arcfour.c

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    p0 = _gssapi_make_mech_header(output_message_buffer->value,
				  len,
				  GSS_KRB5_MECHANISM);
    p = p0;

    *p++ = 0x02; /* TOK_ID */
    *p++ = 0x01;
    *p++ = 0x11; /* SGN_ALG */
    *p++ = 0x00;
    if (conf_req_flag) {
	*p++ = 0x10; /* SEAL_ALG */
	*p++ = 0x00;
    } else {
	*p++ = 0xff; /* SEAL_ALG */
	*p++ = 0xff;
    }
    *p++ = 0xff; /* Filler */
    *p++ = 0xff;

    p = NULL;

    HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
    krb5_auth_con_getlocalseqnumber (context,
				     context_handle->auth_context,
				     &seq_number);

    _gsskrb5_encode_be_om_uint32(seq_number, p0 + 8);

    krb5_auth_con_setlocalseqnumber (context,
				     context_handle->auth_context,
				     ++seq_number);
    HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);

    memset (p0 + 8 + 4,
	    (context_handle->more_flags & LOCAL) ? 0 : 0xff,
	    4);

    krb5_generate_random_block(p0 + 24, 8); /* fill in Confounder */
    
    /* p points to data */
    p = p0 + GSS_ARCFOUR_WRAP_TOKEN_SIZE;
    memcpy(p, input_message_buffer->value, input_message_buffer->length);

    if (!IS_DCE_STYLE(context_handle))
	p[input_message_buffer->length] = 1; /* padding */

    ret = arcfour_mic_cksum(context,
			    key, KRB5_KU_USAGE_SEAL,
			    p0 + 16, 8, /* SGN_CKSUM */ 
			    p0, 8, /* TOK_ID, SGN_ALG, SEAL_ALG, Filler */
			    p0 + 24, 8, /* Confounder */
			    p0 + GSS_ARCFOUR_WRAP_TOKEN_SIZE, 
			    datalen);
    if (ret) {
	*minor_status = ret;
	_gsskrb5_release_buffer(minor_status, output_message_buffer);
	return GSS_S_FAILURE;
    }

    {
	int i;

	Klocal.keytype = key->keytype;
	Klocal.keyvalue.data = Klocaldata;
	Klocal.keyvalue.length = sizeof(Klocaldata);

	for (i = 0; i < 16; i++)
	    Klocaldata[i] = ((u_char *)key->keyvalue.data)[i] ^ 0xF0;
    }
    ret = arcfour_mic_key(context, &Klocal,
			  p0 + 8, 4, /* SND_SEQ */
			  k6_data, sizeof(k6_data));
    memset(Klocaldata, 0, sizeof(Klocaldata));
    if (ret) {
	_gsskrb5_release_buffer(minor_status, output_message_buffer);
	*minor_status = ret;
	return GSS_S_FAILURE;
    }


    if(conf_req_flag) {
	RC4_KEY rc4_key;

	RC4_set_key (&rc4_key, sizeof(k6_data), (void *)k6_data);
	/* XXX ? */
	RC4 (&rc4_key, 8 + datalen, p0 + 24, p0 + 24); /* Confounder + data */
	memset(&rc4_key, 0, sizeof(rc4_key));
    }
    memset(k6_data, 0, sizeof(k6_data));

    ret = arcfour_mic_key(context, key,
			  p0 + 16, 8, /* SGN_CKSUM */
			  k6_data, sizeof(k6_data));
    if (ret) {
	_gsskrb5_release_buffer(minor_status, output_message_buffer);
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    {
	RC4_KEY rc4_key;
	
	RC4_set_key (&rc4_key, sizeof(k6_data), k6_data);
	RC4 (&rc4_key, 8, p0 + 8, p0 + 8); /* SND_SEQ */
	memset(&rc4_key, 0, sizeof(rc4_key));
	memset(k6_data, 0, sizeof(k6_data));
    }

    if (conf_state)
	*conf_state = conf_req_flag;

    *minor_status = 0;
    return GSS_S_COMPLETE;
}

OM_uint32 _gssapi_unwrap_arcfour(OM_uint32 *minor_status,
				 const gsskrb5_ctx context_handle,
				 krb5_context context,
				 const gss_buffer_t input_message_buffer,
				 gss_buffer_t output_message_buffer,
				 int *conf_state,
				 gss_qop_t *qop_state,
				 krb5_keyblock *key)
{
    u_char Klocaldata[16];
    krb5_keyblock Klocal;
    krb5_error_code ret;
    uint32_t seq_number;
    size_t datalen;
    OM_uint32 omret;
    u_char k6_data[16], SND_SEQ[8], Confounder[8];
    u_char cksum_data[8];
    u_char *p, *p0;
    int cmp;
    int conf_flag;
    size_t padlen = 0, len;
    
    if (conf_state)
	*conf_state = 0;
    if (qop_state)
	*qop_state = 0;

    p0 = input_message_buffer->value;

    if (IS_DCE_STYLE(context_handle)) {
	len = GSS_ARCFOUR_WRAP_TOKEN_SIZE + 
	    GSS_ARCFOUR_WRAP_TOKEN_DCE_DER_HEADER_SIZE;
	if (input_message_buffer->length < len)
	    return GSS_S_BAD_MECH;
    } else {
	len = input_message_buffer->length;
    }

    omret = _gssapi_verify_mech_header(&p0,
				       len,
				       GSS_KRB5_MECHANISM);
    if (omret)
	return omret;

    /* length of mech header */
    len = (p0 - (u_char *)input_message_buffer->value) + 
	GSS_ARCFOUR_WRAP_TOKEN_SIZE;

    if (len > input_message_buffer->length)
	return GSS_S_BAD_MECH;

    /* length of data */
    datalen = input_message_buffer->length - len;

    p = p0;

    if (memcmp(p, "\x02\x01", 2) != 0)
	return GSS_S_BAD_SIG;
    p += 2;
    if (memcmp(p, "\x11\x00", 2) != 0) /* SGN_ALG = HMAC MD5 ARCFOUR */
	return GSS_S_BAD_SIG;
    p += 2;

    if (memcmp (p, "\x10\x00", 2) == 0)
	conf_flag = 1;
    else if (memcmp (p, "\xff\xff", 2) == 0)
	conf_flag = 0;
    else
	return GSS_S_BAD_SIG;

    p += 2;
    if (memcmp (p, "\xff\xff", 2) != 0)
	return GSS_S_BAD_MIC;
    p = NULL;

    ret = arcfour_mic_key(context, key,
			  p0 + 16, 8, /* SGN_CKSUM */
			  k6_data, sizeof(k6_data));
    if (ret) {
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    {
	RC4_KEY rc4_key;
	
	RC4_set_key (&rc4_key, sizeof(k6_data), k6_data);
	RC4 (&rc4_key, 8, p0 + 8, SND_SEQ); /* SND_SEQ */
	memset(&rc4_key, 0, sizeof(rc4_key));
	memset(k6_data, 0, sizeof(k6_data));
    }

    _gsskrb5_decode_be_om_uint32(SND_SEQ, &seq_number);

    if (context_handle->more_flags & LOCAL)
	cmp = memcmp(&SND_SEQ[4], "\xff\xff\xff\xff", 4);
    else
	cmp = memcmp(&SND_SEQ[4], "\x00\x00\x00\x00", 4);

    if (cmp != 0) {
	*minor_status = 0;
	return GSS_S_BAD_MIC;
    }

    {
	int i;

	Klocal.keytype = key->keytype;
	Klocal.keyvalue.data = Klocaldata;
	Klocal.keyvalue.length = sizeof(Klocaldata);

	for (i = 0; i < 16; i++)
	    Klocaldata[i] = ((u_char *)key->keyvalue.data)[i] ^ 0xF0;
    }
    ret = arcfour_mic_key(context, &Klocal,
			  SND_SEQ, 4,
			  k6_data, sizeof(k6_data));
    memset(Klocaldata, 0, sizeof(Klocaldata));
    if (ret) {
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    output_message_buffer->value = malloc(datalen);
    if (output_message_buffer->value == NULL) {
	*minor_status = ENOMEM;
	return GSS_S_FAILURE;
    }
    output_message_buffer->length = datalen;

    if(conf_flag) {
	RC4_KEY rc4_key;

	RC4_set_key (&rc4_key, sizeof(k6_data), k6_data);
	RC4 (&rc4_key, 8, p0 + 24, Confounder); /* Confounder */
	RC4 (&rc4_key, datalen, p0 + GSS_ARCFOUR_WRAP_TOKEN_SIZE,
	     output_message_buffer->value);
	memset(&rc4_key, 0, sizeof(rc4_key));
    } else {
	memcpy(Confounder, p0 + 24, 8); /* Confounder */
	memcpy(output_message_buffer->value, 
	       p0 + GSS_ARCFOUR_WRAP_TOKEN_SIZE,
	       datalen);
    }
    memset(k6_data, 0, sizeof(k6_data));

    if (!IS_DCE_STYLE(context_handle)) {
	ret = _gssapi_verify_pad(output_message_buffer, datalen, &padlen);
	if (ret) {
	    _gsskrb5_release_buffer(minor_status, output_message_buffer);
	    *minor_status = 0;
	    return ret;
	}
	output_message_buffer->length -= padlen;
    }

    ret = arcfour_mic_cksum(context,
			    key, KRB5_KU_USAGE_SEAL,
			    cksum_data, sizeof(cksum_data),
			    p0, 8, 
			    Confounder, sizeof(Confounder),
			    output_message_buffer->value, 
			    output_message_buffer->length + padlen);
    if (ret) {
	_gsskrb5_release_buffer(minor_status, output_message_buffer);
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    cmp = memcmp(cksum_data, p0 + 16, 8); /* SGN_CKSUM */
    if (cmp) {
	_gsskrb5_release_buffer(minor_status, output_message_buffer);
	*minor_status = 0;
	return GSS_S_BAD_MIC;
    }

    HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
    omret = _gssapi_msg_order_check(context_handle->order, seq_number);
    HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
    if (omret)
	return omret;

    if (conf_state)
	*conf_state = conf_flag;

    *minor_status = 0;
    return GSS_S_COMPLETE;
}

static OM_uint32
max_wrap_length_arcfour(const gsskrb5_ctx ctx,
			krb5_crypto crypto,
			size_t input_length,
			OM_uint32 *max_input_size)
{
    /* 
     * if GSS_C_DCE_STYLE is in use:
     *  - we only need to encapsulate the WRAP token
     * However, since this is a fixed since, we just 
     */
    if (IS_DCE_STYLE(ctx)) {
	size_t len, total_len;

	len = GSS_ARCFOUR_WRAP_TOKEN_SIZE;
	_gssapi_encap_length(len, &len, &total_len, GSS_KRB5_MECHANISM);

	if (input_length < len)
	    *max_input_size = 0;
	else
	    *max_input_size = input_length - len;

    } else {
	size_t extrasize = GSS_ARCFOUR_WRAP_TOKEN_SIZE;
	size_t blocksize = 8;
	size_t len, total_len;

	len = 8 + input_length + blocksize + extrasize;

	_gsskrb5_encap_length(len, &len, &total_len, GSS_KRB5_MECHANISM);

	total_len -= input_length; /* token length */
	if (total_len < input_length) {
	    *max_input_size = (input_length - total_len);
	    (*max_input_size) &= (~(OM_uint32)(blocksize - 1));
	} else {
	    *max_input_size = 0;
	}
    }

    return GSS_S_COMPLETE;
}

OM_uint32
_gssapi_wrap_size_arcfour(OM_uint32 *minor_status,
			  const gsskrb5_ctx ctx,
			  krb5_context context,
			  int conf_req_flag,
			  gss_qop_t qop_req,
			  OM_uint32 req_output_size,
			  OM_uint32 *max_input_size,
			  krb5_keyblock *key)
{
    krb5_error_code ret;
    krb5_crypto crypto;

    ret = krb5_crypto_init(context, key, 0, &crypto);
    if (ret != 0) {
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    ret = max_wrap_length_arcfour(ctx, crypto,
				  req_output_size, max_input_size);
    if (ret != 0) {
	*minor_status = ret;
	krb5_crypto_destroy(context, crypto);
	return GSS_S_FAILURE;
    }

    krb5_crypto_destroy(context, crypto);

    return GSS_S_COMPLETE;
}