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V5.1.0
- Added support for HKDF (HMAC-based Key Derivation Function) - Added support for X25519 operations, including ScalarMultBase and ScalarMult
1 parent 9b93cad commit d6e82d4

27 files changed

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‎CHANGELOG.md‎

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## 5.1.0
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- Added support for HKDF (HMAC-based Key Derivation Function)
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- Added support for X25519 operations, including ScalarMultBase and ScalarMult
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## 5.0.0
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- Ported the Bitcoin secp256k1 cryptographic library to Dart.

‎example/pubspec.lock‎

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@@ -44,7 +44,7 @@ packages:
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path: ".."
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relative: true
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source: path
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version: "4.3.0"
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version: "5.1.0"
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boolean_selector:
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dependency: transitive
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description:
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url: "https://pub.dev"
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source: hosted
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version: "3.0.5"
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cryptography:
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dependency: transitive
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description:
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name: cryptography
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sha256: d146b76d33d94548cf035233fbc2f4338c1242fa119013bead807d033fc4ae05
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url: "https://pub.dev"
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source: hosted
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version: "2.7.0"
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cupertino_icons:
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dependency: "direct main"
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description:
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url: "https://pub.dev"
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source: hosted
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version: "1.0.8"
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ffi:
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dependency: transitive
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description:
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name: ffi
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sha256: "289279317b4b16eb2bb7e271abccd4bf84ec9bdcbe999e278a94b804f5630418"
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url: "https://pub.dev"
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source: hosted
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version: "2.1.4"
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file:
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dependency: transitive
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description:
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dependency: transitive
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description:
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name: js
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sha256: c1b2e9b5ea78c45e1a0788d29606ba27dc5f71f019f32ca5140f61ef071838cf
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sha256: f2c445dce49627136094980615a031419f7f3eb393237e4ecd97ac15dea343f3
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url: "https://pub.dev"
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source: hosted
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version: "0.7.1"
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version: "0.6.7"
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lints:
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dependency: transitive
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description:
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source: hosted
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version: "3.1.2"
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sdks:
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dart: ">=3.7.0-0 <4.0.0"
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dart: ">=3.7.0 <4.0.0"

‎lib/base64/base64.dart‎

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export 'converter/decoding.dart';
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export 'converter/encoding.dart';
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export 'exception/exception.dart';

‎lib/base64/converter/decoding.dart‎

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import 'package:blockchain_utils/base64/exception/exception.dart';
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import 'package:blockchain_utils/blockchain_utils.dart';
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class _Base64StreamDecoder {
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static const _base64Table =
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'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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static final _base64DecodeTable = () {
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final table = List<int>.filled(256, -1);
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for (int i = 0; i < _base64Table.length; i++) {
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table[_base64Table.codeUnitAt(i)] = i;
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}
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return table.immutable;
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}();
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static List<int> _decode(String encoded) {
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final cleaned = encoded.replaceAll('=', '');
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final output = <int>[];
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int i = 0;
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while (i + 4 <= cleaned.length) {
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int chunk = (_base64DecodeTable[cleaned.codeUnitAt(i)] << 18) |
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(_base64DecodeTable[cleaned.codeUnitAt(i + 1)] << 12) |
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(_base64DecodeTable[cleaned.codeUnitAt(i + 2)] << 6) |
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(_base64DecodeTable[cleaned.codeUnitAt(i + 3)]);
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output.add((chunk >> 16) & 0xFF);
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output.add((chunk >> 8) & 0xFF);
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output.add(chunk & 0xFF);
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i += 4;
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}
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int rem = cleaned.length - i;
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if (rem == 2) {
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int chunk = (_base64DecodeTable[cleaned.codeUnitAt(i)] << 18) |
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(_base64DecodeTable[cleaned.codeUnitAt(i + 1)] << 12);
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output.add((chunk >> 16) & 0xFF);
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} else if (rem == 3) {
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int chunk = (_base64DecodeTable[cleaned.codeUnitAt(i)] << 18) |
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(_base64DecodeTable[cleaned.codeUnitAt(i + 1)] << 12) |
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(_base64DecodeTable[cleaned.codeUnitAt(i + 2)] << 6);
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output.add((chunk >> 16) & 0xFF);
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output.add((chunk >> 8) & 0xFF);
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}
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return output;
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}
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final List<int> _output = [];
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String _carry = '';
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/// Adds Base64 string data to the decoder, buffering as needed.
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/// Strips out newline and carriage return characters.
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void add(String input) {
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_carry += input.replaceAll('\n', '').replaceAll('\r', '');
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while (_carry.length >= 4) {
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final chunk = _carry.substring(0, 4);
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_output.addAll(_decode(chunk));
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_carry = _carry.substring(4);
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}
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}
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/// Finalizes decoding by processing any remaining buffered data.
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/// Returns the full decoded byte list.
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List<int> finalize() {
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if (_carry.isNotEmpty) {
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_output.addAll(_decode(_carry.padRight(4, '=')));
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}
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return _output;
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}
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void clean() {
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_output.clear();
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_carry = '';
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}
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}
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/// A utility class for decoding Base64-encoded strings with options
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/// for URL-safe variant handling and padding validation.
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class B64Decoder {
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/// Decodes a Base64 [data] string into bytes.
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///
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/// [validatePadding]: If true (default), requires input length to be a multiple of 4.
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/// If false, padding '=' is added automatically to fix length.
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///
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/// [urlSafe]: If true (default), treats input as URL-safe Base64, converting
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/// '-' to '+' and '_' to '/' before decoding. If false, throws if URL-safe
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/// characters are present.
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///
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/// Throws [B64ConverterException] on invalid input or length.
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static List<int> decode(String data,
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{bool validatePadding = true, bool urlSafe = true}) {
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if (validatePadding && data.length % 4 != 0) {
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throw B64ConverterException("Invalid length, must be multiple of four");
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} else if (!validatePadding) {
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while (data.length % 4 != 0) {
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data += '=';
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}
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}
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if (urlSafe) {
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data = data.replaceAll('-', '+').replaceAll('_', '/');
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} else if (data.contains('-') || data.contains('_')) {
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throw B64ConverterException(
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'Invalid character in standard Base64 string: found URL-safe characters "-" or "_" but urlSafe is false.');
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}
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final encoder = _Base64StreamDecoder();
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try {
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encoder.add(data);
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return encoder.finalize().clone();
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} finally {
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encoder.clean();
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}
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}
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/// Tries to decode a Base64 string, returning null if decoding fails.
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///
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/// Same parameters as [decode], but catches exceptions and returns null on error.
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static List<int>? tryDecode(String data,
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{bool validatePadding = true, bool urlSafe = true}) {
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try {
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return decode(data, urlSafe: urlSafe, validatePadding: validatePadding);
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} catch (_) {
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return null;
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}
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}
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}

‎lib/base64/converter/encoding.dart‎

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import 'package:blockchain_utils/blockchain_utils.dart';
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/// A Base64 encoder that supports streaming data in chunks.
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/// It accumulates bytes and encodes them in groups of 3,
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/// handling padding for incomplete final blocks.
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class _Base64StreamEncoder {
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static const _base64Table =
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'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
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static String _encode(List<int> bytes) {
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final output = StringBuffer();
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int i = 0;
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while (i + 3 <= bytes.length) {
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int chunk = (bytes[i] << 16) | (bytes[i + 1] << 8) | (bytes[i + 2]);
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output.write(_base64Table[(chunk >> 18) & 0x3F]);
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output.write(_base64Table[(chunk >> 12) & 0x3F]);
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output.write(_base64Table[(chunk >> 6) & 0x3F]);
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output.write(_base64Table[chunk & 0x3F]);
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i += 3;
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}
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int remaining = bytes.length - i;
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if (remaining == 1) {
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int chunk = bytes[i] << 16;
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output.write(_base64Table[(chunk >> 18) & 0x3F]);
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output.write(_base64Table[(chunk >> 12) & 0x3F]);
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output.write('=');
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output.write('=');
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} else if (remaining == 2) {
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int chunk = (bytes[i] << 16) | (bytes[i + 1] << 8);
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output.write(_base64Table[(chunk >> 18) & 0x3F]);
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output.write(_base64Table[(chunk >> 12) & 0x3F]);
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output.write(_base64Table[(chunk >> 6) & 0x3F]);
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output.write('=');
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}
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return output.toString();
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}
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final StringBuffer _buffer = StringBuffer();
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final List<int> _partial = [];
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/// Adds bytes to the encoder buffer, encoding full 3-byte chunks immediately.
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void add(List<int> bytes) {
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_partial.addAll(bytes);
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while (_partial.length >= 3) {
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final chunk = _partial.sublist(0, 3);
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_buffer.write(_encode(chunk));
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_partial.removeRange(0, 3);
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}
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}
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/// Finalizes the encoding, encoding any remaining bytes with padding.
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/// Returns the full Base64 encoded string.
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String finalize() {
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if (_partial.isNotEmpty) {
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_buffer.write(_encode(_partial));
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}
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return _buffer.toString();
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}
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/// Clears internal buffers to reset the encoder state.
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void clean() {
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_buffer.clear();
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_partial.clear();
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}
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}
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/// Utility class for encoding bytes into Base64 strings with options for
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/// URL-safe encoding and optional padding removal.
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class B64Encoder {
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/// Encodes the given [data] bytes to a Base64 string.
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///
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/// [noPadding]: If true, removes the '=' padding characters from the output.
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/// Defaults to false (padding included).
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///
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/// [urlSafe]: If true, uses URL-safe Base64 encoding by replacing '+' with '-'
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/// and '/' with '_'. Defaults to false (standard Base64).
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///
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/// Returns the Base64-encoded string.
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static String encode(List<int> data,
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{bool noPadding = false, bool urlSafe = false}) {
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final encoder = _Base64StreamEncoder();
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try {
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encoder.add(data.asBytes);
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String b64 = encoder.finalize();
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if (urlSafe) {
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b64 = b64.replaceAll('+', '-').replaceAll('/', '_');
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}
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if (noPadding) {
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b64 = b64.replaceAll('=', '');
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}
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return b64;
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} finally {
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encoder.clean();
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}
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}
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}

‎lib/base64/exception/exception.dart‎

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import 'package:blockchain_utils/blockchain_utils.dart';
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class B64ConverterException extends BlockchainUtilsException {
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const B64ConverterException(super.message, {super.details});
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}

‎lib/crypto/crypto/crypto.dart‎

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export 'crc16/crc16.dart';
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export 'exception/exception.dart';
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export 'x25519/x25519.dart';
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export 'hkdf/hkdf.dart';
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export 'jwt/jwt.dart';

‎lib/crypto/crypto/hkdf/hkdf.dart‎

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import 'package:blockchain_utils/blockchain_utils.dart';
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/// A Dart implementation of the HKDF (HMAC-based Key Derivation Function) as defined in RFC 5869.
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/// This class supports both the extract and expand phases.
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class HKDF {
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/// Pseudorandom key (output of HKDF-Extract if enabled)
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final List<int> ork;
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/// Internal HMAC instance used for HKDF-Expand
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final HMAC _hmac;
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/// Desired length of output keying material (OKM)
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final int length;
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/// Optional context/application-specific information
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final List<int> info;
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HKDF._(
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{required List<int> ork,
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required HMAC hmac,
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List<int>? info,
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required this.length})
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: ork = ork.asImmutableBytes,
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info = (info ?? []).asImmutableBytes,
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_hmac = hmac;
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factory HKDF(
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{required List<int> ikm,
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required HashFunc hash,
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int length = 32,
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List<int>? salt,
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List<int>? info,
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bool hkdfExtract = true}) {
32+
final h = hash();
33+
int iteration = (length / h.getDigestLength).ceil();
34+
if (iteration > 255) {
35+
throw CryptoException('Cannot expand to more than 255 blocks');
36+
}
37+
if (hkdfExtract) {
38+
final ork = HMAC.hmac(hash, salt ?? List<int>.filled(32, 0), ikm);
39+
return HKDF._(
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ork: ork, info: info, hmac: HMAC(hash, ork), length: length);
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}
42+
return HKDF._(ork: ikm, hmac: HMAC(hash, ikm), info: info, length: length);
43+
}
44+
// HMAC-SHA256 helper
45+
List<int> _hash(List<int> data) {
46+
try {
47+
return _hmac.update(data).digest();
48+
} finally {
49+
_hmac.reset();
50+
}
51+
}
52+
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/// Derives the final output keying material (OKM) using HKDF-Expand
54+
List<int> derive({List<int> info = const []}) {
55+
int iteration = (length / _hmac.getDigestLength).ceil();
56+
List<int> okm = [];
57+
List<int> previousBlock = [];
58+
for (int i = 1; i <= iteration; i++) {
59+
final data = <int>[];
60+
data.addAll(previousBlock);
61+
data.addAll([...this.info, ...info]);
62+
data.add(i);
63+
previousBlock = _hash(data);
64+
okm.addAll(previousBlock);
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}
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return okm.sublist(0, length);
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}
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}

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