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prop224: Implement subcredential creation

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Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
David Goulet 2017-05-11 10:16:28 -04:00 committed by Nick Mathewson
parent f53b72baf7
commit c4ba4d4cc8
2 changed files with 47 additions and 0 deletions
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37
src/or/hs_common.c
View File

@ -500,6 +500,43 @@ hs_parse_address_impl(const char *address, ed25519_public_key_t *key_out,
tor_assert(offset == HS_SERVICE_ADDR_LEN);
}
/* Using the given identity public key and a blinded public key, compute the
* subcredential and put it in subcred_out. This can't fail. */
void
hs_get_subcredential(const ed25519_public_key_t *identity_pk,
const ed25519_public_key_t *blinded_pk,
uint8_t *subcred_out)
{
uint8_t credential[DIGEST256_LEN];
crypto_digest_t *digest;
tor_assert(identity_pk);
tor_assert(blinded_pk);
tor_assert(subcred_out);
/* First, build the credential. Construction is as follow:
* credential = H("credential" | public-identity-key) */
digest = crypto_digest256_new(DIGEST_SHA3_256);
crypto_digest_add_bytes(digest, HS_CREDENTIAL_PREFIX,
HS_CREDENTIAL_PREFIX_LEN);
crypto_digest_add_bytes(digest, (const char *) identity_pk->pubkey,
ED25519_PUBKEY_LEN);
crypto_digest_get_digest(digest, (char *) credential, DIGEST256_LEN);
crypto_digest_free(digest);
/* Now, compute the subcredential. Construction is as follow:
* subcredential = H("subcredential" | credential | blinded-public-key). */
digest = crypto_digest256_new(DIGEST_SHA3_256);
crypto_digest_add_bytes(digest, HS_SUBCREDENTIAL_PREFIX,
HS_SUBCREDENTIAL_PREFIX_LEN);
crypto_digest_add_bytes(digest, (const char *) credential,
sizeof(credential));
crypto_digest_add_bytes(digest, (const char *) blinded_pk->pubkey,
ED25519_PUBKEY_LEN);
crypto_digest_get_digest(digest, (char *) subcred_out, DIGEST256_LEN);
crypto_digest_free(digest);
}
/* Using a base32 representation of a service address, parse its content into
* the key_out, checksum_out and version_out. Any out variable can be NULL in
* case the caller would want only one field. checksum_out MUST at least be 2

10
src/or/hs_common.h
View File

@ -95,6 +95,12 @@
#define HS_KEYBLIND_NONCE_LEN \
(HS_KEYBLIND_NONCE_PREFIX_LEN + sizeof(uint64_t) + sizeof(uint64_t))
/* Credential and subcredential prefix value. */
#define HS_CREDENTIAL_PREFIX "credential"
#define HS_CREDENTIAL_PREFIX_LEN (sizeof(HS_CREDENTIAL_PREFIX) - 1)
#define HS_SUBCREDENTIAL_PREFIX "subcredential"
#define HS_SUBCREDENTIAL_PREFIX_LEN (sizeof(HS_SUBCREDENTIAL_PREFIX) - 1)
/* Type of authentication key used by an introduction point. */
typedef enum {
HS_AUTH_KEY_TYPE_LEGACY = 1,
@ -139,6 +145,10 @@ const char *rend_data_get_desc_id(const rend_data_t *rend_data,
const uint8_t *rend_data_get_pk_digest(const rend_data_t *rend_data,
size_t *len_out);
void hs_get_subcredential(const ed25519_public_key_t *identity_pk,
const ed25519_public_key_t *blinded_pk,
uint8_t *subcred_out);
uint64_t hs_get_time_period_num(time_t now);
uint64_t hs_get_next_time_period_num(time_t now);