Add methods for generating new one time keys and for tracking which one time...

Add methods for generating new one time keys and for tracking which one time keys have been published

include/olm/account.hh

@@ -31,6 +31,7 @@ struct IdentityKeys {
 
 struct OneTimeKey {
     std::uint32_t id;
+    bool published;
     Curve25519KeyPair key;
 };
 
@@ -39,15 +40,17 @@ static std::size_t const MAX_ONE_TIME_KEYS = 100;
 
 
 struct Account {
+    Account();
     IdentityKeys identity_keys;
     List<OneTimeKey, MAX_ONE_TIME_KEYS> one_time_keys;
+    std::uint32_t next_one_time_key_id;
     ErrorCode last_error;
 
     /** Number of random bytes needed to create a new account */
     std::size_t new_account_random_length();
 
-    /** Create a new account. Returns NOT_ENOUGH_RANDOM if the number of random
-     * bytes is too small. */
+    /** Create a new account. Returns std::size_t(-1) on error. If the number of
+     * random bytes is too small then last_error will be NOT_ENOUGH_RANDOM */
     std::size_t new_account(
         uint8_t const * random, std::size_t random_length
     );
@@ -61,35 +64,30 @@ struct Account {
     );
 
     /** Output the identity keys for this account as JSON in the following
-     * format.
+     * format:
      *
-     *  14 {"algorithms":
-     *  30 ["m.olm.curve25519-aes-sha256"
-     *  15 ],"device_id":"
-     *   ? <device identifier>
-     *  22 ","keys":{"curve25519:
-     *   4 <base64 characters>
-     *   3 ":"
-     *  43 <base64 characters>
-     *  11 ","ed25519:
-     *   4 <base64 characters>
-     *   3 ":"
-     *  43 <base64 characters>
-     *  14 "},"user_id":"
-     *   ? <user identifier>
-     *  19 ","valid_after_ts":
-     *   ? <digits>
-     *  18 ,"valid_until_ts":
-     *   ? <digits>
-     *  16 ,"signatures":{"
-     *   ? <user identifier>
-     *   1 /
-     *   ? <device identifier>
-     *  12 ":{"ed25519:
-     *   4 <base64 characters>
-     *   3 ":"
-     *  86 <base64 characters>
-     *   4 "}}}
+     *    {"algorithms":
+     *    ["m.olm.curve25519-aes-sha256"
+     *    ]
+     *    ,"device_id":"<device identifier>"
+     *    ,"keys":
+     *    {"curve25519:<key id>":"<base64 characters>"
+     *    ,"ed25519:<key id>":"<base64 characters>"
+     *    }
+     *    ,"user_id":"<user identifier>"
+     *    ,"valid_after_ts":<digits>
+     *    ,"valid_until_ts":<digits>
+     *    ,"signatures":
+     *    {"<user identifier>/<device identifier>":
+     *    {"ed25519:<key id>":"<base64 characters>"
+     *    }
+     *    }
+     *    }
+     *
+     * The user_id and device_id must not contain 0x00-0x1F, '\"' or '\\'.
+     * The JSON up to but not including the "signatures" key will be signed
+     * using the account's ed25519 key. That signature is then included under
+     * the "signatures" key.
      *
      * Returns the size of the JSON written or std::size_t(-1) on error.
      * If the buffer is too small last_error will be OUTPUT_BUFFER_TOO_SMALL. */
@@ -104,7 +102,13 @@ struct Account {
     /** Number of bytes needed to output the one time keys for this account */
     std::size_t get_one_time_keys_json_length();
 
-    /*
+    /** Output the one time keys that haven't been published yet as JSON:
+     *
+     *  {"curve25519:<key id>":"<base64 characters>"
+     *  ,"curve25519:<key_id>":"<base64 characters>"
+     *  ...
+     *  }
+     *
      * Returns the size of the JSON written or std::size_t(-1) on error.
      * If the buffer is too small last_error will be OUTPUT_BUFFER_TOO_SMALL.
      */
@@ -112,6 +116,28 @@ struct Account {
         std::uint8_t * one_time_json, std::size_t one_time_json_length
     );
 
+    /** Mark the current list of one_time_keys as being published. They
+     * will no longer be returned by get_one_time_keys_json_length(). */
+    std::size_t mark_keys_as_published();
+
+    /** The largest number of one time keys this account can store. */
+    std::size_t max_number_of_one_time_keys();
+
+    /** Returns the number of random bytes needed to generate a given number
+     * of new one time keys. */
+    std::size_t generate_one_time_keys_random_length(
+        std::size_t number_of_keys
+    );
+
+    /** Generates a number of new one time keys. If the total number of keys
+     * stored by this account exceeds max_number_of_one_time_keys() then the
+     * old keys are discarded. Returns std::size_t(-1) on error. If the number
+     * of random bytes is too small then last_error will be NOT_ENOUGH_RANDOM */
+    std::size_t generate_one_time_keys(
+        std::size_t number_of_keys,
+        std::uint8_t const * random, std::size_t random_length
+    );
+
     /** Lookup a one time key with the given public key */
     OneTimeKey const * lookup_key(
         Curve25519PublicKey const & public_key

src/account.cpp

@@ -16,6 +16,11 @@
 #include "olm/base64.hh"
 #include "olm/pickle.hh"
 
+olm::Account::Account(
+) : next_one_time_key_id(0),
+    last_error(olm::ErrorCode::SUCCESS) {
+}
+
 
 olm::OneTimeKey const * olm::Account::lookup_key(
     olm::Curve25519PublicKey const & public_key
@@ -54,19 +59,12 @@ std::size_t olm::Account::new_account(
         return std::size_t(-1);
     }
 
-    unsigned id = 0;
-
     olm::ed25519_generate_key(random, identity_keys.ed25519_key);
     random += 32;
     olm::curve25519_generate_key(random, identity_keys.curve25519_key);
     random += 32;
 
-    for (unsigned i = 0; i < 10; ++i) {
-        OneTimeKey & key = *one_time_keys.insert(one_time_keys.end());
-        key.id = ++id;
-        olm::curve25519_generate_key(random, key.key);
-        random += 32;
-    }
+    generate_one_time_keys(10, random, random_length - 64);
 
     return 0;
 }
@@ -236,6 +234,9 @@ std::size_t olm::Account::get_one_time_keys_json_length(
 ) {
     std::size_t length = 0;
     for (auto const & key : one_time_keys) {
+        if (key.published) {
+            continue;
+        }
         length += 2; /* {" */
         length += sizeof(ONE_TIME_KEY_JSON_ALG) - 1;
         length += 1; /* : */
@@ -262,6 +263,9 @@ std::size_t olm::Account::get_one_time_keys_json(
     }
     std::uint8_t sep = '{';
     for (auto const & key : one_time_keys) {
+        if (key.published) {
+            continue;
+        }
         *(pos++) = sep;
         *(pos++) = '\"';
         pos = write_string(pos, ONE_TIME_KEY_JSON_ALG);
@@ -284,6 +288,48 @@ std::size_t olm::Account::get_one_time_keys_json(
 }
 
 
+std::size_t olm::Account::mark_keys_as_published(
+) {
+    std::size_t count = 0;
+    for (auto & key : one_time_keys) {
+        if (!key.published) {
+            key.published = true;
+            count++;
+        }
+    }
+    return count;
+}
+
+
+std::size_t olm::Account::max_number_of_one_time_keys(
+) {
+    return olm::MAX_ONE_TIME_KEYS;
+}
+
+std::size_t olm::Account::generate_one_time_keys_random_length(
+    std::size_t number_of_keys
+) {
+    return 32 * number_of_keys;
+}
+
+std::size_t olm::Account::generate_one_time_keys(
+    std::size_t number_of_keys,
+    std::uint8_t const * random, std::size_t random_length
+) {
+    if (random_length < generate_one_time_keys_random_length(number_of_keys)) {
+        last_error = olm::ErrorCode::NOT_ENOUGH_RANDOM;
+        return std::size_t(-1);
+    }
+    for (unsigned i = 0; i < number_of_keys; ++i) {
+        OneTimeKey & key = *one_time_keys.insert(one_time_keys.begin());
+        key.id = ++next_one_time_key_id;
+        key.published = false;
+        olm::curve25519_generate_key(random, key.key);
+        random += 32;
+    }
+    return number_of_keys;
+}
+
 namespace olm {
 
 static std::size_t pickle_length(
@@ -319,7 +365,11 @@ static std::uint8_t const * unpickle(
 static std::size_t pickle_length(
     olm::OneTimeKey const & value
 ) {
-    return olm::pickle_length(value.id) + olm::pickle_length(value.key);
+    std::size_t length = 0;
+    length += olm::pickle_length(value.id);
+    length += olm::pickle_length(value.published);
+    length += olm::pickle_length(value.key);
+    return length;
 }
 
 
@@ -328,6 +378,7 @@ static std::uint8_t * pickle(
     olm::OneTimeKey const & value
 ) {
     pos = olm::pickle(pos, value.id);
+    pos = olm::pickle(pos, value.published);
     pos = olm::pickle(pos, value.key);
     return pos;
 }
@@ -338,6 +389,7 @@ static std::uint8_t const * unpickle(
     olm::OneTimeKey & value
 ) {
     pos = olm::unpickle(pos, end, value.id);
+    pos = olm::unpickle(pos, end, value.published);
     pos = olm::unpickle(pos, end, value.key);
     return pos;
 }
@@ -351,6 +403,7 @@ std::size_t olm::pickle_length(
     std::size_t length = 0;
     length += olm::pickle_length(value.identity_keys);
     length += olm::pickle_length(value.one_time_keys);
+    length += olm::pickle_length(value.next_one_time_key_id);
     return length;
 }
 
@@ -361,6 +414,7 @@ std::uint8_t * olm::pickle(
 ) {
     pos = olm::pickle(pos, value.identity_keys);
     pos = olm::pickle(pos, value.one_time_keys);
+    pos = olm::pickle(pos, value.next_one_time_key_id);
     return pos;
 }
 
@@ -371,5 +425,6 @@ std::uint8_t const * olm::unpickle(
 ) {
     pos = olm::unpickle(pos, end, value.identity_keys);
     pos = olm::unpickle(pos, end, value.one_time_keys);
+    pos = olm::unpickle(pos, end, value.next_one_time_key_id);
     return pos;
 }