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LibCrypto: Add Chacha20Poly1305

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stelar7 2023-09-25 19:46:21 +02:00 committed by Ali Mohammad Pur
parent 4c5b9fa6a2
commit 73ef102b01
6 changed files with 430 additions and 1 deletions
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1
Tests/LibCrypto/CMakeLists.txt
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@ -4,6 +4,7 @@ set(TEST_SOURCES
TestBigInteger.cpp
TestChecksum.cpp
TestChaCha20.cpp
TestChacha20Poly1305.cpp
TestCurves.cpp
TestEd25519.cpp
TestHash.cpp

209
Tests/LibCrypto/TestChacha20Poly1305.cpp Normal file
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@ -0,0 +1,209 @@
/*
* Copyright (c) 2023, stelar7 <dudedbz@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ByteBuffer.h>
#include <AK/String.h>
#include <LibCrypto/AEAD/ChaCha20Poly1305.h>
#include <LibTest/TestCase.h>
// https://datatracker.ietf.org/doc/html/rfc8439#section-2.6.2
TEST_CASE(test_keygen_vector_1)
{
u8 key[32] = {
0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f
};
u8 nonce[12] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07 };
u8 expected_raw[32] = {
0x8a, 0xd5, 0xa0, 0x8b, 0x90, 0x5f, 0x81, 0xcc, 0x81, 0x50, 0x40, 0x27, 0x4a, 0xb2, 0x94, 0x71,
0xa8, 0x33, 0xb6, 0x37, 0xe3, 0xfd, 0x0d, 0xa5, 0x08, 0xdb, 0xb8, 0xe2, 0xfd, 0xd1, 0xa6, 0x46
};
Crypto::AEAD::ChaCha20Poly1305 aead(ReadonlyBytes { key, 32 }, ReadonlyBytes { nonce, 12 });
auto otk = MUST(aead.poly1305_key());
auto expected = ReadonlyBytes { expected_raw, 32 };
EXPECT_EQ(otk.bytes(), expected);
}
// https://datatracker.ietf.org/doc/html/rfc8439#appendix-A.4
TEST_CASE(test_keygen_vector_2)
{
u8 key[32] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
u8 nonce[12] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
u8 expected_raw[32] = {
0x76, 0xb8, 0xe0, 0xad, 0xa0, 0xf1, 0x3d, 0x90, 0x40, 0x5d, 0x6a, 0xe5, 0x53, 0x86, 0xbd, 0x28,
0xbd, 0xd2, 0x19, 0xb8, 0xa0, 0x8d, 0xed, 0x1a, 0xa8, 0x36, 0xef, 0xcc, 0x8b, 0x77, 0x0d, 0xc7
};
Crypto::AEAD::ChaCha20Poly1305 aead(ReadonlyBytes { key, 32 }, ReadonlyBytes { nonce, 12 });
auto otk = MUST(aead.poly1305_key());
auto expected = ReadonlyBytes { expected_raw, 32 };
EXPECT_EQ(otk.bytes(), expected);
}
// https://datatracker.ietf.org/doc/html/rfc8439#appendix-A.4
TEST_CASE(test_keygen_vector_3)
{
u8 key[32] = {
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01
};
u8 nonce[12] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 };
u8 expected_raw[32] = {
0xec, 0xfa, 0x25, 0x4f, 0x84, 0x5f, 0x64, 0x74, 0x73, 0xd3, 0xcb, 0x14, 0x0d, 0xa9, 0xe8, 0x76,
0x06, 0xcb, 0x33, 0x06, 0x6c, 0x44, 0x7b, 0x87, 0xbc, 0x26, 0x66, 0xdd, 0xe3, 0xfb, 0xb7, 0x39
};
Crypto::AEAD::ChaCha20Poly1305 aead(ReadonlyBytes { key, 32 }, ReadonlyBytes { nonce, 12 });
auto otk = MUST(aead.poly1305_key());
auto expected = ReadonlyBytes { expected_raw, 32 };
EXPECT_EQ(otk.bytes(), expected);
}
// https://datatracker.ietf.org/doc/html/rfc8439#appendix-A.4
TEST_CASE(test_keygen_vector_4)
{
u8 key[32] = {
0x1c, 0x92, 0x40, 0xa5, 0xeb, 0x55, 0xd3, 0x8a, 0xf3, 0x33, 0x88, 0x86, 0x04, 0xf6, 0xb5, 0xf0,
0x47, 0x39, 0x17, 0xc1, 0x40, 0x2b, 0x80, 0x09, 0x9d, 0xca, 0x5c, 0xbc, 0x20, 0x70, 0x75, 0xc0
};
u8 nonce[12] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 };
u8 expected_raw[32] = {
0x96, 0x5e, 0x3b, 0xc6, 0xf9, 0xec, 0x7e, 0xd9, 0x56, 0x08, 0x08, 0xf4, 0xd2, 0x29, 0xf9, 0x4b,
0x13, 0x7f, 0xf2, 0x75, 0xca, 0x9b, 0x3f, 0xcb, 0xdd, 0x59, 0xde, 0xaa, 0xd2, 0x33, 0x10, 0xae
};
Crypto::AEAD::ChaCha20Poly1305 aead(ReadonlyBytes { key, 32 }, ReadonlyBytes { nonce, 12 });
auto otk = MUST(aead.poly1305_key());
auto expected = ReadonlyBytes { expected_raw, 32 };
EXPECT_EQ(otk.bytes(), expected);
}
// https://datatracker.ietf.org/doc/html/rfc8439#section-2.8.2
TEST_CASE(test_aead_encrypt_1)
{
auto plaintext = MUST(String::from_utf8("Ladies and Gentlemen of the class of '99: If I could offer you only one tip for the future, sunscreen would be it."sv));
u8 aad[12] = { 0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7 };
u8 key[32] = {
0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f
};
u8 nonce[12] = { 0x07, 0x00, 0x00, 0x00, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47 };
u8 expected_ciphertext[114] = {
0xd3, 0x1a, 0x8d, 0x34, 0x64, 0x8e, 0x60, 0xdb, 0x7b, 0x86, 0xaf, 0xbc, 0x53, 0xef, 0x7e, 0xc2,
0xa4, 0xad, 0xed, 0x51, 0x29, 0x6e, 0x08, 0xfe, 0xa9, 0xe2, 0xb5, 0xa7, 0x36, 0xee, 0x62, 0xd6,
0x3d, 0xbe, 0xa4, 0x5e, 0x8c, 0xa9, 0x67, 0x12, 0x82, 0xfa, 0xfb, 0x69, 0xda, 0x92, 0x72, 0x8b,
0x1a, 0x71, 0xde, 0x0a, 0x9e, 0x06, 0x0b, 0x29, 0x05, 0xd6, 0xa5, 0xb6, 0x7e, 0xcd, 0x3b, 0x36,
0x92, 0xdd, 0xbd, 0x7f, 0x2d, 0x77, 0x8b, 0x8c, 0x98, 0x03, 0xae, 0xe3, 0x28, 0x09, 0x1b, 0x58,
0xfa, 0xb3, 0x24, 0xe4, 0xfa, 0xd6, 0x75, 0x94, 0x55, 0x85, 0x80, 0x8b, 0x48, 0x31, 0xd7, 0xbc,
0x3f, 0xf4, 0xde, 0xf0, 0x8e, 0x4b, 0x7a, 0x9d, 0xe5, 0x76, 0xd2, 0x65, 0x86, 0xce, 0xc6, 0x4b,
0x61, 0x16
};
u8 expected_tag[16] = {
0x1a, 0xe1, 0x0b, 0x59, 0x4f, 0x09, 0xe2, 0x6a, 0x7e, 0x90, 0x2e, 0xcb, 0xd0, 0x60, 0x06, 0x91
};
auto ciphertext = ReadonlyBytes { expected_ciphertext, 114 };
auto tag = ReadonlyBytes { expected_tag, 16 };
Crypto::AEAD::ChaCha20Poly1305 aead(ReadonlyBytes { key, 32 }, ReadonlyBytes { nonce, 12 });
auto encrypted = MUST(aead.encrypt(ReadonlyBytes { aad, 12 }, plaintext.bytes()));
EXPECT_EQ(encrypted.size(), plaintext.bytes().size() + 16);
EXPECT_EQ(encrypted.bytes().slice(0, plaintext.bytes().size()), ciphertext);
EXPECT_EQ(encrypted.bytes().slice_from_end(16), tag);
}
// https://datatracker.ietf.org/doc/html/rfc8439#appendix-A.5
TEST_CASE(test_aead_decrypt_1)
{
u8 aad[12] = { 0xf3, 0x33, 0x88, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x4e, 0x91 };
u8 key[32] = {
0x1c, 0x92, 0x40, 0xa5, 0xeb, 0x55, 0xd3, 0x8a, 0xf3, 0x33, 0x88, 0x86, 0x04, 0xf6, 0xb5, 0xf0,
0x47, 0x39, 0x17, 0xc1, 0x40, 0x2b, 0x80, 0x09, 0x9d, 0xca, 0x5c, 0xbc, 0x20, 0x70, 0x75, 0xc0
};
u8 nonce[12] = { 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
u8 ciphertext[265] = {
0x64, 0xa0, 0x86, 0x15, 0x75, 0x86, 0x1a, 0xf4, 0x60, 0xf0, 0x62, 0xc7, 0x9b, 0xe6, 0x43, 0xbd,
0x5e, 0x80, 0x5c, 0xfd, 0x34, 0x5c, 0xf3, 0x89, 0xf1, 0x08, 0x67, 0x0a, 0xc7, 0x6c, 0x8c, 0xb2,
0x4c, 0x6c, 0xfc, 0x18, 0x75, 0x5d, 0x43, 0xee, 0xa0, 0x9e, 0xe9, 0x4e, 0x38, 0x2d, 0x26, 0xb0,
0xbd, 0xb7, 0xb7, 0x3c, 0x32, 0x1b, 0x01, 0x00, 0xd4, 0xf0, 0x3b, 0x7f, 0x35, 0x58, 0x94, 0xcf,
0x33, 0x2f, 0x83, 0x0e, 0x71, 0x0b, 0x97, 0xce, 0x98, 0xc8, 0xa8, 0x4a, 0xbd, 0x0b, 0x94, 0x81,
0x14, 0xad, 0x17, 0x6e, 0x00, 0x8d, 0x33, 0xbd, 0x60, 0xf9, 0x82, 0xb1, 0xff, 0x37, 0xc8, 0x55,
0x97, 0x97, 0xa0, 0x6e, 0xf4, 0xf0, 0xef, 0x61, 0xc1, 0x86, 0x32, 0x4e, 0x2b, 0x35, 0x06, 0x38,
0x36, 0x06, 0x90, 0x7b, 0x6a, 0x7c, 0x02, 0xb0, 0xf9, 0xf6, 0x15, 0x7b, 0x53, 0xc8, 0x67, 0xe4,
0xb9, 0x16, 0x6c, 0x76, 0x7b, 0x80, 0x4d, 0x46, 0xa5, 0x9b, 0x52, 0x16, 0xcd, 0xe7, 0xa4, 0xe9,
0x90, 0x40, 0xc5, 0xa4, 0x04, 0x33, 0x22, 0x5e, 0xe2, 0x82, 0xa1, 0xb0, 0xa0, 0x6c, 0x52, 0x3e,
0xaf, 0x45, 0x34, 0xd7, 0xf8, 0x3f, 0xa1, 0x15, 0x5b, 0x00, 0x47, 0x71, 0x8c, 0xbc, 0x54, 0x6a,
0x0d, 0x07, 0x2b, 0x04, 0xb3, 0x56, 0x4e, 0xea, 0x1b, 0x42, 0x22, 0x73, 0xf5, 0x48, 0x27, 0x1a,
0x0b, 0xb2, 0x31, 0x60, 0x53, 0xfa, 0x76, 0x99, 0x19, 0x55, 0xeb, 0xd6, 0x31, 0x59, 0x43, 0x4e,
0xce, 0xbb, 0x4e, 0x46, 0x6d, 0xae, 0x5a, 0x10, 0x73, 0xa6, 0x72, 0x76, 0x27, 0x09, 0x7a, 0x10,
0x49, 0xe6, 0x17, 0xd9, 0x1d, 0x36, 0x10, 0x94, 0xfa, 0x68, 0xf0, 0xff, 0x77, 0x98, 0x71, 0x30,
0x30, 0x5b, 0xea, 0xba, 0x2e, 0xda, 0x04, 0xdf, 0x99, 0x7b, 0x71, 0x4d, 0x6c, 0x6f, 0x2c, 0x29,
0xa6, 0xad, 0x5c, 0xb4, 0x02, 0x2b, 0x02, 0x70, 0x9b
};
u8 expected_plaintext[265] = {
0x49, 0x6e, 0x74, 0x65, 0x72, 0x6e, 0x65, 0x74, 0x2d, 0x44, 0x72, 0x61, 0x66, 0x74, 0x73, 0x20,
0x61, 0x72, 0x65, 0x20, 0x64, 0x72, 0x61, 0x66, 0x74, 0x20, 0x64, 0x6f, 0x63, 0x75, 0x6d, 0x65,
0x6e, 0x74, 0x73, 0x20, 0x76, 0x61, 0x6c, 0x69, 0x64, 0x20, 0x66, 0x6f, 0x72, 0x20, 0x61, 0x20,
0x6d, 0x61, 0x78, 0x69, 0x6d, 0x75, 0x6d, 0x20, 0x6f, 0x66, 0x20, 0x73, 0x69, 0x78, 0x20, 0x6d,
0x6f, 0x6e, 0x74, 0x68, 0x73, 0x20, 0x61, 0x6e, 0x64, 0x20, 0x6d, 0x61, 0x79, 0x20, 0x62, 0x65,
0x20, 0x75, 0x70, 0x64, 0x61, 0x74, 0x65, 0x64, 0x2c, 0x20, 0x72, 0x65, 0x70, 0x6c, 0x61, 0x63,
0x65, 0x64, 0x2c, 0x20, 0x6f, 0x72, 0x20, 0x6f, 0x62, 0x73, 0x6f, 0x6c, 0x65, 0x74, 0x65, 0x64,
0x20, 0x62, 0x79, 0x20, 0x6f, 0x74, 0x68, 0x65, 0x72, 0x20, 0x64, 0x6f, 0x63, 0x75, 0x6d, 0x65,
0x6e, 0x74, 0x73, 0x20, 0x61, 0x74, 0x20, 0x61, 0x6e, 0x79, 0x20, 0x74, 0x69, 0x6d, 0x65, 0x2e,
0x20, 0x49, 0x74, 0x20, 0x69, 0x73, 0x20, 0x69, 0x6e, 0x61, 0x70, 0x70, 0x72, 0x6f, 0x70, 0x72,
0x69, 0x61, 0x74, 0x65, 0x20, 0x74, 0x6f, 0x20, 0x75, 0x73, 0x65, 0x20, 0x49, 0x6e, 0x74, 0x65,
0x72, 0x6e, 0x65, 0x74, 0x2d, 0x44, 0x72, 0x61, 0x66, 0x74, 0x73, 0x20, 0x61, 0x73, 0x20, 0x72,
0x65, 0x66, 0x65, 0x72, 0x65, 0x6e, 0x63, 0x65, 0x20, 0x6d, 0x61, 0x74, 0x65, 0x72, 0x69, 0x61,
0x6c, 0x20, 0x6f, 0x72, 0x20, 0x74, 0x6f, 0x20, 0x63, 0x69, 0x74, 0x65, 0x20, 0x74, 0x68, 0x65,
0x6d, 0x20, 0x6f, 0x74, 0x68, 0x65, 0x72, 0x20, 0x74, 0x68, 0x61, 0x6e, 0x20, 0x61, 0x73, 0x20,
0x2f, 0xe2, 0x80, 0x9c, 0x77, 0x6f, 0x72, 0x6b, 0x20, 0x69, 0x6e, 0x20, 0x70, 0x72, 0x6f, 0x67,
0x72, 0x65, 0x73, 0x73, 0x2e, 0x2f, 0xe2, 0x80, 0x9d
};
u8 expected_tag[16] = {
0xee, 0xad, 0x9d, 0x67, 0x89, 0x0c, 0xbb, 0x22, 0x39, 0x23, 0x36, 0xfe, 0xa1, 0x85, 0x1f, 0x38
};
auto plaintext = ReadonlyBytes { expected_plaintext, 265 };
auto tag = ReadonlyBytes { expected_tag, 16 };
Crypto::AEAD::ChaCha20Poly1305 aead(ReadonlyBytes { key, 32 }, ReadonlyBytes { nonce, 12 });
auto decrypted = MUST(aead.decrypt(ReadonlyBytes { aad, 12 }, ReadonlyBytes { ciphertext, 265 }));
EXPECT_EQ(decrypted.size(), plaintext.size() + 16);
EXPECT_EQ(decrypted.bytes().slice(0, plaintext.size()), plaintext);
EXPECT_EQ(decrypted.bytes().slice_from_end(16), tag);
}
TEST_CASE(test_aead_encrypt_and_decrypt)
{
auto plaintext = MUST(String::from_utf8("Well, hello friends :)"sv));
u8 aad[12] = { 0x50, 0x51, 0x52, 0x53, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7 };
u8 key[32] = {
0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f
};
u8 nonce[12] = { 0x07, 0x00, 0x00, 0x00, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47 };
Crypto::AEAD::ChaCha20Poly1305 aead(ReadonlyBytes { key, 32 }, ReadonlyBytes { nonce, 12 });
auto encrypted = MUST(aead.encrypt(ReadonlyBytes { aad, 12 }, plaintext.bytes()));
auto decrypted = MUST(aead.decrypt(ReadonlyBytes { aad, 12 }, encrypted.bytes().slice(0, encrypted.bytes().size() - 16)));
EXPECT(Crypto::AEAD::ChaCha20Poly1305::verify_tag(encrypted, decrypted));
EXPECT_EQ(decrypted.bytes().slice(0, encrypted.bytes().size() - 16), plaintext.bytes());
}

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Userland/Libraries/LibCrypto/AEAD/ChaCha20Poly1305.cpp Normal file
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/*
* Copyright (c) 2023, stelar7 <dudedbz@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ByteReader.h>
#include <AK/Endian.h>
#include <LibCrypto/AEAD/ChaCha20Poly1305.h>
#include <LibCrypto/Authentication/Poly1305.h>
#include <LibCrypto/Cipher/ChaCha20.h>
namespace Crypto::AEAD {
// https://datatracker.ietf.org/doc/html/rfc8439#section-2.6
ErrorOr<ByteBuffer> ChaCha20Poly1305::poly1305_key()
{
Crypto::Cipher::ChaCha20 cipher(m_key, m_nonce, 0);
cipher.generate_block();
auto state = cipher.block();
return TRY(ByteBuffer::copy(state.slice(0, 32)));
}
// https://datatracker.ietf.org/doc/html/rfc8439#section-2.8
ErrorOr<ByteBuffer> ChaCha20Poly1305::encrypt(ReadonlyBytes aad, ReadonlyBytes input_plaintext)
{
// First, a Poly1305 one-time key is generated from the 256-bit key
// and nonce using the procedure described in Section 2.6.
auto otk = TRY(poly1305_key());
// Next, the ChaCha20 encryption function is called to encrypt the
// plaintext, using the same key and nonce, and with the initial
// counter set to 1.
auto ciphertext_buffer = TRY(ByteBuffer::create_zeroed(input_plaintext.size()));
auto ciphertext = ciphertext_buffer.bytes();
auto chacha = Crypto::Cipher::ChaCha20(m_key, m_nonce, 1);
chacha.encrypt(input_plaintext, ciphertext);
// Finally, the Poly1305 function is called with the Poly1305 key
// calculated above, and a message constructed as a concatenation of
// the following:
auto mac_data = TRY(ByteBuffer::create_zeroed(0));
auto buffer_size = aad.size() + pad_to_16(aad) + ciphertext_buffer.size() + pad_to_16(ciphertext_buffer) + sizeof(u64) + sizeof(u64);
mac_data.ensure_capacity(buffer_size);
// The AAD
mac_data.append(aad);
// padding1 -- the padding is up to 15 zero bytes, and it brings
// the total length so far to an integral multiple of 16. If the
// length of the AAD was already an integral multiple of 16 bytes,
// this field is zero-length.
for (size_t i = 0; i < pad_to_16(aad); ++i)
mac_data.append(0);
// The ciphertext
mac_data.append(ciphertext);
// padding2 -- the padding is up to 15 zero bytes, and it brings
// the total length so far to an integral multiple of 16. If the
// length of the ciphertext was already an integral multiple of 16
// bytes, this field is zero-length.
for (size_t i = 0; i < pad_to_16(ciphertext); ++i)
mac_data.append(0);
u8 placeholder[8] = { 0 };
// The length of the additional data in octets (as a 64-bit little-endian integer).
mac_data.append(ReadonlyBytes { placeholder, 8 });
ByteReader::store(static_cast<u8*>(mac_data.end_pointer()) - sizeof(u64), AK::convert_between_host_and_little_endian(static_cast<u64>(aad.size())));
// The length of the ciphertext in octets (as a 64-bit little-endian integer).
mac_data.append(ReadonlyBytes { placeholder, 8 });
ByteReader::store(static_cast<u8*>(mac_data.end_pointer()) - sizeof(u64), AK::convert_between_host_and_little_endian(static_cast<u64>(ciphertext.size())));
Crypto::Authentication::Poly1305 mac_function(otk);
mac_function.update(mac_data.bytes());
auto tag = TRY(mac_function.digest());
// The output from the AEAD is the concatenation of:
auto result = TRY(ByteBuffer::create_zeroed(0));
result.ensure_capacity(ciphertext.size() + tag.size());
// A ciphertext of the same length as the plaintext.
result.append(ciphertext);
// A 128-bit tag, which is the output of the Poly1305 function.
result.append(tag);
return result;
}
// https://datatracker.ietf.org/doc/html/rfc8439#section-2.8
ErrorOr<ByteBuffer> ChaCha20Poly1305::decrypt(ReadonlyBytes aad, ReadonlyBytes ciphertext)
{
// Decryption is similar with the following differences:
// o The roles of ciphertext and plaintext are reversed, so the
// ChaCha20 encryption function is applied to the ciphertext,
// producing the plaintext.
// o The Poly1305 function is still run on the AAD and the ciphertext,
// not the plaintext.
// First, a Poly1305 one-time key is generated from the 256-bit key
// and nonce using the procedure described in Section 2.6.
auto otk = TRY(poly1305_key());
// Next, the ChaCha20 encryption function is called to decrypt the
// ciphertext, using the same key and nonce, and with the initial
// counter set to 1.
auto chacha = Crypto::Cipher::ChaCha20(m_key, m_nonce, 1);
auto plaintext_buffer = TRY(ByteBuffer::create_zeroed(ciphertext.size()));
auto plaintext = plaintext_buffer.bytes();
chacha.encrypt(ciphertext, plaintext);
// Finally, the Poly1305 function is called with the Poly1305 key
// calculated above, and a message constructed as a concatenation of
// the following:
auto mac_data = TRY(ByteBuffer::create_zeroed(0));
auto buffer_size = aad.size() + pad_to_16(aad) + ciphertext.size() + pad_to_16(ciphertext) + sizeof(u64) + sizeof(u64);
mac_data.ensure_capacity(buffer_size);
// The AAD
mac_data.append(aad);
// padding1 -- the padding is up to 15 zero bytes, and it brings
// the total length so far to an integral multiple of 16. If the
// length of the AAD was already an integral multiple of 16 bytes,
// this field is zero-length.
for (size_t i = 0; i < pad_to_16(aad); ++i)
mac_data.append(0);
// The ciphertext
mac_data.append(ciphertext);
// padding2 -- the padding is up to 15 zero bytes, and it brings
// the total length so far to an integral multiple of 16. If the
// length of the ciphertext was already an integral multiple of 16
// bytes, this field is zero-length.
for (size_t i = 0; i < pad_to_16(ciphertext); ++i)
mac_data.append(0);
u8 placeholder[8] = { 0 };
// The length of the additional data in octets (as a 64-bit little-endian integer).
mac_data.append(ReadonlyBytes { placeholder, 8 });
ByteReader::store(static_cast<u8*>(mac_data.end_pointer()) - sizeof(u64), AK::convert_between_host_and_little_endian(static_cast<u64>(aad.size())));
// The length of the ciphertext in octets (as a 64-bit little-endian integer).
mac_data.append(ReadonlyBytes { placeholder, 8 });
ByteReader::store(static_cast<u8*>(mac_data.end_pointer()) - sizeof(u64), AK::convert_between_host_and_little_endian(static_cast<u64>(ciphertext.size())));
Crypto::Authentication::Poly1305 mac_function(otk);
mac_function.update(mac_data.bytes());
auto tag = TRY(mac_function.digest());
// The output from the AEAD is the concatenation of:
auto result = TRY(ByteBuffer::create_zeroed(0));
result.ensure_capacity(plaintext.size() + tag.size());
// A plaintext of the same length as the ciphertext.
result.append(plaintext);
// A 128-bit tag, which is the output of the Poly1305 function.
result.append(tag);
return result;
}
// https://datatracker.ietf.org/doc/html/rfc8439#section-4
bool ChaCha20Poly1305::verify_tag(ReadonlyBytes encrypted, ReadonlyBytes decrypted)
{
// With online protocols, implementation MUST use a constant-time comparison function rather
// than relying on optimized but insecure library functions such as the C language's memcmp().
auto encrypted_tag = encrypted.slice_from_end(16);
auto decrypted_tag = decrypted.slice_from_end(16);
if (encrypted_tag.size() != decrypted_tag.size())
return false;
auto result = 0;
for (size_t i = 0; i < encrypted_tag.size(); ++i)
result |= encrypted_tag[i] ^ decrypted_tag[i];
return result == 0;
}
}

35
Userland/Libraries/LibCrypto/AEAD/ChaCha20Poly1305.h Normal file
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@ -0,0 +1,35 @@
/*
* Copyright (c) 2023, stelar7 <dudedbz@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/ByteBuffer.h>
namespace Crypto::AEAD {
class ChaCha20Poly1305 {
public:
explicit ChaCha20Poly1305(ReadonlyBytes key, ReadonlyBytes nonce)
{
m_key = MUST(ByteBuffer::copy(key));
m_nonce = MUST(ByteBuffer::copy(nonce));
}
ErrorOr<ByteBuffer> encrypt(ReadonlyBytes aad, ReadonlyBytes plaintext);
ErrorOr<ByteBuffer> decrypt(ReadonlyBytes aad, ReadonlyBytes ciphertext);
ErrorOr<ByteBuffer> poly1305_key();
static bool verify_tag(ReadonlyBytes encrypted, ReadonlyBytes decrypted);
private:
u8 pad_to_16(ReadonlyBytes data)
{
return 16 - (data.size() % 16);
}
ByteBuffer m_key;
ByteBuffer m_nonce;
};
}

1
Userland/Libraries/LibCrypto/CMakeLists.txt
View file

@ -1,6 +1,7 @@
add_compile_options(-Wvla)
set(SOURCES
AEAD/ChaCha20Poly1305.cpp
ASN1/ASN1.cpp
ASN1/DER.cpp
ASN1/PEM.cpp

3
Userland/Libraries/LibCrypto/Cipher/ChaCha20.h
View file

@ -19,10 +19,11 @@ public:
void encrypt(ReadonlyBytes input, Bytes& output);
void decrypt(ReadonlyBytes input, Bytes& output);
void generate_block();
ReadonlyBytes block() const { return { m_block, 64 }; }
private:
void run_cipher(ReadonlyBytes input, Bytes& output);
void generate_block();
ALWAYS_INLINE void do_quarter_round(u32& a, u32& b, u32& c, u32& d);
u32 m_state[16] {};