tor/src/or/hs_descriptor.h

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/* Copyright (c) 2016-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file hs_descriptor.h
* \brief Header file for hs_descriptor.c
**/
#ifndef TOR_HS_DESCRIPTOR_H
#define TOR_HS_DESCRIPTOR_H
#include <stdint.h>
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#include "or.h"
#include "address.h"
#include "container.h"
#include "crypto.h"
#include "crypto_ed25519.h"
#include "torcert.h"
/* Trunnel */
struct link_specifier_t;
/* The earliest descriptor format version we support. */
#define HS_DESC_SUPPORTED_FORMAT_VERSION_MIN 3
/* The latest descriptor format version we support. */
#define HS_DESC_SUPPORTED_FORMAT_VERSION_MAX 3
/* Default lifetime of a descriptor in seconds. The valus is set at 3 hours
* which is 180 minutes or 10800 seconds. */
#define HS_DESC_DEFAULT_LIFETIME (3 * 60 * 60)
/* Maximum lifetime of a descriptor in seconds. The value is set at 12 hours
* which is 720 minutes or 43200 seconds. */
#define HS_DESC_MAX_LIFETIME (12 * 60 * 60)
/* Lifetime of certificate in the descriptor. This defines the lifetime of the
* descriptor signing key and the cross certification cert of that key. It is
* set to 54 hours because a descriptor can be around for 48 hours and because
* consensuses are used after the hour, add an extra 6 hours to give some time
* for the service to stop using it. */
#define HS_DESC_CERT_LIFETIME (54 * 60 * 60)
/* Length of the salt needed for the encrypted section of a descriptor. */
#define HS_DESC_ENCRYPTED_SALT_LEN 16
/* Length of the secret input needed for the KDF construction which derives
* the encryption key for the encrypted data section of the descriptor. This
* adds up to 68 bytes being the blinded key, hashed subcredential and
* revision counter. */
#define HS_DESC_ENCRYPTED_SECRET_INPUT_LEN \
ED25519_PUBKEY_LEN + DIGEST256_LEN + sizeof(uint64_t)
/* Length of the KDF output value which is the length of the secret key,
* the secret IV and MAC key length which is the length of H() output. */
#define HS_DESC_ENCRYPTED_KDF_OUTPUT_LEN \
CIPHER256_KEY_LEN + CIPHER_IV_LEN + DIGEST256_LEN
/* Pad plaintext of superencrypted data section before encryption so that its
* length is a multiple of this value. */
#define HS_DESC_SUPERENC_PLAINTEXT_PAD_MULTIPLE 10000
/* Maximum length in bytes of a full hidden service descriptor. */
#define HS_DESC_MAX_LEN 50000 /* 50kb max size */
/* Key length for the descriptor symmetric encryption. As specified in the
* protocol, we use AES-256 for the encrypted section of the descriptor. The
* following is the length in bytes and the bit size. */
#define HS_DESC_ENCRYPTED_KEY_LEN CIPHER256_KEY_LEN
#define HS_DESC_ENCRYPTED_BIT_SIZE (HS_DESC_ENCRYPTED_KEY_LEN * 8)
/* Type of authentication in the descriptor. */
typedef enum {
HS_DESC_AUTH_ED25519 = 1
} hs_desc_auth_type_t;
/* Link specifier object that contains information on how to extend to the
* relay that is the address, port and handshake type. */
typedef struct hs_desc_link_specifier_t {
/* Indicate the type of link specifier. See trunnel ed25519_cert
* specification. */
uint8_t type;
/* It must be one of these types, can't be more than one. */
union {
/* IP address and port of the relay use to extend. */
tor_addr_port_t ap;
/* Legacy identity. A 20-byte SHA1 identity fingerprint. */
uint8_t legacy_id[DIGEST_LEN];
/* ed25519 identity. A 32-byte key. */
uint8_t ed25519_id[ED25519_PUBKEY_LEN];
} u;
} hs_desc_link_specifier_t;
/* Introduction point information located in a descriptor. */
typedef struct hs_desc_intro_point_t {
/* Link specifier(s) which details how to extend to the relay. This list
* contains hs_desc_link_specifier_t object. It MUST have at least one. */
smartlist_t *link_specifiers;
/* Onion key of the introduction point used to extend to it for the ntor
* handshake. */
curve25519_public_key_t onion_key;
/* Authentication key used to establish the introduction point circuit and
* cross-certifies the blinded public key for the replica thus signed by
* the blinded key and in turn signs it. */
tor_cert_t *auth_key_cert;
/* Encryption key for the "ntor" type. */
curve25519_public_key_t enc_key;
/* Certificate cross certifying the descriptor signing key by the encryption
* curve25519 key. This certificate contains the signing key and is of type
* CERT_TYPE_CROSS_HS_IP_KEYS [0B]. */
tor_cert_t *enc_key_cert;
/* (Optional): If this introduction point is a legacy one that is version <=
* 0.2.9.x (HSIntro=3), we use this extra key for the intro point to be able
* to relay the cells to the service correctly. */
struct {
/* RSA public key. */
crypto_pk_t *key;
/* Cross certified cert with the descriptor signing key (RSA->Ed). Because
* of the cross certification API, we need to keep the certificate binary
* blob and its length in order to properly encode it after. */
struct {
uint8_t *encoded;
size_t len;
} cert;
} legacy;
/* True iff the introduction point has passed the cross certification. Upon
* decoding an intro point, this must be true. */
unsigned int cross_certified : 1;
} hs_desc_intro_point_t;
/* The encrypted data section of a descriptor. Obviously the data in this is
* in plaintext but encrypted once encoded. */
typedef struct hs_desc_encrypted_data_t {
/* Bitfield of CREATE2 cell supported formats. The only currently supported
* format is ntor. */
unsigned int create2_ntor : 1;
/* A list of authentication types that a client must at least support one
* in order to contact the service. Contains NULL terminated strings. */
smartlist_t *intro_auth_types;
/* Is this descriptor a single onion service? */
unsigned int single_onion_service : 1;
/* A list of intro points. Contains hs_desc_intro_point_t objects. */
smartlist_t *intro_points;
} hs_desc_encrypted_data_t;
/* Plaintext data that is unencrypted information of the descriptor. */
typedef struct hs_desc_plaintext_data_t {
/* Version of the descriptor format. Spec specifies this field as a
* positive integer. */
uint32_t version;
/* The lifetime of the descriptor in seconds. */
uint32_t lifetime_sec;
/* Certificate with the short-term ed22519 descriptor signing key for the
* replica which is signed by the blinded public key for that replica. */
tor_cert_t *signing_key_cert;
/* Signing public key which is used to sign the descriptor. Same public key
* as in the signing key certificate. */
ed25519_public_key_t signing_pubkey;
/* Blinded public key used for this descriptor derived from the master
* identity key and generated for a specific replica number. */
ed25519_public_key_t blinded_pubkey;
/* Revision counter is incremented at each upload, regardless of whether
* the descriptor has changed. This avoids leaking whether the descriptor
* has changed. Spec specifies this as a 8 bytes positive integer. */
uint64_t revision_counter;
/* Decoding only: The b64-decoded superencrypted blob from the descriptor */
uint8_t *superencrypted_blob;
/* Decoding only: Size of the superencrypted_blob */
size_t superencrypted_blob_size;
} hs_desc_plaintext_data_t;
/* Service descriptor in its decoded form. */
typedef struct hs_descriptor_t {
/* Contains the plaintext part of the descriptor. */
hs_desc_plaintext_data_t plaintext_data;
/* The following contains what's in the encrypted part of the descriptor.
* It's only encrypted in the encoded version of the descriptor thus the
* data contained in that object is in plaintext. */
hs_desc_encrypted_data_t encrypted_data;
/* Subcredentials of a service, used by the client and service to decrypt
* the encrypted data. */
uint8_t subcredential[DIGEST256_LEN];
} hs_descriptor_t;
/* Return true iff the given descriptor format version is supported. */
static inline int
hs_desc_is_supported_version(uint32_t version)
{
if (version < HS_DESC_SUPPORTED_FORMAT_VERSION_MIN ||
version > HS_DESC_SUPPORTED_FORMAT_VERSION_MAX) {
return 0;
}
return 1;
}
/* Public API. */
void hs_descriptor_free(hs_descriptor_t *desc);
void hs_desc_plaintext_data_free(hs_desc_plaintext_data_t *desc);
void hs_desc_encrypted_data_free(hs_desc_encrypted_data_t *desc);
void hs_desc_link_specifier_free(hs_desc_link_specifier_t *ls);
hs_desc_link_specifier_t *hs_desc_link_specifier_new(
const extend_info_t *info, uint8_t type);
void hs_descriptor_clear_intro_points(hs_descriptor_t *desc);
MOCK_DECL(int,
hs_desc_encode_descriptor,(const hs_descriptor_t *desc,
const ed25519_keypair_t *signing_kp,
char **encoded_out));
int hs_desc_decode_descriptor(const char *encoded,
const uint8_t *subcredential,
hs_descriptor_t **desc_out);
int hs_desc_decode_plaintext(const char *encoded,
hs_desc_plaintext_data_t *plaintext);
int hs_desc_decode_encrypted(const hs_descriptor_t *desc,
hs_desc_encrypted_data_t *desc_out);
size_t hs_desc_obj_size(const hs_descriptor_t *data);
size_t hs_desc_plaintext_obj_size(const hs_desc_plaintext_data_t *data);
hs_desc_intro_point_t *hs_desc_intro_point_new(void);
void hs_desc_intro_point_free(hs_desc_intro_point_t *ip);
link_specifier_t *hs_desc_lspec_to_trunnel(
const hs_desc_link_specifier_t *spec);
#ifdef HS_DESCRIPTOR_PRIVATE
/* Encoding. */
STATIC char *encode_link_specifiers(const smartlist_t *specs);
STATIC size_t build_plaintext_padding(const char *plaintext,
size_t plaintext_len,
uint8_t **padded_out);
/* Decoding. */
STATIC smartlist_t *decode_link_specifiers(const char *encoded);
STATIC hs_desc_intro_point_t *decode_introduction_point(
const hs_descriptor_t *desc,
const char *text);
STATIC int encrypted_data_length_is_valid(size_t len);
STATIC int cert_is_valid(tor_cert_t *cert, uint8_t type,
const char *log_obj_type);
STATIC int desc_sig_is_valid(const char *b64_sig,
const ed25519_public_key_t *signing_pubkey,
const char *encoded_desc, size_t encoded_len);
STATIC size_t decode_superencrypted(const char *message, size_t message_len,
uint8_t **encrypted_out);
STATIC void desc_plaintext_data_free_contents(hs_desc_plaintext_data_t *desc);
MOCK_DECL(STATIC size_t, decrypt_desc_layer,(const hs_descriptor_t *desc,
const uint8_t *encrypted_blob,
size_t encrypted_blob_size,
int is_superencrypted_layer,
char **decrypted_out));
#endif /* defined(HS_DESCRIPTOR_PRIVATE) */
#endif /* !defined(TOR_HS_DESCRIPTOR_H) */