150 lines
3.6 KiB
Dart
Executable File
150 lines
3.6 KiB
Dart
Executable File
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class _ASN1Object {
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_ASN1Object() {
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tlv = null;
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}
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String? tlv;
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String t = '00';
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String l = '00';
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String v = '';
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/// 获取 der 编码比特流16进制串
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String getEncodedHex() {
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if (tlv == null) {
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v = getValue();
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l = getLength();
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tlv = t + l + v;
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}
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return tlv!;
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}
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String getLength() {
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int n = v.length ~/ 2; // 字节数
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String nHex = n.toRadixString(16);
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if (nHex.length % 2 == 1) nHex = '0$nHex';
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if (n < 128) {
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return nHex;
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} else {
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int head = 128 + nHex.length ~/ 2;
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return head.toRadixString(16) + nHex;
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}
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}
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String getValue() {
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return '';
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}
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}
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class _DERInteger extends _ASN1Object {
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_DERInteger(BigInt? bigint) : super() {
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t = '02'; // 整型标签说明
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if (bigint != null) v = bigintToValue(bigint);
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}
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@override
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String getValue() {
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return v;
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}
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String bigintToValue(BigInt inputBigInt) {
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String hexString = inputBigInt.toRadixString(16);
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if (!hexString.startsWith('-')) {
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if (hexString.length % 2 == 1) {
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hexString = '0$hexString';
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} else if (!RegExp(r'^[0-7]').hasMatch(hexString)) {
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hexString = '00$hexString';
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}
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} else {
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// Negative number
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hexString = hexString.substring(1);
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int paddedLength = hexString.length;
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if (paddedLength % 2 == 1) {
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paddedLength += 1; // Pad to a whole byte
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} else if (!RegExp(r'^[0-7]').hasMatch(hexString)) {
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paddedLength += 2;
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}
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String bitmask = '';
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for (int i = 0; i < paddedLength; i++) {
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bitmask += 'f';
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}
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BigInt bitmaskBigInt = BigInt.parse(bitmask, radix: 16);
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BigInt twosComplementBigInt = bitmaskBigInt ^ inputBigInt;
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twosComplementBigInt = twosComplementBigInt + BigInt.one;
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hexString = twosComplementBigInt.toRadixString(16).replaceAll(RegExp(r'^-'), '');
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}
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return hexString;
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}
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}
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class _DERSequence extends _ASN1Object {
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_DERSequence(this.asn1Array) : super() {
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t = '30'; // 序列标签说明
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}
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List<_ASN1Object> asn1Array;
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@override
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String getValue() {
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v = asn1Array.map((asn1Object) => asn1Object.getEncodedHex()).join('');
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return v;
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}
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}
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int getLenOfL(String str, int start) {
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if (int.parse(str[start + 2]) < 8) return 1;
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return int.parse(str.substring(start + 2, start + 4)) & 0x7f + 1;
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}
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int getL(String str, int start) {
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// 获取 l
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int len = getLenOfL(str, start);
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String l = str.substring(start + 2, start + 2 + len * 2);
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if (l.isEmpty) return -1;
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BigInt bigint = int.parse(l[0]) < 8
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? BigInt.parse(l, radix: 16)
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: BigInt.parse(l.substring(2), radix: 16);
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return bigint.toInt();
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}
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int getStartOfV(String str, int start) {
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int len = getLenOfL(str, start);
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return start + (len + 1) * 2;
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}
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class ASN1Utils {
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/// ASN.1 der 编码，针对 sm2 签名
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static String encodeDer(BigInt r, BigInt s) {
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final derR = _DERInteger(r);
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final derS = _DERInteger(s);
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final derSeq = _DERSequence([derR, derS]);
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return derSeq.getEncodedHex();
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}
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/// 解析 ASN.1 der，针对 sm2 验签
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static Map<String, BigInt> decodeDer(String input) {
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int start = getStartOfV(input, 0);
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int vIndexR = getStartOfV(input, start);
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int lR = getL(input, start);
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String vR = input.substring(vIndexR, vIndexR + lR * 2);
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int nextStart = vIndexR + vR.length;
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int vIndexS = getStartOfV(input, nextStart);
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int lS = getL(input, nextStart);
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String vS = input.substring(vIndexS, vIndexS + lS * 2);
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BigInt r = BigInt.parse(vR, radix: 16);
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BigInt s = BigInt.parse(vS, radix: 16);
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return {'r': r, 's': s};
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}
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} |