-first cut at contract encryption and decryption
This commit is contained in:
Christian Grothoff
parent
ee4077ef80
commit
a227ee6d1b
@ -4287,6 +4287,9 @@ struct TALER_EXCHANGE_PurseDeposit
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* @param purse_expiration when will the unmerged purse expire
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* @param num_deposits length of the @a deposits array
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* @param deposits array of deposits to make into the purse
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* @param upload_contract true to upload the contract; must
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* be FALSE for repeated calls to this API for the
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* same purse (i.e. when adding more deposits).
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* @param cb function to call with the exchange's result
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* @param cb_cls closure for @a cb
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* @return the request handle; NULL upon error
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@ -4301,6 +4304,7 @@ TALER_EXCHANGE_purse_create_with_deposit (
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struct GNUNET_TIME_Timestamp purse_expiration,
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unsigned int num_deposits,
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const struct TALER_EXCHANGE_PurseDeposit *deposits,
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bool upload_contract,
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TALER_EXCHANGE_PurseCreateDepositCallback cb,
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void *cb_cls);
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@ -202,6 +202,7 @@ TALER_EXCHANGE_purse_create_with_deposit (
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struct GNUNET_TIME_Timestamp purse_expiration,
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unsigned int num_deposits,
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const struct TALER_EXCHANGE_PurseDeposit *deposits,
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bool upload_contract,
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TALER_EXCHANGE_PurseCreateDepositCallback cb,
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void *cb_cls)
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{
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@ -335,23 +336,25 @@ TALER_EXCHANGE_purse_create_with_deposit (
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}
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GNUNET_free (url);
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{
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void *econtract;
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size_t econtract_size;
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void *econtract = NULL;
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size_t econtract_size = 0;
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TALER_CRYPTO_contract_encrypt_for_merge (&purse_pub,
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contract_priv,
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merge_priv,
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contract_terms,
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&econtract,
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&econtract_size);
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if (upload_contract)
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TALER_CRYPTO_contract_encrypt_for_merge (&purse_pub,
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contract_priv,
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merge_priv,
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contract_terms,
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&econtract,
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&econtract_size);
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create_obj = GNUNET_JSON_PACK (
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TALER_JSON_pack_amount ("amount",
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&purse_value_after_fees),
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GNUNET_JSON_pack_uint64 ("min_age",
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min_age),
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GNUNET_JSON_pack_data_varsize ("econtract",
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econtract,
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econtract_size),
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GNUNET_JSON_pack_allow_null (
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GNUNET_JSON_pack_data_varsize ("econtract",
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econtract,
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econtract_size)),
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GNUNET_JSON_pack_data_auto ("contract_pub",
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&contract_pub),
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GNUNET_JSON_pack_data_auto ("merge_pub",
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@ -105,8 +105,11 @@ libtalerutil_la_SOURCES = \
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libtalerutil_la_LIBADD = \
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-lgnunetutil \
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-lsodium \
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-ljansson \
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$(LIBGCRYPT_LIBS) \
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-lmicrohttpd $(XLIB) \
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-lz \
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-lm
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libtalerutil_la_LDFLAGS = \
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@ -20,6 +20,191 @@
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*/
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#include "platform.h"
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#include "taler_util.h"
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#include <zlib.h>
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#include "taler_exchange_service.h"
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/**
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* Nonce used for encryption, 24 bytes.
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*/
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struct NonceP
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{
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uint8_t nonce[crypto_secretbox_NONCEBYTES];
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};
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/**
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* Specifies a key used for symmetric encryption, 32 bytes.
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*/
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struct SymKeyP
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{
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uint32_t key[8];
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};
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/**
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* Compute @a key.
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*
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* @param key_material key for calculation
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* @param key_m_len length of key
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* @param nonce nonce for calculation
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* @param salt salt value for calculation
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* @param[out] key where to write the en-/description key
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*/
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static void
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derive_key (const void *key_material,
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size_t key_m_len,
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const struct NonceP *nonce,
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const char *salt,
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struct SymKeyP *key)
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{
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GNUNET_assert (GNUNET_YES ==
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GNUNET_CRYPTO_kdf (key,
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sizeof (*key),
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/* salt / XTS */
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nonce,
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sizeof (*nonce),
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/* ikm */
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key_material,
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key_m_len,
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/* info chunks */
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/* The "salt" passed here is actually not something random,
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but a protocol-specific identifier string. Thus
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we pass it as a context info to the HKDF */
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salt,
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strlen (salt),
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NULL,
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0));
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}
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/**
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* Encryption of data.
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*
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* @param nonce value to use for the nonce
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* @param key key which is used to derive a key/iv pair from
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* @param key_len length of key
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* @param data data to encrypt
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* @param data_size size of the data
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* @param salt salt value which is used for key derivation
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* @param[out] res ciphertext output
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* @param[out] res_size size of the ciphertext
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*/
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static void
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encrypt (const struct NonceP *nonce,
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const void *key,
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size_t key_len,
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const void *data,
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size_t data_size,
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const char *salt,
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void **res,
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size_t *res_size)
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{
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size_t ciphertext_size;
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struct SymKeyP skey;
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derive_key (key,
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key_len,
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nonce,
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salt,
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&skey);
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ciphertext_size = crypto_secretbox_NONCEBYTES
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+ crypto_secretbox_MACBYTES + data_size;
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*res_size = ciphertext_size;
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*res = GNUNET_malloc (ciphertext_size);
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memcpy (*res, nonce, crypto_secretbox_NONCEBYTES);
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GNUNET_assert (0 ==
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crypto_secretbox_easy (*res + crypto_secretbox_NONCEBYTES,
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data,
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data_size,
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(void *) nonce,
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(void *) &skey));
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}
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/**
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* Decryption of data like encrypted recovery document etc.
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*
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* @param key key which is used to derive a key/iv pair from
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* @param key_len length of key
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* @param data data to decrypt
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* @param data_size size of the data
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* @param salt salt value which is used for key derivation
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* @param[out] res plaintext output
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* @param[out] res_size size of the plaintext
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* @return #GNUNET_OK on success
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*/
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static enum GNUNET_GenericReturnValue
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decrypt (const void *key,
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size_t key_len,
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const void *data,
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size_t data_size,
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const char *salt,
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void **res,
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size_t *res_size)
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{
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const struct NonceP *nonce;
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struct SymKeyP skey;
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size_t plaintext_size;
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if (data_size < crypto_secretbox_NONCEBYTES + crypto_secretbox_MACBYTES)
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{
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GNUNET_break (0);
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return GNUNET_SYSERR;
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}
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nonce = data;
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derive_key (key,
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key_len,
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nonce,
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salt,
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&skey);
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plaintext_size = data_size - (crypto_secretbox_NONCEBYTES
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+ crypto_secretbox_MACBYTES);
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*res = GNUNET_malloc (plaintext_size);
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*res_size = plaintext_size;
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if (0 != crypto_secretbox_open_easy (*res,
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data + crypto_secretbox_NONCEBYTES,
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data_size - crypto_secretbox_NONCEBYTES,
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(void *) nonce,
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(void *) &skey))
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{
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GNUNET_break (0);
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GNUNET_free (*res);
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return GNUNET_SYSERR;
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}
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return GNUNET_OK;
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}
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/**
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* Header for encrypted contracts.
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*/
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struct ContractHeader
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{
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/**
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* Type of the contract, in NBO.
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*/
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uint32_t ctype;
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/**
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* Length of the encrypted contract, in NBO.
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*/
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uint32_t clen;
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/**
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* Included key material, depending on @e ctype.
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*/
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union
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{
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struct TALER_PurseMergePrivateKeyP merge_priv;
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} keys;
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};
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/**
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* Salt we use when encrypting contracts for merge.
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*/
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#define MERGE_SALT "p2p-merge-contract"
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void
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@ -29,9 +214,52 @@ TALER_CRYPTO_contract_encrypt_for_merge (
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const struct TALER_PurseMergePrivateKeyP *merge_priv,
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const json_t *contract_terms,
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void **econtract,
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size_t *econtract_size)
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{
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struct GNUNET_HashCode key;
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char *cstr;
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size_t clen;
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void *xbuf;
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struct ContractHeader *hdr;
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struct NonceP nonce;
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uLongf cbuf_size;
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int ret;
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GNUNET_assert (GNUNET_OK ==
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GNUNET_CRYPTO_ecdh_eddsa (&contract_priv->ecdhe_priv,
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&purse_pub->eddsa_pub,
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&key));
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cstr = json_dumps (contract_terms,
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JSON_COMPACT | JSON_SORT_KEYS);
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clen = strlen (cstr);
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cbuf_size = compressBound (clen);
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xbuf = GNUNET_malloc (cbuf_size);
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ret = compress (xbuf,
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&cbuf_size,
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(const Bytef *) cstr,
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clen);
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GNUNET_assert (Z_OK == ret);
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free (cstr);
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hdr = GNUNET_malloc (sizeof (*hdr) + cbuf_size);
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hdr->ctype = htonl (TALER_EXCHANGE_CONTRACT_PAYMENT_OFFER);
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hdr->clen = htonl ((uint32_t) clen);
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hdr->keys.merge_priv = *merge_priv;
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memcpy (&hdr[1],
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xbuf,
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cbuf_size);
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GNUNET_free (xbuf);
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GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_NONCE,
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&nonce,
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sizeof (nonce));
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encrypt (&nonce,
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&key,
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sizeof (key),
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hdr,
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sizeof (*hdr) + cbuf_size,
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MERGE_SALT,
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econtract,
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econtract_size);
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GNUNET_free (hdr);
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}
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@ -43,5 +271,73 @@ TALER_CRYPTO_contract_decrypt_for_merge (
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size_t econtract_size,
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struct TALER_PurseMergePrivateKeyP *merge_priv)
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{
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return NULL;
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struct GNUNET_HashCode key;
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void *xhdr;
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size_t hdr_size;
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const struct ContractHeader *hdr;
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char *cstr;
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uLongf clen;
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json_error_t json_error;
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json_t *ret;
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if (GNUNET_OK !=
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GNUNET_CRYPTO_ecdh_eddsa (&contract_priv->ecdhe_priv,
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&purse_pub->eddsa_pub,
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&key))
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{
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GNUNET_break (0);
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return NULL;
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}
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if (GNUNET_OK !=
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decrypt (&key,
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sizeof (key),
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econtract,
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econtract_size,
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MERGE_SALT,
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&xhdr,
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&hdr_size))
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{
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GNUNET_break_op (0);
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return NULL;
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}
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if (hdr_size < sizeof (*hdr))
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{
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GNUNET_break_op (0);
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GNUNET_free (xhdr);
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return NULL;
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}
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hdr = xhdr;
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clen = ntohl (hdr->clen);
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if (clen >= GNUNET_MAX_MALLOC_CHECKED)
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{
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GNUNET_break_op (0);
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GNUNET_free (xhdr);
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return NULL;
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}
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cstr = GNUNET_malloc (clen + 1);
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if (Z_OK !=
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uncompress ((Bytef *) cstr,
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&clen,
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(const Bytef *) &hdr[1],
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hdr_size - sizeof (*hdr)))
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{
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GNUNET_break_op (0);
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GNUNET_free (cstr);
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GNUNET_free (xhdr);
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return NULL;
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}
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*merge_priv = hdr->keys.merge_priv;
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GNUNET_free (xhdr);
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ret = json_loadb ((char *) cstr,
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clen,
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JSON_DECODE_ANY,
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&json_error);
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if (NULL == ret)
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{
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GNUNET_break_op (0);
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GNUNET_free (cstr);
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return NULL;
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}
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GNUNET_free (cstr);
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return ret;
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}
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