commit 163596d9c25d4836dde37675372271d8358ffc81 Author: George Kadianakis desnacked@riseup.net Date: Wed Feb 8 13:22:36 2017 +0200

prop224: Move some utility crypto funcs to the top of the file. --- src/or/hs_descriptor.c | 258 ++++++++++++++++++++++++------------------------- 1 file changed, 129 insertions(+), 129 deletions(-)

diff --git a/src/or/hs_descriptor.c b/src/or/hs_descriptor.c index 54788e6..7c43d60 100644 --- a/src/or/hs_descriptor.c +++ b/src/or/hs_descriptor.c @@ -195,6 +195,135 @@ desc_encrypted_data_free_contents(hs_desc_encrypted_data_t *desc) memwipe(desc, 0, sizeof(*desc)); }

+/* Using a key, salt and encrypted payload, build a MAC and put it in mac_out. + * We use SHA3-256 for the MAC computation. + * This function can't fail. */ +static void +build_mac(const uint8_t *mac_key, size_t mac_key_len, + const uint8_t *salt, size_t salt_len, + const uint8_t *encrypted, size_t encrypted_len, + uint8_t *mac_out, size_t mac_len) +{ + crypto_digest_t *digest; + + const uint64_t mac_len_netorder = tor_htonll(mac_key_len); + const uint64_t salt_len_netorder = tor_htonll(salt_len); + + tor_assert(mac_key); + tor_assert(salt); + tor_assert(encrypted); + tor_assert(mac_out); + + digest = crypto_digest256_new(DIGEST_SHA3_256); + /* As specified in section 2.5 of proposal 224, first add the mac key + * then add the salt first and then the encrypted section. */ + + crypto_digest_add_bytes(digest, (const char *) &mac_len_netorder, 8); + crypto_digest_add_bytes(digest, (const char *) mac_key, mac_key_len); + crypto_digest_add_bytes(digest, (const char *) &salt_len_netorder, 8); + crypto_digest_add_bytes(digest, (const char *) salt, salt_len); + crypto_digest_add_bytes(digest, (const char *) encrypted, encrypted_len); + crypto_digest_get_digest(digest, (char *) mac_out, mac_len); + crypto_digest_free(digest); +} + +/* Using a given decriptor object, build the secret input needed for the + * KDF and put it in the dst pointer which is an already allocated buffer + * of size dstlen. */ +static void +build_secret_input(const hs_descriptor_t *desc, uint8_t *dst, size_t dstlen) +{ + size_t offset = 0; + + tor_assert(desc); + tor_assert(dst); + tor_assert(HS_DESC_ENCRYPTED_SECRET_INPUT_LEN <= dstlen); + + /* XXX use the destination length as the memcpy length */ + /* Copy blinded public key. */ + memcpy(dst, desc->plaintext_data.blinded_pubkey.pubkey, + sizeof(desc->plaintext_data.blinded_pubkey.pubkey)); + offset += sizeof(desc->plaintext_data.blinded_pubkey.pubkey); + /* Copy subcredential. */ + memcpy(dst + offset, desc->subcredential, sizeof(desc->subcredential)); + offset += sizeof(desc->subcredential); + /* Copy revision counter value. */ + set_uint64(dst + offset, tor_ntohll(desc->plaintext_data.revision_counter)); + offset += sizeof(uint64_t); + tor_assert(HS_DESC_ENCRYPTED_SECRET_INPUT_LEN == offset); +} + +/* Do the KDF construction and put the resulting data in key_out which is of + * key_out_len length. It uses SHAKE-256 as specified in the spec. */ +static void +build_kdf_key(const hs_descriptor_t *desc, + const uint8_t *salt, size_t salt_len, + uint8_t *key_out, size_t key_out_len, + int is_superencrypted_layer) +{ + uint8_t secret_input[HS_DESC_ENCRYPTED_SECRET_INPUT_LEN]; + crypto_xof_t *xof; + + tor_assert(desc); + tor_assert(salt); + tor_assert(key_out); + + /* Build the secret input for the KDF computation. */ + build_secret_input(desc, secret_input, sizeof(secret_input)); + + xof = crypto_xof_new(); + /* Feed our KDF. [SHAKE it like a polaroid picture --Yawning]. */ + crypto_xof_add_bytes(xof, secret_input, sizeof(secret_input)); + crypto_xof_add_bytes(xof, salt, salt_len); + + /* Feed in the right string constant based on the desc layer */ + if (is_superencrypted_layer) { + crypto_xof_add_bytes(xof, (const uint8_t *) str_enc_const_superencryption, + strlen(str_enc_const_superencryption)); + } else { + crypto_xof_add_bytes(xof, (const uint8_t *) str_enc_const_encryption, + strlen(str_enc_const_encryption)); + } + + /* Eat from our KDF. */ + crypto_xof_squeeze_bytes(xof, key_out, key_out_len); + crypto_xof_free(xof); + memwipe(secret_input, 0, sizeof(secret_input)); +} + +/* Using the given descriptor and salt, run it through our KDF function and + * then extract a secret key in key_out, the IV in iv_out and MAC in mac_out. + * This function can't fail. */ +static void +build_secret_key_iv_mac(const hs_descriptor_t *desc, + const uint8_t *salt, size_t salt_len, + uint8_t *key_out, size_t key_len, + uint8_t *iv_out, size_t iv_len, + uint8_t *mac_out, size_t mac_len, + int is_superencrypted_layer) +{ + size_t offset = 0; + uint8_t kdf_key[HS_DESC_ENCRYPTED_KDF_OUTPUT_LEN]; + + tor_assert(desc); + tor_assert(salt); + tor_assert(key_out); + tor_assert(iv_out); + tor_assert(mac_out); + + build_kdf_key(desc, salt, salt_len, kdf_key, sizeof(kdf_key), + is_superencrypted_layer); + /* Copy the bytes we need for both the secret key and IV. */ + memcpy(key_out, kdf_key, key_len); + offset += key_len; + memcpy(iv_out, kdf_key + offset, iv_len); + offset += iv_len; + memcpy(mac_out, kdf_key + offset, mac_len); + /* Extra precaution to make sure we are not out of bound. */ + tor_assert((offset + mac_len) == sizeof(kdf_key)); + memwipe(kdf_key, 0, sizeof(kdf_key)); +} + /* === ENCODING === */

/* Encode the given link specifier objects into a newly allocated string. @@ -423,135 +552,6 @@ encode_intro_point(const ed25519_public_key_t *sig_key, return encoded_ip; }

-/* Using a given decriptor object, build the secret input needed for the - * KDF and put it in the dst pointer which is an already allocated buffer - * of size dstlen. */ -static void -build_secret_input(const hs_descriptor_t *desc, uint8_t *dst, size_t dstlen) -{ - size_t offset = 0; - - tor_assert(desc); - tor_assert(dst); - tor_assert(HS_DESC_ENCRYPTED_SECRET_INPUT_LEN <= dstlen); - - /* XXX use the destination length as the memcpy length */ - /* Copy blinded public key. */ - memcpy(dst, desc->plaintext_data.blinded_pubkey.pubkey, - sizeof(desc->plaintext_data.blinded_pubkey.pubkey)); - offset += sizeof(desc->plaintext_data.blinded_pubkey.pubkey); - /* Copy subcredential. */ - memcpy(dst + offset, desc->subcredential, sizeof(desc->subcredential)); - offset += sizeof(desc->subcredential); - /* Copy revision counter value. */ - set_uint64(dst + offset, tor_ntohll(desc->plaintext_data.revision_counter)); - offset += sizeof(uint64_t); - tor_assert(HS_DESC_ENCRYPTED_SECRET_INPUT_LEN == offset); -} - -/* Do the KDF construction and put the resulting data in key_out which is of - * key_out_len length. It uses SHAKE-256 as specified in the spec. */ -static void -build_kdf_key(const hs_descriptor_t *desc, - const uint8_t *salt, size_t salt_len, - uint8_t *key_out, size_t key_out_len, - int is_superencrypted_layer) -{ - uint8_t secret_input[HS_DESC_ENCRYPTED_SECRET_INPUT_LEN]; - crypto_xof_t *xof; - - tor_assert(desc); - tor_assert(salt); - tor_assert(key_out); - - /* Build the secret input for the KDF computation. */ - build_secret_input(desc, secret_input, sizeof(secret_input)); - - xof = crypto_xof_new(); - /* Feed our KDF. [SHAKE it like a polaroid picture --Yawning]. */ - crypto_xof_add_bytes(xof, secret_input, sizeof(secret_input)); - crypto_xof_add_bytes(xof, salt, salt_len); - - /* Feed in the right string constant based on the desc layer */ - if (is_superencrypted_layer) { - crypto_xof_add_bytes(xof, (const uint8_t *) str_enc_const_superencryption, - strlen(str_enc_const_superencryption)); - } else { - crypto_xof_add_bytes(xof, (const uint8_t *) str_enc_const_encryption, - strlen(str_enc_const_encryption)); - } - - /* Eat from our KDF. */ - crypto_xof_squeeze_bytes(xof, key_out, key_out_len); - crypto_xof_free(xof); - memwipe(secret_input, 0, sizeof(secret_input)); -} - -/* Using the given descriptor and salt, run it through our KDF function and - * then extract a secret key in key_out, the IV in iv_out and MAC in mac_out. - * This function can't fail. */ -static void -build_secret_key_iv_mac(const hs_descriptor_t *desc, - const uint8_t *salt, size_t salt_len, - uint8_t *key_out, size_t key_len, - uint8_t *iv_out, size_t iv_len, - uint8_t *mac_out, size_t mac_len, - int is_superencrypted_layer) -{ - size_t offset = 0; - uint8_t kdf_key[HS_DESC_ENCRYPTED_KDF_OUTPUT_LEN]; - - tor_assert(desc); - tor_assert(salt); - tor_assert(key_out); - tor_assert(iv_out); - tor_assert(mac_out); - - build_kdf_key(desc, salt, salt_len, kdf_key, sizeof(kdf_key), - is_superencrypted_layer); - /* Copy the bytes we need for both the secret key and IV. */ - memcpy(key_out, kdf_key, key_len); - offset += key_len; - memcpy(iv_out, kdf_key + offset, iv_len); - offset += iv_len; - memcpy(mac_out, kdf_key + offset, mac_len); - /* Extra precaution to make sure we are not out of bound. */ - tor_assert((offset + mac_len) == sizeof(kdf_key)); - memwipe(kdf_key, 0, sizeof(kdf_key)); -} - -/* Using a key, salt and encrypted payload, build a MAC and put it in mac_out. - * We use SHA3-256 for the MAC computation. - * This function can't fail. */ -static void -build_mac(const uint8_t *mac_key, size_t mac_key_len, - const uint8_t *salt, size_t salt_len, - const uint8_t *encrypted, size_t encrypted_len, - uint8_t *mac_out, size_t mac_len) -{ - crypto_digest_t *digest; - - const uint64_t mac_len_netorder = tor_htonll(mac_key_len); - const uint64_t salt_len_netorder = tor_htonll(salt_len); - - tor_assert(mac_key); - tor_assert(salt); - tor_assert(encrypted); - tor_assert(mac_out); - - digest = crypto_digest256_new(DIGEST_SHA3_256); - /* As specified in section 2.5 of proposal 224, first add the mac key - * then add the salt first and then the encrypted section. */ - - crypto_digest_add_bytes(digest, (const char *) &mac_len_netorder, 8); - crypto_digest_add_bytes(digest, (const char *) mac_key, mac_key_len); - crypto_digest_add_bytes(digest, (const char *) &salt_len_netorder, 8); - crypto_digest_add_bytes(digest, (const char *) salt, salt_len); - crypto_digest_add_bytes(digest, (const char *) encrypted, encrypted_len); - crypto_digest_get_digest(digest, (char *) mac_out, mac_len); - crypto_digest_free(digest); -} - /* Given a source length, return the new size including padding for the * plaintext encryption. */ static size_t