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myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
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myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
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} else if (options.cipher == SSH_CIPHER_3DES) { |
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myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
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myproposal[PROPOSAL_ENC_ALGS_STOC] = |
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(char *) cipher_name(SSH_CIPHER_3DES_CBC); |
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} else if (options.cipher == SSH_CIPHER_BLOWFISH) { |
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myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
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myproposal[PROPOSAL_ENC_ALGS_STOC] = |
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(char *) cipher_name(SSH_CIPHER_BLOWFISH_CBC); |
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} |
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if (options.compression) { |
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myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib"; |
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myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; |
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} else { |
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myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none"; |
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myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; |
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} |
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/* buffers with raw kexinit messages */ |
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server_kexinit = xmalloc(sizeof(*server_kexinit)); |
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buffer_init(server_kexinit); |
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client_kexinit = kex_init(myproposal); |
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/* algorithm negotiation */ |
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kex_exchange_kexinit(client_kexinit, server_kexinit, sprop); |
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kex = kex_choose_conf(myproposal, sprop, 0); |
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for (i = 0; i < PROPOSAL_MAX; i++) |
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xfree(sprop[i]); |
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/* server authentication and session key agreement */ |
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switch(kex->kex_type) { |
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case DH_GRP1_SHA1: |
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ssh_dh1_client(kex, host, hostaddr, |
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client_kexinit, server_kexinit); |
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break; |
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case DH_GEX_SHA1: |
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ssh_dhgex_client(kex, host, hostaddr, client_kexinit, |
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server_kexinit); |
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break; |
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default: |
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fatal("Unsupported key exchange %d", kex->kex_type); |
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} |
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buffer_free(client_kexinit); |
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buffer_free(server_kexinit); |
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xfree(client_kexinit); |
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xfree(server_kexinit); |
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debug("Wait SSH2_MSG_NEWKEYS."); |
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packet_read_expect(&plen, SSH2_MSG_NEWKEYS); |
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packet_done(); |
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debug("GOT SSH2_MSG_NEWKEYS."); |
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debug("send SSH2_MSG_NEWKEYS."); |
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packet_start(SSH2_MSG_NEWKEYS); |
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packet_send(); |
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packet_write_wait(); |
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debug("done: send SSH2_MSG_NEWKEYS."); |
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#ifdef DEBUG_KEXDH |
#ifdef DEBUG_KEXDH |
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/* send 1st encrypted/maced/compressed message */ |
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packet_start(SSH2_MSG_IGNORE); |
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packet_put_cstring("markus"); |
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packet_send(); |
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packet_write_wait(); |
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#endif |
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debug("done: KEX2."); |
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} |
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/* diffie-hellman-group1-sha1 */ |
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void |
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ssh_dh1_client(Kex *kex, char *host, struct sockaddr *hostaddr, |
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Buffer *client_kexinit, Buffer *server_kexinit) |
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{ |
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#ifdef DEBUG_KEXDH |
int i; |
int i; |
#endif |
#endif |
int plen, dlen; |
int plen, dlen; |
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fatal("cannot decode server_host_key_blob"); |
fatal("cannot decode server_host_key_blob"); |
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check_host_key(host, hostaddr, server_host_key, |
check_host_key(host, hostaddr, server_host_key, |
options.user_hostfile2, options.system_hostfile2); |
options.user_hostfile2, options.system_hostfile2); |
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/* DH paramter f, server public DH key */ |
/* DH paramter f, server public DH key */ |
dh_server_pub = BN_new(); |
dh_server_pub = BN_new(); |
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memcpy(session_id2, hash, session_id2_len); |
memcpy(session_id2, hash, session_id2_len); |
} |
} |
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/* diffie-hellman-group-exchange-sha1 */ |
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/* |
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* Estimates the group order for a Diffie-Hellman group that has an |
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* attack complexity approximately the same as O(2**bits). Estimate |
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* with: O(exp(1.9223 * (ln q)^(1/3) (ln ln q)^(2/3))) |
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*/ |
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int |
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dh_estimate(int bits) |
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{ |
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if (bits < 64) |
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return (512); /* O(2**63) */ |
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if (bits < 128) |
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return (1024); /* O(2**86) */ |
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if (bits < 192) |
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return (2048); /* O(2**116) */ |
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return (4096); /* O(2**156) */ |
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} |
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void |
void |
ssh_kex2(char *host, struct sockaddr *hostaddr) |
ssh_dhgex_client(Kex *kex, char *host, struct sockaddr *hostaddr, |
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Buffer *client_kexinit, Buffer *server_kexinit) |
{ |
{ |
int i, plen; |
#ifdef DEBUG_KEXDH |
Kex *kex; |
int i; |
Buffer *client_kexinit, *server_kexinit; |
#endif |
char *sprop[PROPOSAL_MAX]; |
int plen, dlen; |
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unsigned int klen, kout; |
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char *signature = NULL; |
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unsigned int slen, nbits; |
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char *server_host_key_blob = NULL; |
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Key *server_host_key; |
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unsigned int sbloblen; |
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DH *dh; |
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BIGNUM *dh_server_pub = 0; |
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BIGNUM *shared_secret = 0; |
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BIGNUM *p = 0, *g = 0; |
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unsigned char *kbuf; |
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unsigned char *hash; |
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if (options.ciphers != NULL) { |
nbits = dh_estimate(kex->enc[MODE_OUT].key_len * 8); |
myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
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myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
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} else if (options.cipher == SSH_CIPHER_3DES) { |
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myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
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myproposal[PROPOSAL_ENC_ALGS_STOC] = |
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(char *) cipher_name(SSH_CIPHER_3DES_CBC); |
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} else if (options.cipher == SSH_CIPHER_BLOWFISH) { |
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myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
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myproposal[PROPOSAL_ENC_ALGS_STOC] = |
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(char *) cipher_name(SSH_CIPHER_BLOWFISH_CBC); |
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} |
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if (options.compression) { |
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myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib"; |
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myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; |
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} else { |
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myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none"; |
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myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; |
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} |
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/* buffers with raw kexinit messages */ |
debug("Sending SSH2_MSG_KEX_DH_GEX_REQUEST."); |
server_kexinit = xmalloc(sizeof(*server_kexinit)); |
packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST); |
buffer_init(server_kexinit); |
packet_put_int(nbits); |
client_kexinit = kex_init(myproposal); |
packet_send(); |
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packet_write_wait(); |
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/* algorithm negotiation */ |
#ifdef DEBUG_KEXDH |
kex_exchange_kexinit(client_kexinit, server_kexinit, sprop); |
fprintf(stderr, "\nnbits = %d", nbits); |
kex = kex_choose_conf(myproposal, sprop, 0); |
#endif |
for (i = 0; i < PROPOSAL_MAX; i++) |
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xfree(sprop[i]); |
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/* server authentication and session key agreement */ |
debug("Wait SSH2_MSG_KEX_DH_GEX_GROUP."); |
ssh_kex_dh(kex, host, hostaddr, client_kexinit, server_kexinit); |
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buffer_free(client_kexinit); |
packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_GROUP); |
buffer_free(server_kexinit); |
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xfree(client_kexinit); |
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xfree(server_kexinit); |
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debug("Wait SSH2_MSG_NEWKEYS."); |
debug("Got SSH2_MSG_KEX_DH_GEX_GROUP."); |
packet_read_expect(&plen, SSH2_MSG_NEWKEYS); |
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packet_done(); |
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debug("GOT SSH2_MSG_NEWKEYS."); |
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debug("send SSH2_MSG_NEWKEYS."); |
if ((p = BN_new()) == NULL) |
packet_start(SSH2_MSG_NEWKEYS); |
fatal("BN_new"); |
packet_send(); |
packet_get_bignum2(p, &dlen); |
packet_write_wait(); |
if ((g = BN_new()) == NULL) |
debug("done: send SSH2_MSG_NEWKEYS."); |
fatal("BN_new"); |
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packet_get_bignum2(g, &dlen); |
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if ((dh = dh_new_group(g, p)) == NULL) |
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fatal("dh_new_group"); |
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#ifdef DEBUG_KEXDH |
#ifdef DEBUG_KEXDH |
/* send 1st encrypted/maced/compressed message */ |
fprintf(stderr, "\np= "); |
packet_start(SSH2_MSG_IGNORE); |
BN_print_fp(stderr, dh->p); |
packet_put_cstring("markus"); |
fprintf(stderr, "\ng= "); |
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BN_print_fp(stderr, dh->g); |
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fprintf(stderr, "\npub= "); |
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BN_print_fp(stderr, dh->pub_key); |
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fprintf(stderr, "\n"); |
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DHparams_print_fp(stderr, dh); |
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#endif |
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debug("Sending SSH2_MSG_KEX_DH_GEX_INIT."); |
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/* generate and send 'e', client DH public key */ |
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packet_start(SSH2_MSG_KEX_DH_GEX_INIT); |
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packet_put_bignum2(dh->pub_key); |
packet_send(); |
packet_send(); |
packet_write_wait(); |
packet_write_wait(); |
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debug("Wait SSH2_MSG_KEX_DH_GEX_REPLY."); |
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packet_read_expect(&plen, SSH2_MSG_KEX_DH_GEX_REPLY); |
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debug("Got SSH2_MSG_KEXDH_REPLY."); |
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/* key, cert */ |
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server_host_key_blob = packet_get_string(&sbloblen); |
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server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen); |
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if (server_host_key == NULL) |
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fatal("cannot decode server_host_key_blob"); |
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check_host_key(host, hostaddr, server_host_key, |
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options.user_hostfile2, options.system_hostfile2); |
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/* DH paramter f, server public DH key */ |
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dh_server_pub = BN_new(); |
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if (dh_server_pub == NULL) |
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fatal("dh_server_pub == NULL"); |
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packet_get_bignum2(dh_server_pub, &dlen); |
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#ifdef DEBUG_KEXDH |
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fprintf(stderr, "\ndh_server_pub= "); |
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BN_print_fp(stderr, dh_server_pub); |
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fprintf(stderr, "\n"); |
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debug("bits %d", BN_num_bits(dh_server_pub)); |
#endif |
#endif |
debug("done: KEX2."); |
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/* signed H */ |
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signature = packet_get_string(&slen); |
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packet_done(); |
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if (!dh_pub_is_valid(dh, dh_server_pub)) |
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packet_disconnect("bad server public DH value"); |
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klen = DH_size(dh); |
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kbuf = xmalloc(klen); |
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kout = DH_compute_key(kbuf, dh_server_pub, dh); |
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#ifdef DEBUG_KEXDH |
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debug("shared secret: len %d/%d", klen, kout); |
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fprintf(stderr, "shared secret == "); |
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for (i = 0; i< kout; i++) |
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fprintf(stderr, "%02x", (kbuf[i])&0xff); |
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fprintf(stderr, "\n"); |
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#endif |
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shared_secret = BN_new(); |
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BN_bin2bn(kbuf, kout, shared_secret); |
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memset(kbuf, 0, klen); |
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xfree(kbuf); |
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/* calc and verify H */ |
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hash = kex_hash_gex( |
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client_version_string, |
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server_version_string, |
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buffer_ptr(client_kexinit), buffer_len(client_kexinit), |
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buffer_ptr(server_kexinit), buffer_len(server_kexinit), |
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server_host_key_blob, sbloblen, |
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nbits, dh->p, dh->g, |
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dh->pub_key, |
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dh_server_pub, |
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shared_secret |
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); |
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xfree(server_host_key_blob); |
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DH_free(dh); |
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#ifdef DEBUG_KEXDH |
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fprintf(stderr, "hash == "); |
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for (i = 0; i< 20; i++) |
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fprintf(stderr, "%02x", (hash[i])&0xff); |
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fprintf(stderr, "\n"); |
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#endif |
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if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1) |
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fatal("dsa_verify failed for server_host_key"); |
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key_free(server_host_key); |
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kex_derive_keys(kex, hash, shared_secret); |
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packet_set_kex(kex); |
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/* save session id */ |
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session_id2_len = 20; |
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session_id2 = xmalloc(session_id2_len); |
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memcpy(session_id2, hash, session_id2_len); |
} |
} |
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/* |
/* |