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-rw-r--r--src/include/taler_json_lib.h25
-rw-r--r--src/json/json.c402
-rw-r--r--src/json/test_json.c2
3 files changed, 417 insertions, 12 deletions
diff --git a/src/include/taler_json_lib.h b/src/include/taler_json_lib.h
index 8550fd42a..cfab56fd6 100644
--- a/src/include/taler_json_lib.h
+++ b/src/include/taler_json_lib.h
@@ -158,6 +158,31 @@ int
TALER_JSON_contract_hash (const json_t *json,
struct GNUNET_HashCode *hc);
+
+/**
+ * Mark part of a contract object as 'forgettable'.
+ *
+ * @param[in,out] json some JSON object to modify
+ * @param field name of the field to mark as forgettable
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+int
+TALER_JSON_contract_mark_forgettable (json_t *json,
+ const char *field);
+
+
+/**
+ * Forget part of a contract object.
+ *
+ * @param[in,out] json some JSON object to modify
+ * @param field name of the field to forget
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+int
+TALER_JSON_contract_part_forget (json_t *json,
+ const char *field);
+
+
/**
* Extract the Taler error code from the given @a json object.
* Note that #TALER_EC_NONE is returned if no "code" is present.
diff --git a/src/json/json.c b/src/json/json.c
index a1a2c6fb4..4874f0c21 100644
--- a/src/json/json.c
+++ b/src/json/json.c
@@ -1,6 +1,6 @@
/*
This file is part of TALER
- Copyright (C) 2014, 2015, 2016 Taler Systems SA
+ Copyright (C) 2014, 2015, 2016, 2020 Taler Systems SA
TALER is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
@@ -25,7 +25,235 @@
/**
- * Hash a JSON object for binary signing.
+ * Dump the @a json to a string and hash it.
+ *
+ * @param json value to hash
+ * @param salt salt value to include when using HKDF,
+ * NULL to not use any salt and to use SHA512
+ * @param[out] hc where to store the hash
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
+ */
+static int
+dump_and_hash (const json_t *json,
+ const char *salt,
+ struct GNUNET_HashCode *hc)
+{
+ char *wire_enc;
+ size_t len;
+
+ if (NULL == (wire_enc = json_dumps (json,
+ JSON_COMPACT | JSON_SORT_KEYS)))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ len = strlen (wire_enc) + 1;
+ if (NULL == salt)
+ {
+ GNUNET_CRYPTO_hash (wire_enc,
+ len,
+ hc);
+ }
+ else
+ {
+ if (GNUNET_YES !=
+ GNUNET_CRYPTO_kdf (hc,
+ sizeof (*hc),
+ salt,
+ strlen (salt) + 1,
+ wire_enc,
+ len,
+ NULL,
+ 0))
+ {
+ free (wire_enc);
+ return GNUNET_SYSERR;
+ }
+ }
+ free (wire_enc);
+ return GNUNET_OK;
+}
+
+
+/**
+ * Replace "forgettable" parts of a JSON object with its salted hash.
+ *
+ * @param[in] in some JSON value
+ * @return NULL on error
+ */
+static json_t *
+forget (const json_t *in)
+{
+ if (json_is_array (in))
+ {
+ /* array is a JSON array */
+ size_t index;
+ json_t *value;
+ json_t *ret;
+
+ ret = json_array ();
+ if (NULL == ret)
+ {
+ GNUNET_break (0);
+ return NULL;
+ }
+ json_array_foreach (in, index, value) {
+ json_t *t;
+
+ t = forget (value);
+ if (NULL == t)
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ return NULL;
+ }
+ if (0 != json_array_append_new (ret, t))
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ return NULL;
+ }
+ }
+ return ret;
+ }
+ if (! json_is_object (in))
+ {
+ json_t *ret;
+ const char *key;
+ json_t *value;
+ json_t *fg;
+ json_t *rx;
+
+ fg = json_object_get (in,
+ "_forgettable");
+ rx = json_object_get (in,
+ "_forgotten");
+ if (NULL != rx)
+ rx = json_deep_copy (rx); /* should be shallow
+ by structure, but
+ deep copy is safer */
+ ret = json_object ();
+ if (NULL == ret)
+ {
+ GNUNET_break (0);
+ return NULL;
+ }
+ json_object_foreach ((json_t*) in, key, value) {
+ json_t *t;
+ json_t *salt;
+
+ if (0 == strcmp (key,
+ "_forgettable"))
+ continue; /* skip! */
+ if (rx == value)
+ continue; /* skip! */
+ t = forget (value);
+ if (NULL == t)
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ json_decref (rx);
+ return NULL;
+ }
+ if ( (NULL != fg) &&
+ (NULL != (salt = json_object_get (fg,
+ key))) )
+ {
+ /* 't' is to be forgotten! */
+ struct GNUNET_HashCode hc;
+
+ if (! json_is_string (salt))
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ json_decref (rx);
+ return NULL;
+ }
+ if (GNUNET_OK !=
+ dump_and_hash (t,
+ json_string_value (salt),
+ &hc))
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ json_decref (rx);
+ return NULL;
+ }
+ if (NULL == rx)
+ rx = json_object ();
+ if (NULL == rx)
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ json_decref (rx);
+ return NULL;
+ }
+ if (0 !=
+ json_object_set_new (rx,
+ key,
+ GNUNET_JSON_from_data_auto (&hc)))
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ json_decref (rx);
+ return NULL;
+ }
+ if (0 !=
+ json_object_set_new (ret,
+ key,
+ json_null ()))
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ json_decref (rx);
+ return NULL;
+ }
+
+ }
+ else
+ {
+ /* 't' to be used without 'forgetting' */
+ if (0 !=
+ json_object_set_new (ret,
+ key,
+ t))
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ json_decref (rx);
+ return NULL;
+ }
+ }
+ } /* json_object_foreach */
+ if (0 !=
+ json_object_set_new (ret,
+ "_forgotten",
+ rx))
+ {
+ GNUNET_break (0);
+ json_decref (ret);
+ return NULL;
+ }
+ return ret;
+ }
+ return json_incref ((json_t *) in);
+}
+
+
+/**
+ * Hash a JSON contract for binary signing.
+ *
+ * Contracts can contain "forgettable" parts. Those components of the JSON
+ * object are indicated in a "_forgettable" field containing key-value
+ * pairs. The keys are the names of other fields that are forgettable, and the
+ * values are salt values to be used in the HKDF when hashing the forgettable
+ * field. To compute the overall hash, the values of all "_forgettable" fields
+ * are replaced with 'null', and the "_forgettable" field itself is removed,
+ * and a special "_forgotten" field is added with a map of forgotten entries
+ * to the respective HKDF values (see also #6365).
+ *
+ * Forgetting parts is not only applied at the top-level entry of the
+ * contract, but recursively to all entries.
*
* See https://tools.ietf.org/html/draft-rundgren-json-canonicalization-scheme-15
* for fun JSON canonicalization problems. Callers must ensure that
@@ -41,20 +269,172 @@ int
TALER_JSON_contract_hash (const json_t *json,
struct GNUNET_HashCode *hc)
{
- char *wire_enc;
- size_t len;
+ int ret;
+ json_t *cjson;
- if (NULL == (wire_enc = json_dumps (json,
- JSON_COMPACT | JSON_SORT_KEYS)))
+ cjson = forget (json);
+ if (NULL == cjson)
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ ret = dump_and_hash (cjson,
+ NULL,
+ hc);
+ json_decref (cjson);
+ return ret;
+}
+
+
+/**
+ * Mark part of a contract object as 'forgettable'.
+ *
+ * @param[in,out] json some JSON object to modify
+ * @param field name of the field to mark as forgettable
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+int
+TALER_JSON_contract_mark_forgettable (json_t *json,
+ const char *field)
+{
+ json_t *fg;
+ struct GNUNET_ShortHashCode salt;
+
+ if (! json_is_object (json))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ if (NULL == json_object_get (json,
+ field))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ fg = json_object_get (json,
+ "_forgettable");
+ if (NULL == fg)
+ {
+ fg = json_object ();
+ if (0 !=
+ json_object_set_new (json,
+ "_forgettable",
+ fg))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ }
+
+ GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_NONCE,
+ &salt,
+ sizeof (salt));
+ if (0 !=
+ json_object_set_new (fg,
+ field,
+ GNUNET_JSON_from_data_auto (&salt)))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ return GNUNET_OK;
+}
+
+
+/**
+ * Forget part of a contract object.
+ *
+ * @param[in,out] json some JSON object to modify
+ * @param field name of the field to forget
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
+ */
+int
+TALER_JSON_contract_part_forget (json_t *json,
+ const char *field)
+{
+ const json_t *fg;
+ const json_t *part;
+ json_t *fp;
+ json_t *rx;
+ struct GNUNET_HashCode hc;
+ const char *salt;
+
+ if (! json_is_object (json))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ if (NULL == (part = json_object_get (json,
+ field)))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ fg = json_object_get (json,
+ "_forgettable");
+ if (NULL == fg)
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ salt = json_string_value (json_object_get (fg,
+ field));
+ if (NULL == salt)
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+
+ /* need to recursively forget to compute 'hc' */
+ fp = forget (part);
+ if (NULL == fp)
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ if (GNUNET_OK !=
+ dump_and_hash (fp,
+ salt,
+ &hc))
+ {
+ json_decref (fp);
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ json_decref (fp);
+
+ rx = json_object_get (json,
+ "_forgotten");
+ if (NULL == rx)
+ {
+ rx = json_object ();
+ if (0 !=
+ json_object_set_new (json,
+ "_forgotten",
+ rx))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ }
+ /* remember field as 'forgotten' */
+ if (0 !=
+ json_object_set_new (rx,
+ field,
+ GNUNET_JSON_from_data_auto (&hc)))
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+ /* finally, set 'forgotten' field to null */
+ if (0 !=
+ json_object_set_new (json,
+ field,
+ json_null ()))
{
GNUNET_break (0);
return GNUNET_SYSERR;
}
- len = strlen (wire_enc) + 1;
- GNUNET_CRYPTO_hash (wire_enc,
- len,
- hc);
- free (wire_enc);
return GNUNET_OK;
}
diff --git a/src/json/test_json.c b/src/json/test_json.c
index 732a3d774..2e7aba50a 100644
--- a/src/json/test_json.c
+++ b/src/json/test_json.c
@@ -1,6 +1,6 @@
/*
This file is part of TALER
- (C) 2015, 2016 Taler Systems SA
+ (C) 2015, 2016, 2020 Taler Systems SA
TALER is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
generated by cgit v1.2.3 (git 2.26.2) at 2024-10-30 04:38:20 +0000