puttygen : [G] winpgen sshrsag sshdssg sshprime sshdes sshbn sshmd5 version
+ sshrand winnoise sshsha winstore misc winctrls sshrsa sshdss winmisc
- + sshpubk sshaes sshsh512 import winutils puttygen.res tree234
- + notiming winhelp LIBS wintime
+ + sshpubk sshaes sshsh256 sshsh512 import winutils puttygen.res
+ + tree234 notiming winhelp LIBS wintime
pterm : [X] GTKTERM uxmisc misc ldisc settings uxpty uxsel BE_NONE uxstore
+ uxsignal CHARSET cmdline uxpterm version time xpmpterm xpmptcfg
puttygen : [U] cmdgen sshrsag sshdssg sshprime sshdes sshbn sshmd5 version
+ sshrand uxnoise sshsha misc sshrsa sshdss uxcons uxstore uxmisc
- + sshpubk sshaes sshsh512 import puttygen.res time tree234 uxgen
- + notiming
+ + sshpubk sshaes sshsh256 sshsh512 import puttygen.res time tree234
+ + uxgen notiming
pscp : [U] pscp uxsftp uxcons UXSSH BE_SSH SFTP wildcard UXMISC
psftp : [U] psftp uxsftp uxcons UXSSH BE_SSH SFTP wildcard UXMISC
+ CHARSET stricmp vsnprint dialog config macctrls minibidi
PuTTYgen : [M] macpgen sshrsag sshdssg sshprime sshdes sshbn sshmd5 version
+ sshrand macnoise sshsha macstore misc sshrsa sshdss macmisc sshpubk
- + sshaes sshsh512 import macpgen.rsrc macpgkey macabout
+ + sshaes sshsh256 sshsh512 import macpgen.rsrc macpgkey macabout
PuTTY : [MX] osxmain OSXTERM OSXMISC CHARSET U_BE_ALL NONSSH UXSSH
+ ux_x11 uxpty uxsignal testback putty.icns info.plist
{ "Diffie-Hellman group 1", KEX_DHGROUP1 },
{ "Diffie-Hellman group 14", KEX_DHGROUP14 },
{ "Diffie-Hellman group exchange", KEX_DHGEX },
+ { "RSA-based key exchange", KEX_RSA },
{ "-- warn below here --", KEX_WARN }
};
invent new ones over time, without any changes required to PuTTY's
configuration. We recommend use of this method, if possible.
+In addition, PuTTY supports \i{RSA key exchange}, which requires much less
+computational effort on the part of the client, and somewhat less on
+the part of the server, than Diffie-Hellman key exchange.
+
If the first algorithm PuTTY finds is below the \q{warn below here}
line, you will see a warning box when you make the connection, similar
to that for cipher selection (see \k{config-ssh-encryption}).
KEX_DHGROUP1,
KEX_DHGROUP14,
KEX_DHGEX,
+ KEX_RSA,
KEX_MAX
};
{ "dh-gex-sha1", KEX_DHGEX },
{ "dh-group14-sha1", KEX_DHGROUP14 },
{ "dh-group1-sha1", KEX_DHGROUP1 },
+ { "rsa", KEX_RSA },
{ "WARN", KEX_WARN }
};
char *default_kexes;
gppi(sesskey, "BugDHGEx2", 0, &i); i = 2-i;
if (i == FORCE_ON)
- default_kexes = "dh-group14-sha1,dh-group1-sha1,WARN,dh-gex-sha1";
+ default_kexes = "dh-group14-sha1,dh-group1-sha1,rsa,WARN,dh-gex-sha1";
else
- default_kexes = "dh-gex-sha1,dh-group14-sha1,dh-group1-sha1,WARN";
+ default_kexes = "dh-gex-sha1,dh-group14-sha1,dh-group1-sha1,rsa,WARN";
gprefs(sesskey, "KEX", default_kexes,
kexnames, KEX_MAX, cfg->ssh_kexlist);
}
#define SSH2_MSG_KEX_DH_GEX_GROUP 31 /* 0x1f */
#define SSH2_MSG_KEX_DH_GEX_INIT 32 /* 0x20 */
#define SSH2_MSG_KEX_DH_GEX_REPLY 33 /* 0x21 */
+#define SSH2_MSG_KEXRSA_PUBKEY 30 /* 0x1e */
+#define SSH2_MSG_KEXRSA_SECRET 31 /* 0x1f */
+#define SSH2_MSG_KEXRSA_DONE 32 /* 0x20 */
#define SSH2_MSG_USERAUTH_REQUEST 50 /* 0x32 */
#define SSH2_MSG_USERAUTH_FAILURE 51 /* 0x33 */
#define SSH2_MSG_USERAUTH_SUCCESS 52 /* 0x34 */
*/
#define SSH2_PKTCTX_DHGROUP 0x0001
#define SSH2_PKTCTX_DHGEX 0x0002
+#define SSH2_PKTCTX_RSAKEX 0x0004
#define SSH2_PKTCTX_KEX_MASK 0x000F
#define SSH2_PKTCTX_PUBLICKEY 0x0010
#define SSH2_PKTCTX_PASSWORD 0x0020
translatec(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
translatec(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
translatec(SSH2_MSG_KEX_DH_GEX_REPLY, SSH2_PKTCTX_DHGEX);
+ translatec(SSH2_MSG_KEXRSA_PUBKEY, SSH2_PKTCTX_RSAKEX);
+ translatec(SSH2_MSG_KEXRSA_SECRET, SSH2_PKTCTX_RSAKEX);
+ translatec(SSH2_MSG_KEXRSA_DONE, SSH2_PKTCTX_RSAKEX);
translate(SSH2_MSG_USERAUTH_REQUEST);
translate(SSH2_MSG_USERAUTH_FAILURE);
translate(SSH2_MSG_USERAUTH_SUCCESS);
const struct ssh_mac *scmac_tobe;
const struct ssh_compress *cscomp_tobe;
const struct ssh_compress *sccomp_tobe;
- char *hostkeydata, *sigdata, *keystr, *fingerprint;
- int hostkeylen, siglen;
+ char *hostkeydata, *sigdata, *rsakeydata, *keystr, *fingerprint;
+ int hostkeylen, siglen, rsakeylen;
void *hkey; /* actual host key */
+ void *rsakey; /* for RSA kex */
unsigned char exchange_hash[SSH2_KEX_MAX_HASH_LEN];
int n_preferred_kex;
const struct ssh_kexes *preferred_kex[KEX_MAX];
s->preferred_kex[s->n_preferred_kex++] =
&ssh_diffiehellman_group1;
break;
+ case KEX_RSA:
+ s->preferred_kex[s->n_preferred_kex++] =
+ &ssh_rsa_kex;
+ break;
case KEX_WARN:
/* Flag for later. Don't bother if it's the last in
* the list. */
crWaitUntil(pktin); /* Ignore packet */
}
+ if (ssh->kex->main_type == KEXTYPE_DH) {
+ /* XXX The lines below should be reindented before this is committed.*/
/*
* Work out the number of bits of key we will need from the key
* exchange. We start with the maximum key length of either
}
set_busy_status(ssh->frontend, BUSY_CPU); /* cogitate */
ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
+ s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
s->f = ssh2_pkt_getmp(pktin);
if (!s->f) {
bombout(("unable to parse key exchange reply packet"));
}
hash_mpint(ssh->kex->hash, ssh->exhash, s->e);
hash_mpint(ssh->kex->hash, ssh->exhash, s->f);
+
+ dh_cleanup(ssh->kex_ctx);
+ freebn(s->f);
+ if (!ssh->kex->pdata) {
+ freebn(s->g);
+ freebn(s->p);
+ }
+ /* XXX end incorrectly-indented section */
+ } else {
+ logeventf(ssh, "Doing RSA key exchange with hash %s",
+ ssh->kex->hash->text_name);
+ ssh->pkt_ctx |= SSH2_PKTCTX_RSAKEX;
+ /*
+ * RSA key exchange. First expect a KEXRSA_PUBKEY packet
+ * from the server.
+ */
+ crWaitUntil(pktin);
+ if (pktin->type != SSH2_MSG_KEXRSA_PUBKEY) {
+ bombout(("expected RSA public key packet from server"));
+ crStop(0);
+ }
+
+ ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
+ hash_string(ssh->kex->hash, ssh->exhash,
+ s->hostkeydata, s->hostkeylen);
+ s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
+
+ {
+ char *keydata;
+ ssh_pkt_getstring(pktin, &keydata, &s->rsakeylen);
+ s->rsakeydata = snewn(s->rsakeylen, char);
+ memcpy(s->rsakeydata, keydata, s->rsakeylen);
+ }
+
+ s->rsakey = ssh_rsakex_newkey(s->rsakeydata, s->rsakeylen);
+ if (!s->rsakey) {
+ sfree(s->rsakeydata);
+ bombout(("unable to parse RSA public key from server"));
+ crStop(0);
+ }
+
+ hash_string(ssh->kex->hash, ssh->exhash, s->rsakeydata, s->rsakeylen);
+
+ /*
+ * Next, set up a shared secret K, of precisely KLEN -
+ * 2*HLEN - 49 bits, where KLEN is the bit length of the
+ * RSA key modulus and HLEN is the bit length of the hash
+ * we're using.
+ */
+ {
+ int klen = ssh_rsakex_klen(s->rsakey);
+ int nbits = klen - (2*ssh->kex->hash->hlen*8 + 49);
+ int i, byte = 0;
+ unsigned char *kstr1, *kstr2, *outstr;
+ int kstr1len, kstr2len, outstrlen;
+
+ s->K = bn_power_2(nbits - 1);
+
+ for (i = 0; i < nbits; i++) {
+ if ((i & 7) == 0) {
+ byte = random_byte();
+ }
+ bignum_set_bit(s->K, i, (byte >> (i & 7)) & 1);
+ }
+
+ /*
+ * Encode this as an mpint.
+ */
+ kstr1 = ssh2_mpint_fmt(s->K, &kstr1len);
+ kstr2 = snewn(kstr2len = 4 + kstr1len, unsigned char);
+ PUT_32BIT(kstr2, kstr1len);
+ memcpy(kstr2 + 4, kstr1, kstr1len);
+
+ /*
+ * Encrypt it with the given RSA key.
+ */
+ outstrlen = (klen + 7) / 8;
+ outstr = snewn(outstrlen, unsigned char);
+ ssh_rsakex_encrypt(ssh->kex->hash, kstr2, kstr2len,
+ outstr, outstrlen, s->rsakey);
+
+ /*
+ * And send it off in a return packet.
+ */
+ s->pktout = ssh2_pkt_init(SSH2_MSG_KEXRSA_SECRET);
+ ssh2_pkt_addstring_start(s->pktout);
+ ssh2_pkt_addstring_data(s->pktout, outstr, outstrlen);
+ ssh2_pkt_send_noqueue(ssh, s->pktout);
+
+ hash_string(ssh->kex->hash, ssh->exhash, outstr, outstrlen);
+
+ sfree(kstr2);
+ sfree(kstr1);
+ sfree(outstr);
+ }
+
+ ssh_rsakex_freekey(s->rsakey);
+
+ crWaitUntil(pktin);
+ if (pktin->type != SSH2_MSG_KEXRSA_DONE) {
+ sfree(s->rsakeydata);
+ bombout(("expected signature packet from server"));
+ crStop(0);
+ }
+
+ ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
+
+ sfree(s->rsakeydata);
+ }
+
hash_mpint(ssh->kex->hash, ssh->exhash, s->K);
assert(ssh->kex->hash->hlen <= sizeof(s->exchange_hash));
ssh->kex->hash->final(ssh->exhash, s->exchange_hash);
- dh_cleanup(ssh->kex_ctx);
ssh->kex_ctx = NULL;
#if 0
dmemdump(s->exchange_hash, ssh->kex->hash->hlen);
#endif
- s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
if (!s->hkey ||
!ssh->hostkey->verifysig(s->hkey, s->sigdata, s->siglen,
(char *)s->exchange_hash,
ssh->sccomp->text_name);
/*
- * Free key exchange data.
+ * Free shared secret.
*/
- freebn(s->f);
freebn(s->K);
- if (!ssh->kex->pdata) {
- freebn(s->g);
- freebn(s->p);
- }
/*
* Key exchange is over. Loop straight back round if we have a
int detect_attack(void *handle, unsigned char *buf, uint32 len,
unsigned char *IV);
+/*
+ * SSH2 RSA key exchange functions
+ */
+struct ssh_hash;
+void *ssh_rsakex_newkey(char *data, int len);
+void ssh_rsakex_freekey(void *key);
+int ssh_rsakex_klen(void *key);
+void ssh_rsakex_encrypt(const struct ssh_hash *h, unsigned char *in, int inlen,
+ unsigned char *out, int outlen,
+ void *key);
+
typedef struct {
uint32 h[4];
} MD5_Core_State;
};
struct ssh_kex {
- /*
- * Plugging in another KEX algorithm requires structural chaos,
- * so it's hard to abstract them into nice little structures
- * like this. Fortunately, all our KEXes are basically
- * Diffie-Hellman at the moment, so in this structure I simply
- * parametrise the DH exchange a bit.
- */
char *name, *groupname;
- const unsigned char *pdata, *gdata;/* NULL means use group exchange */
+ enum { KEXTYPE_DH, KEXTYPE_RSA } main_type;
+ /* For DH */
+ const unsigned char *pdata, *gdata; /* NULL means group exchange */
int plen, glen;
const struct ssh_hash *hash;
};
extern const struct ssh_kexes ssh_diffiehellman_group1;
extern const struct ssh_kexes ssh_diffiehellman_group14;
extern const struct ssh_kexes ssh_diffiehellman_gex;
+extern const struct ssh_kexes ssh_rsa_kex;
extern const struct ssh_signkey ssh_dss;
extern const struct ssh_signkey ssh_rsa;
extern const struct ssh_mac ssh_hmac_md5;
static const struct ssh_kex ssh_diffiehellman_group1_sha1 = {
"diffie-hellman-group1-sha1", "group1",
- P1, G, lenof(P1), lenof(G), &ssh_sha1
+ KEXTYPE_DH, P1, G, lenof(P1), lenof(G), &ssh_sha1
};
static const struct ssh_kex *const group1_list[] = {
static const struct ssh_kex ssh_diffiehellman_group14_sha1 = {
"diffie-hellman-group14-sha1", "group14",
- P14, G, lenof(P14), lenof(G), &ssh_sha1
+ KEXTYPE_DH, P14, G, lenof(P14), lenof(G), &ssh_sha1
};
static const struct ssh_kex *const group14_list[] = {
static const struct ssh_kex ssh_diffiehellman_gex_sha256 = {
"diffie-hellman-group-exchange-sha256", NULL,
- NULL, NULL, 0, 0, &ssh_sha256
+ KEXTYPE_DH, NULL, NULL, 0, 0, &ssh_sha256
};
static const struct ssh_kex ssh_diffiehellman_gex_sha1 = {
"diffie-hellman-group-exchange-sha1", NULL,
- NULL, NULL, 0, 0, &ssh_sha1
+ KEXTYPE_DH, NULL, NULL, 0, 0, &ssh_sha1
};
static const struct ssh_kex *const gex_list[] = {
"ssh-rsa",
"rsa2"
};
+
+void *ssh_rsakex_newkey(char *data, int len)
+{
+ return rsa2_newkey(data, len);
+}
+
+void ssh_rsakex_freekey(void *key)
+{
+ rsa2_freekey(key);
+}
+
+int ssh_rsakex_klen(void *key)
+{
+ struct RSAKey *rsa = (struct RSAKey *) key;
+
+ return bignum_bitcount(rsa->modulus);
+}
+
+static void oaep_mask(const struct ssh_hash *h, void *seed, int seedlen,
+ void *vdata, int datalen)
+{
+ unsigned char *data = (unsigned char *)vdata;
+ unsigned count = 0;
+
+ while (datalen > 0) {
+ int i, max = (datalen > h->hlen ? h->hlen : datalen);
+ void *s;
+ unsigned char counter[4], hash[h->hlen];
+
+ PUT_32BIT(counter, count);
+ s = h->init();
+ h->bytes(s, seed, seedlen);
+ h->bytes(s, counter, 4);
+ h->final(s, hash);
+ count++;
+
+ for (i = 0; i < max; i++)
+ data[i] ^= hash[i];
+
+ data += max;
+ datalen -= max;
+ }
+}
+
+void ssh_rsakex_encrypt(const struct ssh_hash *h, unsigned char *in, int inlen,
+ unsigned char *out, int outlen,
+ void *key)
+{
+ Bignum b1, b2;
+ struct RSAKey *rsa = (struct RSAKey *) key;
+ int k, i;
+ char *p;
+ const int HLEN = h->hlen;
+
+ /*
+ * Here we encrypt using RSAES-OAEP. Essentially this means:
+ *
+ * - we have a SHA-based `mask generation function' which
+ * creates a pseudo-random stream of mask data
+ * deterministically from an input chunk of data.
+ *
+ * - we have a random chunk of data called a seed.
+ *
+ * - we use the seed to generate a mask which we XOR with our
+ * plaintext.
+ *
+ * - then we use _the masked plaintext_ to generate a mask
+ * which we XOR with the seed.
+ *
+ * - then we concatenate the masked seed and the masked
+ * plaintext, and RSA-encrypt that lot.
+ *
+ * The result is that the data input to the encryption function
+ * is random-looking and (hopefully) contains no exploitable
+ * structure such as PKCS1-v1_5 does.
+ *
+ * For a precise specification, see RFC 3447, section 7.1.1.
+ * Some of the variable names below are derived from that, so
+ * it'd probably help to read it anyway.
+ */
+
+ /* k denotes the length in octets of the RSA modulus. */
+ k = (7 + bignum_bitcount(rsa->modulus)) / 8;
+
+ /* The length of the input data must be at most k - 2hLen - 2. */
+ assert(inlen > 0 && inlen <= k - 2*HLEN - 2);
+
+ /* The length of the output data wants to be precisely k. */
+ assert(outlen == k);
+
+ /*
+ * Now perform EME-OAEP encoding. First set up all the unmasked
+ * output data.
+ */
+ /* Leading byte zero. */
+ out[0] = 0;
+ /* At position 1, the seed: HLEN bytes of random data. */
+ for (i = 0; i < HLEN; i++)
+ out[i + 1] = random_byte();
+ /* At position 1+HLEN, the data block DB, consisting of: */
+ /* The hash of the label (we only support an empty label here) */
+ h->final(h->init(), out + HLEN + 1);
+ /* A bunch of zero octets */
+ memset(out + 2*HLEN + 1, 0, outlen - (2*HLEN + 1));
+ /* A single 1 octet, followed by the input message data. */
+ out[outlen - inlen - 1] = 1;
+ memcpy(out + outlen - inlen, in, inlen);
+
+ /*
+ * Now use the seed data to mask the block DB.
+ */
+ oaep_mask(h, out+1, HLEN, out+HLEN+1, outlen-HLEN-1);
+
+ /*
+ * And now use the masked DB to mask the seed itself.
+ */
+ oaep_mask(h, out+HLEN+1, outlen-HLEN-1, out+1, HLEN);
+
+ /*
+ * Now `out' contains precisely the data we want to
+ * RSA-encrypt.
+ */
+ b1 = bignum_from_bytes(out, outlen);
+ b2 = modpow(b1, rsa->exponent, rsa->modulus);
+ p = out;
+ for (i = outlen; i--;) {
+ *p++ = bignum_byte(b2, i);
+ }
+ freebn(b1);
+ freebn(b2);
+
+ /*
+ * And we're done.
+ */
+}
+
+static const struct ssh_kex ssh_rsa_kex_sha1 = {
+ "rsa1024-sha1", NULL, KEXTYPE_RSA, NULL, NULL, 0, 0, &ssh_sha1
+};
+
+static const struct ssh_kex ssh_rsa_kex_sha256 = {
+ "rsa2048-sha256", NULL, KEXTYPE_RSA, NULL, NULL, 0, 0, &ssh_sha256
+};
+
+static const struct ssh_kex *const rsa_kex_list[] = {
+ &ssh_rsa_kex_sha256,
+ &ssh_rsa_kex_sha1
+};
+
+const struct ssh_kexes ssh_rsa_kex = {
+ sizeof(rsa_kex_list) / sizeof(*rsa_kex_list),
+ rsa_kex_list
+};
projects / u / mdw / putty / commitdiff