wallet: allow adjusting number of rounds for the key derivation function

1 files changed, 8 insertions, 4 deletions

diff --git a/src/crypto/chacha.h b/src/crypto/chacha.h
index 2b3ed8043..1dc270faf 100644
--- a/src/crypto/chacha.h
+++ b/src/crypto/chacha.h
@@ -69,22 +69,26 @@ namespace crypto {
     chacha20(data, length, key.data(), reinterpret_cast<const uint8_t*>(&iv), cipher);
   }
 
-  inline void generate_chacha_key(const void *data, size_t size, chacha_key& key) {
+  inline void generate_chacha_key(const void *data, size_t size, chacha_key& key, uint64_t kdf_rounds) {
     static_assert(sizeof(chacha_key) <= sizeof(hash), "Size of hash must be at least that of chacha_key");
     tools::scrubbed_arr<char, HASH_SIZE> pwd_hash;
     crypto::cn_slow_hash(data, size, pwd_hash.data(), 0/*variant*/, 0/*prehashed*/);
+    for (uint64_t n = 1; n < kdf_rounds; ++n)
+      crypto::cn_slow_hash(pwd_hash.data(), pwd_hash.size(), pwd_hash.data(), 0/*variant*/, 0/*prehashed*/);
     memcpy(&unwrap(key), pwd_hash.data(), sizeof(key));
   }
 
-  inline void generate_chacha_key_prehashed(const void *data, size_t size, chacha_key& key) {
+  inline void generate_chacha_key_prehashed(const void *data, size_t size, chacha_key& key, uint64_t kdf_rounds) {
     static_assert(sizeof(chacha_key) <= sizeof(hash), "Size of hash must be at least that of chacha_key");
     tools::scrubbed_arr<char, HASH_SIZE> pwd_hash;
     crypto::cn_slow_hash(data, size, pwd_hash.data(), 0/*variant*/, 1/*prehashed*/);
+    for (uint64_t n = 1; n < kdf_rounds; ++n)
+      crypto::cn_slow_hash(pwd_hash.data(), pwd_hash.size(), pwd_hash.data(), 0/*variant*/, 0/*prehashed*/);
     memcpy(&unwrap(key), pwd_hash.data(), sizeof(key));
   }
 
-  inline void generate_chacha_key(std::string password, chacha_key& key) {
-    return generate_chacha_key(password.data(), password.size(), key);
+  inline void generate_chacha_key(std::string password, chacha_key& key, uint64_t kdf_rounds) {
+    return generate_chacha_key(password.data(), password.size(), key, kdf_rounds);
   }
 }