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LibCrypto: Templatise CTR<T> on the increment function

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This commit is contained in:
AnotherTest 2020-07-29 04:31:52 +04:30 • committed by Andreas Kling
parent ed2689c00a
commit b9822d606d
1 changed files with 21 additions and 16 deletions
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37
Libraries/LibCrypto/Cipher/Mode/CTR.h
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@ -88,7 +88,22 @@ namespace Cipher {
* TODO: Implement other counters?
*/
template<typename T>
struct IncrementInplace {
void operator()(Bytes& in) const
{
for (size_t i = in.size(); i > 0;) {
--i;
if (in[i] == (u8)-1) {
in[i] = 0;
} else {
in[i]++;
break;
}
}
}
};
template<typename T, typename IncrementFunctionType = IncrementInplace>
class CTR : public Mode<T> {
public:
constexpr static size_t IVSizeInBits = 128;
@ -99,8 +114,8 @@ public:
// Encryption, even when decrypting AES-CTR.
// TODO: How to deal with ciphers that take different arguments?
template<typename KeyType, typename... Args>
explicit constexpr CTR<T>(const KeyType& user_key, size_t key_bits, Intent = Intent::Encryption, Args... args)
: Mode<T>(user_key, key_bits, args...)
explicit constexpr CTR(const KeyType& user_key, size_t key_bits, Intent = Intent::Encryption, Args... args)
: Mode<T>(user_key, key_bits, Intent::Encryption, args...)
{
}
@ -136,18 +151,8 @@ private:
u8 m_ivec_storage[IVSizeInBits / 8];
typename T::BlockType m_cipher_block {};
static void increment_inplace(Bytes& in)
{
for (size_t i = in.size(); i > 0;) {
--i;
if (in[i] == (u8)-1) {
in[i] = 0;
} else {
in[i]++;
break;
}
}
}
protected:
constexpr static IncrementFunctionType increment {};
void encrypt_or_stream(const ReadonlyBytes* in, Bytes& out, const Bytes& ivec, Bytes* ivec_out = nullptr)
{
@ -188,7 +193,7 @@ private:
ASSERT(offset + write_size <= out.size());
__builtin_memcpy(out.offset(offset), m_cipher_block.get().data(), write_size);
increment_inplace(iv);
increment(iv);
length -= write_size;
offset += write_size;
}