From c33c2e7e95d3f24a15e9fa3992ee7aa4be22fe5d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adrien=20B=C3=A9raud?= <adrien.beraud@savoirfairelinux.com>
Date: Tue, 6 Sep 2016 12:06:21 -0400
Subject: [PATCH] crypto: add key, hash length parameters
---
include/opendht/crypto.h | 11 ++++++++---
src/crypto.cpp | 33 ++++++++++++++++++++++-----------
2 files changed, 30 insertions(+), 14 deletions(-)
diff --git a/include/opendht/crypto.h b/include/opendht/crypto.h
index eaa28dd5..897abd25 100644
--- a/include/opendht/crypto.h
+++ b/include/opendht/crypto.h
@@ -329,9 +329,14 @@ Identity generateIdentity(const std::string& name = "dhtnode", Identity ca = {},
/**
- * SHA512
+ * Performs SHA512, SHA256 or SHA1, depending on hash_length.
+ * Attempts to choose an hash function with
+ * output size of at least hash_length bytes, Current implementation
+ * will use SHA1 for hash_length up to 20 bytes,
+ * will use SHA256 for hash_length up to 32 bytes,
+ * will use SHA512 for hash_length of 33 bytes and more.
*/
-Blob hash(const Blob& data);
+Blob hash(const Blob& data, size_t hash_length = 512/8);
/**
* Generates an encryption key from a text password,
@@ -340,7 +345,7 @@ Blob hash(const Blob& data);
* that can be transmitted in clear, and will be generated if
* not provided (32 bytes).
*/
-Blob stretchKey(const std::string& password, Blob& salt);
+Blob stretchKey(const std::string& password, Blob& salt, size_t key_length = 512/8);
/**
* AES-GCM encryption. Key must be 128, 192 or 256 bits long (16, 24 or 32 bytes).
diff --git a/src/crypto.cpp b/src/crypto.cpp
index cca5de87..36d006b5 100644
--- a/src/crypto.cpp
+++ b/src/crypto.cpp
@@ -83,6 +83,18 @@ namespace crypto {
static constexpr std::array<size_t, 3> AES_LENGTHS {{128/8, 192/8, 256/8}};
static constexpr size_t PASSWORD_SALT_LENGTH {16};
+constexpr gnutls_digest_algorithm_t gnutlsHashAlgo(size_t min_res) {
+ return (min_res > 256/8) ? GNUTLS_DIG_SHA512 : (
+ (min_res > 128/8) ? GNUTLS_DIG_SHA256 : (
+ GNUTLS_DIG_SHA1));
+}
+
+constexpr size_t gnutlsHashSize(int algo) {
+ return (algo == GNUTLS_DIG_SHA512) ? 512/8 : (
+ (algo == GNUTLS_DIG_SHA256) ? 256/8 : (
+ (algo == GNUTLS_DIG_SHA1) ? 160/8 : 0 ));
+}
+
size_t aesKeySize(size_t max)
{
size_t aes_key_len = 0;
@@ -108,7 +120,7 @@ bool aesKeySizeGood(size_t key_size)
Blob aesEncrypt(const Blob& data, const Blob& key)
{
if (not aesKeySizeGood(key.size()))
- throw DecryptError("Wrong key size");
+ throw DecryptError("Wrong key size: " + std::to_string(key.size()));
Blob ret(data.size() + GCM_IV_SIZE + GCM_DIGEST_SIZE);
{
@@ -128,8 +140,7 @@ Blob aesEncrypt(const Blob& data, const Blob& key)
Blob aesEncrypt(const Blob& data, const std::string& password)
{
Blob salt;
- Blob key = stretchKey(password, salt);
- key.resize(256 / 8);
+ Blob key = stretchKey(password, salt, 256 / 8);
Blob encrypted = aesEncrypt(data, key);
encrypted.insert(encrypted.begin(), salt.begin(), salt.end());
return encrypted;
@@ -175,13 +186,12 @@ Blob aesDecrypt(const Blob& data, const std::string& password)
if (data.size() <= PASSWORD_SALT_LENGTH)
throw DecryptError("Wrong data size");
Blob salt {data.begin(), data.begin()+PASSWORD_SALT_LENGTH};
- Blob key = stretchKey(password, salt);
- key.resize(256 / 8);
+ Blob key = stretchKey(password, salt, 256/8);
Blob encrypted {data.begin()+PASSWORD_SALT_LENGTH, data.end()};
return aesDecrypt(encrypted, key);
}
-Blob stretchKey(const std::string& password, Blob& salt)
+Blob stretchKey(const std::string& password, Blob& salt, size_t key_length)
{
if (salt.empty()) {
salt.resize(PASSWORD_SALT_LENGTH);
@@ -193,18 +203,19 @@ Blob stretchKey(const std::string& password, Blob& salt)
auto ret = argon2i_hash_raw(16, 64*1024, 1, password.data(), password.size(), salt.data(), salt.size(), res.data(), res.size());
if (ret != ARGON2_OK)
throw CryptoException("Can't compute argon2i !");
- return hash(res);
+ return hash(res, key_length);
}
-Blob hash(const Blob& data)
+Blob hash(const Blob& data, size_t hash_len)
{
+ auto algo = gnutlsHashAlgo(hash_len);
+ size_t res_size = gnutlsHashSize(algo);
Blob res;
- size_t res_size = 64;
res.resize(res_size);
const gnutls_datum_t gdat {(uint8_t*)data.data(), (unsigned)data.size()};
- if (gnutls_fingerprint(GNUTLS_DIG_SHA512, &gdat, res.data(), &res_size))
+ if (gnutls_fingerprint(algo, &gdat, res.data(), &res_size))
throw CryptoException("Can't compute hash !");
- res.resize(res_size);
+ res.resize(std::min(hash_len, res_size));
return res;
}
--
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