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LibWeb: Implement CryptoAlgorithms and KeyAlgorithms for big-endian systems #24689

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LibWeb: Implement CryptoAlgorithms and KeyAlgorithms for big-endian systems #24689

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LibWeb: Implement CryptoAlgorithms for big-endian
sideeffect42 Jul 3, 2024
c29a629
LibWeb: Implement KeyAlgorithms for big-endian
sideeffect42 Jul 3, 2024
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67 changes: 37 additions & 30 deletions Userland/Libraries/LibWeb/Crypto/CryptoAlgorithms.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -44,8 +44,6 @@ AlgorithmMethods::~AlgorithmMethods() = default;
// https://w3c.github.io/webcrypto/#big-integer
static ::Crypto::UnsignedBigInteger big_integer_from_api_big_integer(JS::GCPtr<JS::Uint8Array> const& big_integer)
{
static_assert(AK::HostIsLittleEndian, "This method needs special treatment for BE");

// The BigInteger typedef is a Uint8Array that holds an arbitrary magnitude unsigned integer
// **in big-endian order**. Values read from the API SHALL have minimal typed array length
// (that is, at most 7 leading zero bits, except the value 0 which shall have length 8 bits).
Expand All @@ -55,24 +53,25 @@ static ::Crypto::UnsignedBigInteger big_integer_from_api_big_integer(JS::GCPtr<J

::Crypto::UnsignedBigInteger result(0);
if (buffer.size() > 0) {
if constexpr (AK::HostIsLittleEndian) {
// We need to reverse the buffer to get it into little-endian order
Vector<u8, 32> reversed_buffer;
reversed_buffer.resize(buffer.size());
for (size_t i = 0; i < buffer.size(); ++i) {
reversed_buffer[buffer.size() - i - 1] = buffer[i];
}

// We need to reverse the buffer to get it into little-endian order
Vector<u8, 32> reversed_buffer;
reversed_buffer.resize(buffer.size());
for (size_t i = 0; i < buffer.size(); ++i) {
reversed_buffer[buffer.size() - i - 1] = buffer[i];
return ::Crypto::UnsignedBigInteger::import_data(reversed_buffer.data(), reversed_buffer.size());
} else {
return ::Crypto::UnsignedBigInteger::import_data(buffer.data(), buffer.size());
}

result = ::Crypto::UnsignedBigInteger::import_data(reversed_buffer.data(), reversed_buffer.size());
}
return result;
return ::Crypto::UnsignedBigInteger(0);
}

// https://www.rfc-editor.org/rfc/rfc7518#section-2
ErrorOr<String> base64_url_uint_encode(::Crypto::UnsignedBigInteger integer)
{
static_assert(AK::HostIsLittleEndian, "This code assumes little-endian");

// The representation of a positive or zero integer value as the
// base64url encoding of the value's unsigned big-endian
// representation as an octet sequence. The octet sequence MUST
Expand All @@ -85,15 +84,20 @@ ErrorOr<String> base64_url_uint_encode(::Crypto::UnsignedBigInteger integer)
bool const remove_leading_zeroes = true;
auto data_size = integer.export_data(bytes.span(), remove_leading_zeroes);

auto data_slice = bytes.bytes().slice(bytes.size() - data_size, data_size);
auto data_slice_be = bytes.bytes().slice(bytes.size() - data_size, data_size);

// We need to encode the integer's big endian representation as a base64 string
Vector<u8, 32> byte_swapped_data;
byte_swapped_data.ensure_capacity(data_size);
for (size_t i = 0; i < data_size; ++i)
byte_swapped_data.append(data_slice[data_size - i - 1]);

auto encoded = TRY(encode_base64url(byte_swapped_data));
String encoded;
if constexpr (AK::HostIsLittleEndian) {
// We need to encode the integer's big endian representation as a base64 string
Vector<u8, 32> data_slice_cpu;
data_slice_cpu.ensure_capacity(data_size);
for (size_t i = 0; i < data_size; ++i) {
data_slice_cpu.append(data_slice_be[data_size - i - 1]);
}
encoded = TRY(encode_base64url(data_slice_cpu));
} else {
encoded = TRY(encode_base64url(data_slice_be));
}

// FIXME: create a version of encode_base64url that omits padding bytes
if (auto first_padding_byte = encoded.find_byte_offset('='); first_padding_byte.has_value())
Expand All @@ -104,7 +108,6 @@ ErrorOr<String> base64_url_uint_encode(::Crypto::UnsignedBigInteger integer)
WebIDL::ExceptionOr<::Crypto::UnsignedBigInteger> base64_url_uint_decode(JS::Realm& realm, String const& base64_url_string)
{
auto& vm = realm.vm();
static_assert(AK::HostIsLittleEndian, "This code assumes little-endian");

// FIXME: Create a version of decode_base64url that ignores padding inconsistencies
auto padded_string = base64_url_string;
Expand All @@ -118,15 +121,19 @@ WebIDL::ExceptionOr<::Crypto::UnsignedBigInteger> base64_url_uint_decode(JS::Rea
return vm.throw_completion<JS::InternalError>(vm.error_message(::JS::VM::ErrorMessage::OutOfMemory));
return WebIDL::DataError::create(realm, MUST(String::formatted("base64 decode: {}", base64_bytes_or_error.release_error())));
}
auto base64_bytes = base64_bytes_or_error.release_value();

// We need to swap the integer's big-endian representation to little endian in order to import it
Vector<u8, 32> byte_swapped_data;
byte_swapped_data.ensure_capacity(base64_bytes.size());
for (size_t i = 0; i < base64_bytes.size(); ++i)
byte_swapped_data.append(base64_bytes[base64_bytes.size() - i - 1]);

return ::Crypto::UnsignedBigInteger::import_data(byte_swapped_data.data(), byte_swapped_data.size());
auto base64_bytes_be = base64_bytes_or_error.release_value();

if constexpr (AK::HostIsLittleEndian) {
// We need to swap the integer's big-endian representation to little endian in order to import it
Vector<u8, 32> base64_bytes_cpu;
base64_bytes_cpu.ensure_capacity(base64_bytes_be.size());
for (size_t i = 0; i < base64_bytes_be.size(); ++i) {
base64_bytes_cpu.append(base64_bytes_be[base64_bytes_be.size() - i - 1]);
}
return ::Crypto::UnsignedBigInteger::import_data(base64_bytes_cpu.data(), base64_bytes_cpu.size());
} else {
return ::Crypto::UnsignedBigInteger::import_data(base64_bytes_be.data(), base64_bytes_be.size());
}
}

// https://w3c.github.io/webcrypto/#concept-parse-an-asn1-structure
Expand Down
23 changes: 13 additions & 10 deletions Userland/Libraries/LibWeb/Crypto/KeyAlgorithms.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -90,26 +90,29 @@ void RsaKeyAlgorithm::visit_edges(Visitor& visitor)

WebIDL::ExceptionOr<void> RsaKeyAlgorithm::set_public_exponent(::Crypto::UnsignedBigInteger exponent)
{
static_assert(AK::HostIsLittleEndian, "This code assumes a little endian host");

auto& realm = this->realm();
auto& vm = this->vm();

auto bytes = TRY_OR_THROW_OOM(vm, ByteBuffer::create_uninitialized(exponent.trimmed_byte_length()));

bool const remove_leading_zeroes = true;
auto data_size = exponent.export_data(bytes.span(), remove_leading_zeroes);
auto data_slice = bytes.bytes().slice(bytes.size() - data_size, data_size);
auto data_slice_be = bytes.bytes().slice(bytes.size() - data_size, data_size);

// The BigInteger typedef from the WebCrypto spec requires the bytes in the Uint8Array be ordered in Big Endian

Vector<u8, 32> byte_swapped_data;
byte_swapped_data.ensure_capacity(data_size);
for (size_t i = 0; i < data_size; ++i)
byte_swapped_data.append(data_slice[data_size - i - 1]);

m_public_exponent = TRY(JS::Uint8Array::create(realm, byte_swapped_data.size()));
m_public_exponent->viewed_array_buffer()->buffer().overwrite(0, byte_swapped_data.data(), byte_swapped_data.size());
if constexpr (AK::HostIsLittleEndian) {
Vector<u8, 32> data_slice_le;
data_slice_le.ensure_capacity(data_size);
for (size_t i = 0; i < data_size; ++i) {
data_slice_le.append(data_slice_be[data_size - i - 1]);
}
m_public_exponent = TRY(JS::Uint8Array::create(realm, data_slice_le.size()));
m_public_exponent->viewed_array_buffer()->buffer().overwrite(0, data_slice_le.data(), data_slice_le.size());
} else {
m_public_exponent = TRY(JS::Uint8Array::create(realm, data_slice_be.size()));
m_public_exponent->viewed_array_buffer()->buffer().overwrite(0, data_slice_be.data(), data_slice_be.size());
}

return {};
}
Expand Down