torcert.c File Reference

Implementation for ed25519-signed certificates as used in the Tor protocol. More...

#include "core/or/or.h"
#include "app/config/config.h"
#include "lib/crypt_ops/crypto_util.h"
#include "feature/nodelist/torcert.h"
#include "trunnel/ed25519_cert.h"
#include "lib/log/log.h"
#include "trunnel/link_handshake.h"
#include "lib/tls/tortls.h"
#include "lib/tls/x509.h"
#include "core/or/or_handshake_certs_st.h"

Go to the source code of this file.

Macros
#define	RSA_ED_CROSSCERT_PREFIX   "Tor TLS RSA/Ed25519 cross-certificate"
#define	ERR(code, s)
#define	ERR(s)
#define	ADDCERT(cert, pk)

Functions
tor_cert_t *	tor_cert_create_raw (const ed25519_keypair_t *signing_key, uint8_t cert_type, uint8_t signed_key_type, const uint8_t signed_key_info[32], time_t now, time_t lifetime, uint32_t flags)
tor_cert_t *	tor_cert_create_ed25519 (const ed25519_keypair_t *signing_key, uint8_t cert_type, const ed25519_public_key_t *signed_key, time_t now, time_t lifetime, uint32_t flags)
void	tor_cert_free_ (tor_cert_t *cert)
tor_cert_t *	tor_cert_parse (const uint8_t *encoded, const size_t len)
int	tor_cert_get_checkable_sig (ed25519_checkable_t *checkable_out, const tor_cert_t *cert, const ed25519_public_key_t *pubkey, time_t *expiration_out)
int	tor_cert_checksig (tor_cert_t *cert, const ed25519_public_key_t *pubkey, time_t now)
const char *	tor_cert_describe_signature_status (const tor_cert_t *cert)
tor_cert_t *	tor_cert_dup (const tor_cert_t *cert)
int	tor_cert_eq (const tor_cert_t *cert1, const tor_cert_t *cert2)
int	tor_cert_opt_eq (const tor_cert_t *cert1, const tor_cert_t *cert2)
ssize_t	tor_make_rsa_ed25519_crosscert (const ed25519_public_key_t *ed_key, const crypto_pk_t *rsa_key, time_t expires, uint8_t **cert)
int	rsa_ed25519_crosscert_check (const uint8_t *crosscert, const size_t crosscert_len, const crypto_pk_t *rsa_id_key, const ed25519_public_key_t *master_key, const time_t reject_if_expired_before)
or_handshake_certs_t *	or_handshake_certs_new (void)
void	or_handshake_certs_free_ (or_handshake_certs_t *certs)
int	or_handshake_certs_rsa_ok (int severity, or_handshake_certs_t *certs, tor_tls_t *tls, time_t now)
int	or_handshake_certs_ed25519_ok (int severity, or_handshake_certs_t *certs, tor_tls_t *tls, time_t now)
int	check_tap_onion_key_crosscert (const uint8_t *crosscert, int crosscert_len, const crypto_pk_t *onion_pkey, const ed25519_public_key_t *master_id_pkey, const uint8_t *rsa_id_digest)
void	or_handshake_certs_check_both (int severity, or_handshake_certs_t *certs, tor_tls_t *tls, time_t now, const ed25519_public_key_t **ed_id_out, const common_digests_t **rsa_id_out)
int	tor_cert_encode_ed22519 (const tor_cert_t *cert, char **cert_str_out)

Detailed Description

Implementation for ed25519-signed certificates as used in the Tor protocol.

This certificate format is designed to be simple and compact; it's documented in tor-spec.txt in the torspec.git repository. All of the certificates in this format are signed with an Ed25519 key; the contents themselves may be another Ed25519 key, a digest of a RSA key, or some other material.

In this module there is also support for a crooss-certification of Ed25519 identities using (older) RSA1024 identities.

Tor uses other types of certificate too, beyond those described in this module. Notably, our use of TLS requires us to touch X.509 certificates, even though sensible people would stay away from those. Our X.509 certificates are represented with tor_x509_cert_t, and implemented in tortls.c. We also have a separate certificate type that authorities use to authenticate their RSA signing keys with their RSA identity keys: that one is authority_cert_t, and it's mostly handled in routerlist.c.

Definition in file torcert.c.

Macro Definition Documentation

ADDCERT

#define ADDCERT	(		cert,
			pk
	)

Value:

  do {                                                                  \
    tor_assert(n_checkable < ARRAY_LENGTH(check));                      \
    if (tor_cert_get_checkable_sig(&check[n_checkable++], cert, pk,     \
                                   &expiration) < 0)                    \
      ERR("Could not get checkable cert.");                             \
  } while (0)

ERR [1/2]

#define ERR	(		code,
			s
	)

Value:

  do {                                                          \
    log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,                      \
           "Received a bad RSA->Ed25519 crosscert: %s",         \
           (s));                                                \
    rv = (code);                                                \
    goto err;                                                   \
  } while (0)

Definition at line 497 of file torcert.c.

ERR [2/2]

#define ERR

(

s

)

Value:

  do {                                                          \
    log_fn(severity, LD_PROTOCOL,                               \
           "Received a bad CERTS cell: %s",                     \
           (s));                                                \
    return 0;                                                   \
  } while (0)

Definition at line 497 of file torcert.c.

Function Documentation

check_tap_onion_key_crosscert()

int check_tap_onion_key_crosscert	(	const uint8_t *	crosscert,
		int	crosscert_len,
		const crypto_pk_t *	onion_pkey,
		const ed25519_public_key_t *	master_id_pkey,
		const uint8_t *	rsa_id_digest
	)

Check whether an RSA-TAP cross-certification is correct. Return 0 if it is, -1 if it isn't.

Definition at line 649 of file torcert.c.

or_handshake_certs_check_both()

void or_handshake_certs_check_both	(	int	severity,
		or_handshake_certs_t *	certs,
		tor_tls_t *	tls,
		time_t	now,
		const ed25519_public_key_t **	ed_id_out,
		const common_digests_t **	rsa_id_out
	)

Check the Ed certificates and/or the RSA certificates, as appropriate. If we obtained an Ed25519 identity, set *ed_id_out. If we obtained an RSA identity, set *rs_id_out. Otherwise, set them both to NULL.

Definition at line 685 of file torcert.c.

or_handshake_certs_ed25519_ok()

int or_handshake_certs_ed25519_ok	(	int	severity,
		or_handshake_certs_t *	certs,
		tor_tls_t *	tls,
		time_t	now
	)

Check all the ed25519 certificates in certs against each other, and against the peer certificate in tls if appropriate. On success, return 0; on failure, return a negative value and warn at level severity

Definition at line 541 of file torcert.c.

Referenced by or_handshake_certs_check_both().

or_handshake_certs_free_()

void or_handshake_certs_free_

(

or_handshake_certs_t *

certs

)

Release all storage held in certs

Definition at line 478 of file torcert.c.

or_handshake_certs_new()

or_handshake_certs_t* or_handshake_certs_new

(

void

)

Construct and return a new empty or_handshake_certs object

Definition at line 471 of file torcert.c.

rsa_ed25519_crosscert_check()

int rsa_ed25519_crosscert_check	(	const uint8_t *	crosscert,
		const size_t	crosscert_len,
		const crypto_pk_t *	rsa_id_key,
		const ed25519_public_key_t *	master_key,
		const time_t	reject_if_expired_before
	)

Check whether the crosscert_len byte certificate in crosscert is in fact a correct cross-certification of master_key using the RSA key rsa_id_key.

Also reject the certificate if it expired before reject_if_expired_before.

Return 0 on success, negative on failure.

Definition at line 395 of file torcert.c.

tor_cert_checksig()

int tor_cert_checksig	(	tor_cert_t *	cert,
		const ed25519_public_key_t *	pubkey,
		time_t	now
	)

Validates the signature on cert with pubkey relative to the current time now. (If now is 0, do not check the expiration time.) Return 0 on success, -1 on failure. Sets flags in cert as appropriate.

Definition at line 244 of file torcert.c.

tor_cert_create_ed25519()

tor_cert_t* tor_cert_create_ed25519	(	const ed25519_keypair_t *	signing_key,
		uint8_t	cert_type,
		const ed25519_public_key_t *	signed_key,
		time_t	now,
		time_t	lifetime,
		uint32_t	flags
	)

Create and return a new new certificate of type cert_type to authenticate signed_key using the key signing_key. The certificate should remain valid for at least lifetime seconds after now.

If CERT_FLAG_INCLUDE_SIGNING_KEY is set in flags, embed the public part of signing_key in the certificate.

Definition at line 131 of file torcert.c.

Referenced by make_ntor_onion_key_crosscert(), and setup_desc_intro_point().

tor_cert_create_raw()

tor_cert_t* tor_cert_create_raw	(	const ed25519_keypair_t *	signing_key,
		uint8_t	cert_type,
		uint8_t	signed_key_type,
		const uint8_t	signed_key_info[32],
		time_t	now,
		time_t	lifetime,
		uint32_t	flags
	)

As tor_cert_create(), but accept an arbitrary signed_key_type as the subject key – not just an ed25519 key.

Definition at line 44 of file torcert.c.

Referenced by tor_cert_create_ed25519().

tor_cert_describe_signature_status()

const char* tor_cert_describe_signature_status

(

const tor_cert_t *

cert

)

Return a string describing the status of the signature on cert

Will always be "unchecked" unless tor_cert_checksig has been called.

Definition at line 279 of file torcert.c.

tor_cert_dup()

tor_cert_t* tor_cert_dup

(

const tor_cert_t *

cert

)

Return a new copy of cert

Definition at line 294 of file torcert.c.

tor_cert_eq()

int tor_cert_eq	(	const tor_cert_t *	cert1,
		const tor_cert_t *	cert2
	)

Return true iff cert1 and cert2 are the same cert.

Definition at line 304 of file torcert.c.

Referenced by tor_cert_opt_eq().

tor_cert_free_()

void tor_cert_free_

(

tor_cert_t *

cert

)

Release all storage held for cert.

Definition at line 144 of file torcert.c.

tor_cert_get_checkable_sig()

int tor_cert_get_checkable_sig	(	ed25519_checkable_t *	checkable_out,
		const tor_cert_t *	cert,
		const ed25519_public_key_t *	pubkey,
		time_t *	expiration_out
	)

Fill in checkable_out with the information needed to check the signature on cert with pubkey.

On success, if expiration_out is provided, and it is some time after the expiration time of this certificate, set it to the expiration time of this certificate.

Definition at line 211 of file torcert.c.

tor_cert_opt_eq()

int tor_cert_opt_eq	(	const tor_cert_t *	cert1,
		const tor_cert_t *	cert2
	)

Return true iff cert1 and cert2 are the same cert, or if they are both NULL.

Definition at line 315 of file torcert.c.

Referenced by routerinfo_incompatible_with_extrainfo().

tor_cert_parse()

tor_cert_t* tor_cert_parse	(	const uint8_t *	encoded,
		const size_t	len
	)

Parse a certificate encoded with len bytes in encoded.

Definition at line 159 of file torcert.c.

Referenced by cert_parse_and_validate().

tor_make_rsa_ed25519_crosscert()

ssize_t tor_make_rsa_ed25519_crosscert	(	const ed25519_public_key_t *	ed_key,
		const crypto_pk_t *	rsa_key,
		time_t	expires,
		uint8_t **	cert
	)

Create new cross-certification object to certify ed_key as the master ed25519 identity key for the RSA identity key rsa_key. Allocates and stores the encoded certificate in *cert, and returns the number of bytes stored. Returns negative on error.

Definition at line 331 of file torcert.c.