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LibCrypto: Implement and test CTR decryption

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This commit is contained in:
Ben Wiederhake 2020-07-26 05:40:07 +02:00 • committed by Andreas Kling
parent a51cbc2978
commit a296020e03
2 changed files with 41 additions and 8 deletions
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13
Libraries/LibCrypto/Cipher/Mode/CTR.h
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@ -95,9 +95,12 @@ public:
virtual ~CTR() { } virtual ~CTR() { }
// Must intercept `Intent`, because AES must always be set to
// Encryption, even when decrypting AES-CTR.
// TODO: How to deal with ciphers that take different arguments?
template<typename... Args> template<typename... Args>
explicit constexpr CTR<T>(Args... args) explicit constexpr CTR<T>(const ByteBuffer& user_key, size_t key_bits, Intent = Intent::Encryption, Args... args)
: Mode<T>(args...) : Mode<T>(user_key, key_bits, args...)
{ {
} }
@ -125,10 +128,8 @@ public:
virtual void decrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override virtual void decrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override
{ {
(void)in; // XOR (and thus CTR) is the most symmetric mode.
(void)out; this->encrypt(in, out, ivec);
(void)ivec;
// FIXME: Implement CTR decryption when it is needed.
} }
private: private:

36
Userland/test-crypto.cpp
View file

@ -869,8 +869,40 @@ void aes_ctr_test_encrypt()
void aes_ctr_test_decrypt() void aes_ctr_test_decrypt()
{ {
// FIXME Test not implemented yet auto test_it = [](auto key, auto ivec, auto in, auto out_expected) {
// Also, CTR implementation not done yet, even though it's trivial: Just ignore "intent". // nonce is already included in ivec.
Crypto::Cipher::AESCipher::CTRMode cipher(key, 8 * key.size(), Crypto::Cipher::Intent::Decryption);
ByteBuffer out_actual = ByteBuffer::create_zeroed(in.size());
cipher.decrypt(in, out_actual, ivec);
if (out_expected.size() != out_actual.size()) {
FAIL(size mismatch);
printf("Expected %zu bytes but got %zu\n", out_expected.size(), out_actual.size());
print_buffer(out_actual, Crypto::Cipher::AESCipher::block_size());
} else if (memcmp(out_expected.data(), out_actual.data(), out_expected.size()) != 0) {
FAIL(invalid data);
print_buffer(out_actual, Crypto::Cipher::AESCipher::block_size());
} else
PASS;
};
// From RFC 3686, Section 6
{
// Test Vector #1
I_TEST((AES CTR 16 octets with 128 bit key | Decrypt))
u8 key[] {
0xae, 0x68, 0x52, 0xf8, 0x12, 0x10, 0x67, 0xcc, 0x4b, 0xf7, 0xa5, 0x76, 0x55, 0x77, 0xf3, 0x9e
};
u8 ivec[] {
0x00, 0x00, 0x00, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 + 1 // See CTR.h
};
u8 out[] {
0x53, 0x69, 0x6e, 0x67, 0x6c, 0x65, 0x20, 0x62, 0x6c, 0x6f, 0x63, 0x6b, 0x20, 0x6d, 0x73, 0x67
};
u8 in[] {
0xe4, 0x09, 0x5d, 0x4f, 0xb7, 0xa7, 0xb3, 0x79, 0x2d, 0x61, 0x75, 0xa3, 0x26, 0x13, 0x11, 0xb8
};
test_it(AS_BB(key), AS_BB(ivec), AS_BB(in), AS_BB(out));
}
// If encryption works, then decryption works, too.
} }
int md5_tests() int md5_tests()