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LibWeb: Add support for AES-GCM encrypt and decrypt
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Adds ~400 WPT test passes.
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@devgianlu
devgianlu committed Dec 16, 2024
1 parent e4614e2 commit 95053b2
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Showing 12 changed files with 1,626 additions and 98 deletions.
49 changes: 24 additions & 25 deletions Libraries/LibWeb/Crypto/CryptoAlgorithms.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2021,11 +2021,15 @@ WebIDL::ExceptionOr<GC::Ref<JS::ArrayBuffer>> AesGcm::encrypt(AlgorithmParams co
{
auto const& normalized_algorithm = static_cast<AesGcmParams const&>(params);

// FIXME: 1. If plaintext has a length greater than 2^39 - 256 bytes, then throw an OperationError.
// 1. If plaintext has a length greater than 2^39 - 256 bytes, then throw an OperationError.
if (plaintext.size() > (1ULL << 39) - 256)
return WebIDL::OperationError::create(m_realm, "Invalid plaintext length"_string);

// FIXME: 2. If the iv member of normalizedAlgorithm has a length greater than 2^64 - 1 bytes, then throw an OperationError.
// 2. If the iv member of normalizedAlgorithm has a length greater than 2^64 - 1 bytes, then throw an OperationError.
// NOTE: This is not possible

// FIXME: 3. If the additionalData member of normalizedAlgorithm is present and has a length greater than 2^64 - 1 bytes, then throw an OperationError.
// 3. If the additionalData member of normalizedAlgorithm is present and has a length greater than 2^64 - 1 bytes, then throw an OperationError.
// NOTE: This is not possible

// 4. If the tagLength member of normalizedAlgorithm is not present: Let tagLength be 128.
auto tag_length = 0;
Expand Down Expand Up @@ -2055,19 +2059,16 @@ WebIDL::ExceptionOr<GC::Ref<JS::ArrayBuffer>> AesGcm::encrypt(AlgorithmParams co
auto key_bytes = key->handle().get<ByteBuffer>();

::Crypto::Cipher::AESCipher::GCMMode cipher(key_bytes, key_length, ::Crypto::Cipher::Intent::Encryption);
ByteBuffer ciphertext = TRY_OR_THROW_OOM(m_realm->vm(), ByteBuffer::create_zeroed(plaintext.size()));
ByteBuffer tag = TRY_OR_THROW_OOM(m_realm->vm(), ByteBuffer::create_zeroed(tag_length / 8));
[[maybe_unused]] Bytes ciphertext_span = ciphertext.bytes();
[[maybe_unused]] Bytes tag_span = tag.bytes();
auto ciphertext = TRY_OR_THROW_OOM(m_realm->vm(), ByteBuffer::create_zeroed(plaintext.size()));
auto tag = TRY_OR_THROW_OOM(m_realm->vm(), ByteBuffer::create_zeroed(tag_length / 8));

// FIXME: cipher.encrypt(plaintext, ciphertext_span, normalized_algorithm.iv, additional_data, tag_span);
return WebIDL::NotSupportedError::create(m_realm, "AES GCM encryption not yet implemented"_string);
cipher.encrypt(plaintext, ciphertext.bytes(), normalized_algorithm.iv, additional_data, tag.bytes());

// 7. Let ciphertext be equal to C | T, where '|' denotes concatenation.
// TRY_OR_THROW_OOM(m_realm->vm(), ciphertext.try_append(tag));
TRY_OR_THROW_OOM(m_realm->vm(), ciphertext.try_append(tag));

// 8. Return the result of creating an ArrayBuffer containing ciphertext.
// return JS::ArrayBuffer::create(m_realm, ciphertext);
return JS::ArrayBuffer::create(m_realm, ciphertext);
}

WebIDL::ExceptionOr<GC::Ref<JS::ArrayBuffer>> AesGcm::decrypt(AlgorithmParams const& params, GC::Ref<CryptoKey> key, ByteBuffer const& ciphertext)
Expand All @@ -2092,16 +2093,18 @@ WebIDL::ExceptionOr<GC::Ref<JS::ArrayBuffer>> AesGcm::decrypt(AlgorithmParams co
if (ciphertext.size() < tag_length / 8)
return WebIDL::OperationError::create(m_realm, "Invalid ciphertext length"_string);

// FIXME: 3. If the iv member of normalizedAlgorithm has a length greater than 2^64 - 1 bytes, then throw an OperationError.
// 3. If the iv member of normalizedAlgorithm has a length greater than 2^64 - 1 bytes, then throw an OperationError.
// NOTE: This is not possible

// FIXME: 4. If the additionalData member of normalizedAlgorithm is present and has a length greater than 2^64 - 1 bytes, then throw an OperationError.
// 4. If the additionalData member of normalizedAlgorithm is present and has a length greater than 2^64 - 1 bytes, then throw an OperationError.
// NOTE: This is not possible

// 5. Let tag be the last tagLength bits of ciphertext.
auto tag_bits = tag_length / 8;
auto tag = TRY_OR_THROW_OOM(m_realm->vm(), ciphertext.slice(ciphertext.size() - tag_bits, tag_bits));
auto tag_bytes = tag_length / 8;
auto tag = TRY_OR_THROW_OOM(m_realm->vm(), ciphertext.slice(ciphertext.size() - tag_bytes, tag_bytes));

// 6. Let actualCiphertext be the result of removing the last tagLength bits from ciphertext.
auto actual_ciphertext = TRY_OR_THROW_OOM(m_realm->vm(), ciphertext.slice(0, ciphertext.size() - tag_bits));
auto actual_ciphertext = TRY_OR_THROW_OOM(m_realm->vm(), ciphertext.slice(0, ciphertext.size() - tag_bytes));

// 7. Let additionalData be the contents of the additionalData member of normalizedAlgorithm if present or the empty octet string otherwise.
auto additional_data = normalized_algorithm.additional_data.value_or(ByteBuffer {});
Expand All @@ -2118,22 +2121,18 @@ WebIDL::ExceptionOr<GC::Ref<JS::ArrayBuffer>> AesGcm::decrypt(AlgorithmParams co
auto key_bytes = key->handle().get<ByteBuffer>();

::Crypto::Cipher::AESCipher::GCMMode cipher(key_bytes, key_length, ::Crypto::Cipher::Intent::Decryption);
ByteBuffer plaintext = TRY_OR_THROW_OOM(m_realm->vm(), ByteBuffer::create_zeroed(actual_ciphertext.size()));
[[maybe_unused]] Bytes plaintext_span = plaintext.bytes();
[[maybe_unused]] Bytes actual_ciphertext_span = actual_ciphertext.bytes();
[[maybe_unused]] Bytes tag_span = tag.bytes();
auto plaintext = TRY_OR_THROW_OOM(m_realm->vm(), ByteBuffer::create_zeroed(actual_ciphertext.size()));

// FIXME: auto result = cipher.decrypt(ciphertext, plaintext_span, normalized_algorithm.iv, additional_data, tag_span);
return WebIDL::NotSupportedError::create(m_realm, "AES GCM decryption not yet implemented"_string);
auto result = cipher.decrypt(actual_ciphertext.bytes(), plaintext.bytes(), normalized_algorithm.iv, additional_data, tag.bytes());

// If the result of the algorithm is the indication of inauthenticity, "FAIL": throw an OperationError
// if (result == ::Crypto::VerificationConsistency::Inconsistent)
// return WebIDL::OperationError::create(m_realm, "Decryption failed"_string);
if (result == ::Crypto::VerificationConsistency::Inconsistent)
return WebIDL::OperationError::create(m_realm, "Decryption failed"_string);

// Otherwise: Let plaintext be the output P of the Authenticated Decryption Function.

// 9. Return the result of creating an ArrayBuffer containing plaintext.
// return JS::ArrayBuffer::create(m_realm, plaintext);
return JS::ArrayBuffer::create(m_realm, plaintext);
}

WebIDL::ExceptionOr<Variant<GC::Ref<CryptoKey>, GC::Ref<CryptoKeyPair>>> AesGcm::generate_key(AlgorithmParams const& params, bool extractable, Vector<Bindings::KeyUsage> const& key_usages)
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