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ca6ceec112
This commit adds the commit(s) line in the vote as well as the SR values. It also has the mechanism to add the majority SRVs in the consensus. Signed-off-by: George Kadianakis <desnacked@riseup.net> Signed-off-by: David Goulet <dgoulet@torproject.org>
134 lines
4.6 KiB
C
134 lines
4.6 KiB
C
/* Copyright (c) 2016, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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#ifndef TOR_SHARED_RANDOM_H
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#define TOR_SHARED_RANDOM_H
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/*
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* This file contains ABI/API of the shared random protocol defined in
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* proposal #250. Every public functions and data structure are namespaced
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* with "sr_" which stands for shared random.
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*/
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#include "or.h"
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/* Protocol version */
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#define SR_PROTO_VERSION 1
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/* Default digest algorithm. */
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#define SR_DIGEST_ALG DIGEST_SHA3_256
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/* Invariant token in the SRV calculation. */
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#define SR_SRV_TOKEN "shared-random"
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/* Don't count the NUL terminated byte even though the TOKEN has it. */
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#define SR_SRV_TOKEN_LEN (sizeof(SR_SRV_TOKEN) - 1)
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/* Length of the random number (in bytes). */
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#define SR_RANDOM_NUMBER_LEN 32
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/* Size of a decoded commit value in a vote or state. It's a hash and a
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* timestamp. It adds up to 40 bytes. */
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#define SR_COMMIT_LEN (sizeof(uint64_t) + DIGEST256_LEN)
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/* Size of a decoded reveal value from a vote or state. It's a 64 bit
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* timestamp and the hashed random number. This adds up to 40 bytes. */
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#define SR_REVEAL_LEN (sizeof(uint64_t) + DIGEST256_LEN)
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/* Size of SRV message length. The construction is has follow:
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* "shared-random" | INT_8(reveal_num) | INT_8(version) | PREV_SRV */
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#define SR_SRV_MSG_LEN \
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(SR_SRV_TOKEN_LEN + 1 + 1 + DIGEST256_LEN)
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/* Length of base64 encoded commit NOT including the NULL terminated byte.
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* Formula is taken from base64_encode_size. */
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#define SR_COMMIT_BASE64_LEN \
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(((SR_COMMIT_LEN - 1) / 3) * 4 + 4)
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/* Length of base64 encoded reveal NOT including the NULL terminated byte.
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* Formula is taken from base64_encode_size. This adds up to 56 bytes. */
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#define SR_REVEAL_BASE64_LEN \
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(((SR_REVEAL_LEN - 1) / 3) * 4 + 4)
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/* Length of base64 encoded shared random value. It's 32 bytes long so 44
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* bytes from the base64_encode_size formula. That includes the '='
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* character at the end. */
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#define SR_SRV_VALUE_BASE64_LEN \
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(((DIGEST256_LEN - 1) / 3) * 4 + 4)
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/* Protocol phase. */
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typedef enum {
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/* Commitment phase */
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SR_PHASE_COMMIT = 1,
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/* Reveal phase */
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SR_PHASE_REVEAL = 2,
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} sr_phase_t;
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/* A shared random value (SRV). */
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typedef struct sr_srv_t {
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/* The number of reveal values used to derive this SRV. */
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int num_reveals;
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/* The actual value. This is the stored result of SHA3-256. */
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uint8_t value[DIGEST256_LEN];
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} sr_srv_t;
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/* A commit (either ours or from another authority). */
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typedef struct sr_commit_t {
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/* Hashing algorithm used. */
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digest_algorithm_t alg;
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/* Commit owner info */
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/* The RSA identity fingerprint of the authority. */
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char rsa_identity_fpr[FINGERPRINT_LEN + 1];
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/* Commitment information */
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/* Timestamp of reveal. Correspond to TIMESTAMP. */
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time_t reveal_ts;
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/* H(REVEAL) as found in COMMIT message. */
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char hashed_reveal[DIGEST256_LEN];
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/* Base64 encoded COMMIT. We use this to put it in our vote. */
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char encoded_commit[SR_COMMIT_BASE64_LEN + 1];
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/* Reveal information */
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/* H(RN) which is what we used as the random value for this commit. We
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* don't use the raw bytes since those are sent on the network thus
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* avoiding possible information leaks of our PRNG. */
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uint8_t random_number[SR_RANDOM_NUMBER_LEN];
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/* Timestamp of commit. Correspond to TIMESTAMP. */
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time_t commit_ts;
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/* This is the whole reveal message. We use it during verification */
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char encoded_reveal[SR_REVEAL_BASE64_LEN + 1];
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} sr_commit_t;
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/* API */
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/* Public methods: */
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int sr_init(int save_to_disk);
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void sr_save_and_cleanup(void);
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sr_commit_t *sr_parse_commit(const smartlist_t *args);
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sr_srv_t *sr_parse_srv(const smartlist_t *args);
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char *sr_get_string_for_vote(void);
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char *sr_get_string_for_consensus(const smartlist_t *votes);
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void sr_commit_free(sr_commit_t *commit);
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void sr_srv_encode(char *dst, const sr_srv_t *srv);
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/* Private methods (only used by shared_random_state.c): */
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void sr_compute_srv(void);
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sr_commit_t *sr_generate_our_commit(time_t timestamp,
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const authority_cert_t *my_rsa_cert);
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#ifdef SHARED_RANDOM_PRIVATE
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/* Encode */
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STATIC int reveal_encode(const sr_commit_t *commit, char *dst, size_t len);
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STATIC int commit_encode(const sr_commit_t *commit, char *dst, size_t len);
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/* Decode. */
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STATIC int commit_decode(const char *encoded, sr_commit_t *commit);
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STATIC int reveal_decode(const char *encoded, sr_commit_t *commit);
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STATIC int commit_has_reveal_value(const sr_commit_t *commit);
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STATIC sr_srv_t *get_majority_srv_from_votes(const smartlist_t *votes,
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int current);
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#endif /* SHARED_RANDOM_PRIVATE */
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#endif /* TOR_SHARED_RANDOM_H */
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