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Add challenge response to key before transformation, resolves #1060

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* Re-implement KDBX4 challenge-response key assembly with transform
seed instead of master seed
This commit is contained in:
Janek Bevendorff
2018-01-07 18:46:24 +01:00
committed by Jonathan White
parent a6ddc22fb8
commit df728083cc
5 changed files with 67 additions and 18 deletions
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54
src/keys/CompositeKey.cpp
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@@ -19,6 +19,7 @@
#include "CompositeKey.h"
#include <QFile>
#include <QtConcurrent>
#include <format/KeePass2.h>
#include "core/Global.h"
#include "crypto/CryptoHash.h"
@@ -73,7 +74,31 @@ CompositeKey& CompositeKey::operator=(const CompositeKey& key)
return *this;
}
/**
* Get raw key hash as bytes.
*
* The key hash does not contain contributions by challenge-response components for
* backwards compatibility with KeePassXC's pre-KDBX4 challenge-response
* implementation. To include challenge-response in the raw key,
* use \link CompositeKey::rawKey(const QByteArray*) instead.
*
* @return key hash
*/
QByteArray CompositeKey::rawKey() const
{
return rawKey(nullptr);
}
/**
* Get raw key hash as bytes.
*
* Challenge-response key components will use the provided <tt>transformSeed</tt>
* as a challenge to acquire their key contribution.
*
* @param transformSeed transform seed to challenge or nullptr to exclude challenge-response components
* @return key hash
*/
QByteArray CompositeKey::rawKey(const QByteArray* transformSeed) const
{
CryptoHash cryptoHash(CryptoHash::Sha256);
@@ -81,12 +106,38 @@ QByteArray CompositeKey::rawKey() const
cryptoHash.addData(key->rawKey());
}
if (transformSeed) {
QByteArray challengeResult;
challenge(*transformSeed, challengeResult);
cryptoHash.addData(challengeResult);
}
return cryptoHash.result();
}
/**
* Transform this composite key.
*
* If using AES-KDF as transform function, the transformed key will not include
* any challenge-response components. Only static key components will be hashed
* for backwards-compatibility with KeePassXC's KDBX3 implementation, which added
* challenge response key components after key transformation.
* KDBX4+ KDFs transform the whole key including challenge-response components.
*
* @param kdf key derivation function
* @param result transformed key hash
* @return true on success
*/
bool CompositeKey::transform(const Kdf& kdf, QByteArray& result) const
{
return kdf.transform(rawKey(), result);
if (kdf.uuid() == KeePass2::KDF_AES) {
// legacy KDBX3 AES-KDF, challenge response is added later to the hash
return kdf.transform(rawKey(), result);
}
QByteArray seed = kdf.seed();
Q_ASSERT(!seed.isEmpty());
return kdf.transform(rawKey(&seed), result);
}
bool CompositeKey::challenge(const QByteArray& seed, QByteArray& result) const
@@ -103,6 +154,7 @@ bool CompositeKey::challenge(const QByteArray& seed, QByteArray& result) const
for (const auto key : m_challengeResponseKeys) {
// if the device isn't present or fails, return an error
if (!key->challenge(seed)) {
qWarning("Failed to issue challenge");
return false;
}
cryptoHash.addData(key->rawKey());