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;
    }

    {
	EVP_CIPHER_CTX rc4_key;

	EVP_CIPHER_CTX_init(&rc4_key);
	EVP_CipherInit_ex(&rc4_key, EVP_rc4(), NULL, k6_data, NULL, 1);
	EVP_Cipher(&rc4_key, SND_SEQ, p0 + 8, 8);
	EVP_CIPHER_CTX_cleanup(&rc4_key);
	memset(k6_data, 0, sizeof(k6_data));
    }

    _gss_mg_decode_be_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) {
	EVP_CIPHER_CTX rc4_key;

	EVP_CIPHER_CTX_init(&rc4_key);
	EVP_CipherInit_ex(&rc4_key, EVP_rc4(), NULL, k6_data, NULL, 1);
	EVP_Cipher(&rc4_key, Confounder, p0 + 24, 8);
	EVP_Cipher(&rc4_key, output_message_buffer->value, p0 + GSS_ARCFOUR_WRAP_TOKEN_SIZE, datalen);
	EVP_CIPHER_CTX_cleanup(&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 = ct_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->gk5c.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;
}
OM_uint32
_gssapi_wrap_arcfour(OM_uint32 * minor_status,
		     const gsskrb5_ctx context_handle,
		     krb5_context context,
		     int conf_req_flag,
		     gss_qop_t qop_req,
		     const gss_buffer_t input_message_buffer,
		     int * conf_state,
		     gss_buffer_t output_message_buffer,
		     krb5_keyblock *key)
{
    u_char Klocaldata[16], k6_data[16], *p, *p0;
    size_t len, total_len, datalen;
    krb5_keyblock Klocal;
    krb5_error_code ret;
    int32_t seq_number;

    if (conf_state)
	*conf_state = 0;

    datalen = input_message_buffer->length;

    if (IS_DCE_STYLE(context_handle)) {
	len = GSS_ARCFOUR_WRAP_TOKEN_SIZE;
	_gssapi_encap_length(len, &len, &total_len, GSS_KRB5_MECHANISM);
	total_len += datalen;
    } else {
	datalen += 1; /* padding */
	len = datalen + GSS_ARCFOUR_WRAP_TOKEN_SIZE;
	_gssapi_encap_length(len, &len, &total_len, GSS_KRB5_MECHANISM);
    }

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

    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);

    _gss_mg_encode_be_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) {
	EVP_CIPHER_CTX rc4_key;

	EVP_CIPHER_CTX_init(&rc4_key);
	EVP_CipherInit_ex(&rc4_key, EVP_rc4(), NULL, k6_data, NULL, 1);
	EVP_Cipher(&rc4_key, p0 + 24, p0 + 24, 8 + datalen);
	EVP_CIPHER_CTX_cleanup(&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;
    }

    {
	EVP_CIPHER_CTX rc4_key;

	EVP_CIPHER_CTX_init(&rc4_key);
	EVP_CipherInit_ex(&rc4_key, EVP_rc4(), NULL, k6_data, NULL, 1);
	EVP_Cipher(&rc4_key, p0 + 8, p0 + 8 /* SND_SEQ */, 8);
	EVP_CIPHER_CTX_cleanup(&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_verify_mic_arcfour(OM_uint32 * minor_status,
			   const gsskrb5_ctx context_handle,
			   krb5_context context,
			   const gss_buffer_t message_buffer,
			   const gss_buffer_t token_buffer,
			   gss_qop_t * qop_state,
			   krb5_keyblock *key,
			   const char *type)
{
    krb5_error_code ret;
    uint32_t seq_number;
    OM_uint32 omret;
    u_char SND_SEQ[8], cksum_data[8], *p;
    char k6_data[16];
    int cmp;

    if (qop_state)
	*qop_state = 0;

    p = token_buffer->value;
    omret = _gsskrb5_verify_header (&p,
				       token_buffer->length,
				       type,
				       GSS_KRB5_MECHANISM);
    if (omret)
	return omret;

    if (memcmp(p, "\x11\x00", 2) != 0) /* SGN_ALG = HMAC MD5 ARCFOUR */
	return GSS_S_BAD_SIG;
    p += 2;
    if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
	return GSS_S_BAD_MIC;
    p += 4;

    ret = arcfour_mic_cksum(context,
			    key, KRB5_KU_USAGE_SIGN,
			    cksum_data, sizeof(cksum_data),
			    p - 8, 8,
			    message_buffer->value, message_buffer->length,
			    NULL, 0);
    if (ret) {
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    ret = arcfour_mic_key(context, key,
			  cksum_data, sizeof(cksum_data),
			  k6_data, sizeof(k6_data));
    if (ret) {
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    cmp = ct_memcmp(cksum_data, p + 8, 8);
    if (cmp) {
	*minor_status = 0;
	return GSS_S_BAD_MIC;
    }

    {
	EVP_CIPHER_CTX rc4_key;

	EVP_CIPHER_CTX_init(&rc4_key);
	EVP_CipherInit_ex(&rc4_key, EVP_rc4(), NULL, (void *)k6_data, NULL, 0);
	EVP_Cipher(&rc4_key, SND_SEQ, p, 8);
	EVP_CIPHER_CTX_cleanup(&rc4_key);

	memset(k6_data, 0, sizeof(k6_data));
    }

    _gss_mg_decode_be_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);

    memset(SND_SEQ, 0, sizeof(SND_SEQ));
    if (cmp != 0) {
	*minor_status = 0;
	return GSS_S_BAD_MIC;
    }

    HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
    omret = _gssapi_msg_order_check(context_handle->gk5c.order, seq_number);
    HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
    if (omret)
	return omret;

    *minor_status = 0;
    return GSS_S_COMPLETE;
}
OM_uint32
_gssapi_get_mic_arcfour(OM_uint32 * minor_status,
			const gsskrb5_ctx context_handle,
			krb5_context context,
			gss_qop_t qop_req,
			const gss_buffer_t message_buffer,
			gss_buffer_t message_token,
			krb5_keyblock *key)
{
    krb5_error_code ret;
    int32_t seq_number;
    size_t len, total_len;
    u_char k6_data[16], *p0, *p;
    EVP_CIPHER_CTX rc4_key;

    _gsskrb5_encap_length (22, &len, &total_len, GSS_KRB5_MECHANISM);

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

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

    *p++ = 0x01; /* TOK_ID */
    *p++ = 0x01;
    *p++ = 0x11; /* SGN_ALG */
    *p++ = 0x00;
    *p++ = 0xff; /* Filler */
    *p++ = 0xff;
    *p++ = 0xff;
    *p++ = 0xff;

    p = NULL;

    ret = arcfour_mic_cksum(context,
			    key, KRB5_KU_USAGE_SIGN,
			    p0 + 16, 8,  /* SGN_CKSUM */
			    p0, 8, /* TOK_ID, SGN_ALG, Filer */
			    message_buffer->value, message_buffer->length,
			    NULL, 0);
    if (ret) {
	_gsskrb5_release_buffer(minor_status, message_token);
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

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

    HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
    krb5_auth_con_getlocalseqnumber (context,
				     context_handle->auth_context,
				     &seq_number);
    p = p0 + 8; /* SND_SEQ */
    _gss_mg_encode_be_uint32(seq_number, p);

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

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

    EVP_CIPHER_CTX_init(&rc4_key);
    EVP_CipherInit_ex(&rc4_key, EVP_rc4(), NULL, k6_data, NULL, 1);
    EVP_Cipher(&rc4_key, p, p, 8);
    EVP_CIPHER_CTX_cleanup(&rc4_key);

    memset(k6_data, 0, sizeof(k6_data));

    *minor_status = 0;
    return GSS_S_COMPLETE;
}
示例#5
0
OM_uint32 _gssapi_unwrap_arcfour(OM_uint32 *minor_status,
				 const gss_ctx_id_t context_handle,
				 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;
    int32_t seq_number;
    size_t datalen;
    OM_uint32 omret;
    char k6_data[16], SND_SEQ[8], Confounder[8];
    char cksum_data[8];
    u_char *p, *p0;
    int cmp;
    int conf_flag;
    size_t padlen;
    
    if (conf_state)
	*conf_state = 0;
    if (qop_state)
	*qop_state = 0;

    p0 = input_message_buffer->value;
    omret = _gssapi_verify_mech_header(&p0,
				       input_message_buffer->length,
				       GSS_KRB5_MECHANISM);
    if (omret)
	return omret;
    p = p0;

    datalen = input_message_buffer->length -
	(p - ((u_char *)input_message_buffer->value)) - 
	GSS_ARCFOUR_WRAP_TOKEN_SIZE;

    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(gssapi_krb5_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));
    }

    gssapi_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(gssapi_krb5_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));

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

    ret = arcfour_mic_cksum(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) {
	gss_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) {
	gss_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;
}
示例#6
0
OM_uint32
_gssapi_verify_mic_arcfour(OM_uint32 * minor_status,
			   const gss_ctx_id_t context_handle,
			   const gss_buffer_t message_buffer,
			   const gss_buffer_t token_buffer,
			   gss_qop_t * qop_state,
			   krb5_keyblock *key,
			   char *type)
{
    krb5_error_code ret;
    int32_t seq_number;
    OM_uint32 omret;
    char cksum_data[8], k6_data[16], SND_SEQ[8];
    u_char *p;
    int cmp;
    
    if (qop_state)
	*qop_state = 0;

    p = token_buffer->value;
    omret = gssapi_krb5_verify_header (&p,
				       token_buffer->length,
				       type,
				       GSS_KRB5_MECHANISM);
    if (omret)
	return omret;
    
    if (memcmp(p, "\x11\x00", 2) != 0) /* SGN_ALG = HMAC MD5 ARCFOUR */
	return GSS_S_BAD_SIG;
    p += 2;
    if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
	return GSS_S_BAD_MIC;
    p += 4;

    ret = arcfour_mic_cksum(key, KRB5_KU_USAGE_SIGN,
			    cksum_data, sizeof(cksum_data),
			    p - 8, 8,
			    message_buffer->value, message_buffer->length,
			    NULL, 0);
    if (ret) {
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    ret = arcfour_mic_key(gssapi_krb5_context, key,
			  cksum_data, sizeof(cksum_data),
			  k6_data, sizeof(k6_data));
    if (ret) {
	*minor_status = ret;
	return GSS_S_FAILURE;
    }

    cmp = memcmp(cksum_data, p + 8, 8);
    if (cmp) {
	*minor_status = 0;
	return GSS_S_BAD_MIC;
    }

    {
	RC4_KEY rc4_key;
	
	RC4_set_key (&rc4_key, sizeof(k6_data), k6_data);
	RC4 (&rc4_key, 8, p, SND_SEQ);
	
	memset(&rc4_key, 0, sizeof(rc4_key));
	memset(k6_data, 0, sizeof(k6_data));
    }

    gssapi_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);

    memset(SND_SEQ, 0, sizeof(SND_SEQ));
    if (cmp != 0) {
	*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;

    *minor_status = 0;
    return GSS_S_COMPLETE;
}