* Handle the key exchange and user authentication phases.
 */
static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
			 struct Packet *pktin)
{
    int i, j, ret;
    unsigned char cookie[8], *ptr;

    struct MD5Context md5c;
    struct do_ssh1_login_state {
	int crLine;
	int len;
	unsigned char *rsabuf, *keystr1, *keystr2;
	unsigned long supported_ciphers_mask, supported_auths_mask;
	int tried_publickey, tried_agent;

	int authed;
	struct RSAKey key;
	Bignum challenge;
	char *commentp;
	int commentlen;
        int dlgret;
	Filename *keyfile;
        struct RSAKey servkey, hostkey;
    };
    crState(do_ssh1_login_state);

    crBeginState;

    if (!pktin)
	crWaitUntil(pktin);

    ptr = ssh_pkt_getdata(pktin, 8);
    if (!ptr) {
	bombout(("SSH-1 public key packet stopped before random cookie"));
	crStop(0);
    }
    memcpy(cookie, ptr, 8);

    if (!ssh1_pkt_getrsakey(pktin, &s->servkey, &s->keystr1) ||
	!ssh1_pkt_getrsakey(pktin, &s->hostkey, &s->keystr2)) {	
	bombout(("Failed to read SSH-1 public keys from public key packet"));
	crStop(0);
    }

    /*
     * Log the host key fingerprint.
     */
    {
	char logmsg[80];
	logevent("Host key fingerprint is:");
	strcpy(logmsg, "      ");
	s->hostkey.comment = NULL;
	rsa_fingerprint(logmsg + strlen(logmsg),
			sizeof(logmsg) - strlen(logmsg), &s->hostkey);
	logevent(logmsg);
    }

    ssh->v1_remote_protoflags = ssh_pkt_getuint32(pktin);
    s->supported_ciphers_mask = ssh_pkt_getuint32(pktin);
    s->supported_auths_mask = ssh_pkt_getuint32(pktin);
    if ((ssh->remote_bugs & BUG_CHOKES_ON_RSA))
	s->supported_auths_mask &= ~(1 << SSH1_AUTH_RSA);

    ssh->v1_local_protoflags =
	ssh->v1_remote_protoflags & SSH1_PROTOFLAGS_SUPPORTED;
    ssh->v1_local_protoflags |= SSH1_PROTOFLAG_SCREEN_NUMBER;

    MD5Init(&md5c);
    MD5Update(&md5c, s->keystr2, s->hostkey.bytes);
    MD5Update(&md5c, s->keystr1, s->servkey.bytes);
    MD5Update(&md5c, cookie, 8);
    MD5Final(s->session_id, &md5c);

    for (i = 0; i < 32; i++)
	ssh->session_key[i] = random_byte();

    /*
     * Verify that the `bits' and `bytes' parameters match.
     */
    if (s->hostkey.bits > s->hostkey.bytes * 8 ||
	s->servkey.bits > s->servkey.bytes * 8) {
	bombout(("SSH-1 public keys were badly formatted"));
	crStop(0);
    }

    s->len = (s->hostkey.bytes > s->servkey.bytes ?
              s->hostkey.bytes : s->servkey.bytes);

    s->rsabuf = snewn(s->len, unsigned char);

    /*
     * Verify the host key.
     */
    {
	/*
	 * First format the key into a string.
	 */
	int len = rsastr_len(&s->hostkey);
	char fingerprint[100];
	char *keystr = snewn(len, char);
	rsastr_fmt(keystr, &s->hostkey);
	rsa_fingerprint(fingerprint, sizeof(fingerprint), &s->hostkey);

        ssh_set_frozen(ssh, 1);
	s->dlgret = verify_ssh_host_key(ssh->frontend,
                                        ssh->savedhost, ssh->savedport,
                                        "rsa", keystr, fingerprint,
                                        ssh_dialog_callback, ssh);
	sfree(keystr);

    for (i = 0; i < 32; i++) {
	s->rsabuf[i] = ssh->session_key[i];
	if (i < 16)
	    s->rsabuf[i] ^= s->session_id[i];
    }

    if (s->hostkey.bytes > s->servkey.bytes) {
	ret = rsaencrypt(s->rsabuf, 32, &s->servkey);
	if (ret)
	    ret = rsaencrypt(s->rsabuf, s->servkey.bytes, &s->hostkey);
    } else {
	ret = rsaencrypt(s->rsabuf, 32, &s->hostkey);
	if (ret)
	    ret = rsaencrypt(s->rsabuf, s->hostkey.bytes, &s->servkey);
    }
    if (!ret) {
	bombout(("SSH-1 public key encryptions failed due to bad formatting"));
	crStop(0);	
    }

    logevent("Encrypted session key");

    ssh->v1_cipher_ctx = ssh->cipher->make_context();
    ssh->cipher->sesskey(ssh->v1_cipher_ctx, ssh->session_key);
    logeventf(ssh, "Initialised %s encryption", ssh->cipher->text_name);

    ssh->crcda_ctx = crcda_make_context();
    logevent("Installing CRC compensation attack detector");

    if (s->servkey.modulus) {
	sfree(s->servkey.modulus);
	s->servkey.modulus = NULL;
    }
    if (s->servkey.exponent) {
	sfree(s->servkey.exponent);
	s->servkey.exponent = NULL;
    }
    if (s->hostkey.modulus) {
	sfree(s->hostkey.modulus);
	s->hostkey.modulus = NULL;
    }
    if (s->hostkey.exponent) {
	sfree(s->hostkey.exponent);
	s->hostkey.exponent = NULL;
    }
    crWaitUntil(pktin);

    if (pktin->type != SSH1_SMSG_SUCCESS) {
	bombout(("Encryption not successfully enabled"));
	crStop(0);
    }