tovi
/
Envelope


								import 'dart:convert';

								import 'dart:math';

								import 'dart:typed_data';

								import "package:pointycastle/export.dart";

								import "package:asn1lib/asn1lib.dart";


								/*

								var rsaKeyHelper = RsaKeyHelper();

								var keyPair = rsaKeyHelper.generateRSAkeyPair();

								var rsaPub = keyPair.publicKey;

								var rsaPriv = keyPair.privateKey;

								var cipherText = rsaKeyHelper.rsaEncrypt(rsaPub, Uint8List.fromList('Test Data'.codeUnits));

								print(cipherText);

								var plainText = rsaKeyHelper.rsaDecrypt(rsaPriv, cipherText);

								print(String.fromCharCodes(plainText));

								 */


								List<int> decodePEM(String pem) {

								    var startsWith = [

								        '-----BEGIN PUBLIC KEY-----',

								        '-----BEGIN PUBLIC KEY-----',

								        '\n-----BEGIN PUBLIC KEY-----',

								        '-----BEGIN PRIVATE KEY-----',

								        '-----BEGIN PGP PUBLIC KEY BLOCK-----\r\nVersion: React-Native-OpenPGP.js 0.1\r\nComment: http://openpgpjs.org\r\n\r\n',

								        '-----BEGIN PGP PRIVATE KEY BLOCK-----\r\nVersion: React-Native-OpenPGP.js 0.1\r\nComment: http://openpgpjs.org\r\n\r\n',

								    ];

								    var endsWith = [

								        '-----END PUBLIC KEY-----',

								        '-----END PRIVATE KEY-----',

								        '-----END PGP PUBLIC KEY BLOCK-----',

								        '-----END PGP PRIVATE KEY BLOCK-----',

								    ];

								    bool isOpenPgp = pem.contains('BEGIN PGP');


								    for (var s in startsWith) {

								        if (pem.startsWith(s)) {

								            pem = pem.substring(s.length);

								        }

								    }


								    for (var s in endsWith) {

								        if (pem.endsWith(s)) {

								            pem = pem.substring(0, pem.length - s.length);

								        }

								    }


								    if (isOpenPgp) {

								        var index = pem.indexOf('\r\n');

								        pem = pem.substring(0, index);

								    }


								    pem = pem.replaceAll('\n', '');

								    pem = pem.replaceAll('\r', '');


								    return base64.decode(pem);

								}


								class RsaKeyHelper {


								    // Generate secure random sequence for seed

								    SecureRandom secureRandom() {

								        var secureRandom = FortunaRandom();

								        var random = Random.secure();

								        List<int> seeds = [];

								        for (int i = 0; i < 32; i++) {

								            seeds.add(random.nextInt(255));

								        }

								        secureRandom.seed(KeyParameter(Uint8List.fromList(seeds)));


								        return secureRandom;

								    }


								    // Generate RSA key pair

								    AsymmetricKeyPair<RSAPublicKey, RSAPrivateKey> generateRSAkeyPair({int bitLength = 2048}) {

								        var secureRandom = this.secureRandom();


								        // final keyGen = KeyGenerator('RSA'); // Get using registry

								        final keyGen = RSAKeyGenerator();


								        keyGen.init(ParametersWithRandom(

								                        RSAKeyGeneratorParameters(BigInt.parse('65537'), bitLength, 64),

								                        secureRandom));


								        // Use the generator


								        final pair = keyGen.generateKeyPair();


								        // Cast the generated key pair into the RSA key types


								        final myPublic = pair.publicKey as RSAPublicKey;

								        final myPrivate = pair.privateKey as RSAPrivateKey;


								        return AsymmetricKeyPair<RSAPublicKey, RSAPrivateKey>(myPublic, myPrivate);

								    }


								    // Encrypt data using RSA key

								    Uint8List rsaEncrypt(RSAPublicKey myPublic, Uint8List dataToEncrypt) {

								        final encryptor = OAEPEncoding(RSAEngine())

								                ..init(true, PublicKeyParameter<RSAPublicKey>(myPublic)); // true=encrypt


								        return _processInBlocks(encryptor, dataToEncrypt);

								    }


								    // Decrypt data using RSA key

								    Uint8List rsaDecrypt(RSAPrivateKey myPrivate, Uint8List cipherText) {

								        final decryptor = OAEPEncoding(RSAEngine())

								                ..init(false, PrivateKeyParameter<RSAPrivateKey>(myPrivate)); // false=decrypt


								        return _processInBlocks(decryptor, cipherText);

								    }


								    // Process blocks after encryption/descryption

								    Uint8List _processInBlocks(AsymmetricBlockCipher engine, Uint8List input) {

								        final numBlocks = input.length ~/ engine.inputBlockSize +

								                ((input.length % engine.inputBlockSize != 0) ? 1 : 0);


								        final output = Uint8List(numBlocks * engine.outputBlockSize);


								        var inputOffset = 0;

								        var outputOffset = 0;

								        while (inputOffset < input.length) {

								            final chunkSize = (inputOffset + engine.inputBlockSize <= input.length)

								                    ? engine.inputBlockSize

								                    : input.length - inputOffset;


								            outputOffset += engine.processBlock(

								                    input, inputOffset, chunkSize, output, outputOffset);


								            inputOffset += chunkSize;

								        }


								        return (output.length == outputOffset)

								                ? output

								                : output.sublist(0, outputOffset);

								    }


								    // Encode RSA public key to pem format

								    static encodePublicKeyToPem(RSAPublicKey publicKey) {

								        var algorithmSeq = ASN1Sequence();

								        var algorithmAsn1Obj = ASN1Object.fromBytes(Uint8List.fromList([0x6, 0x9, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0xd, 0x1, 0x1, 0x1]));

								        var paramsAsn1Obj = ASN1Object.fromBytes(Uint8List.fromList([0x5, 0x0]));

								        algorithmSeq.add(algorithmAsn1Obj);

								        algorithmSeq.add(paramsAsn1Obj);


								        var publicKeySeq = ASN1Sequence();

								        publicKeySeq.add(ASN1Integer(publicKey.modulus!));

								        publicKeySeq.add(ASN1Integer(publicKey.exponent!));

								        var publicKeySeqBitString = ASN1BitString(Uint8List.fromList(publicKeySeq.encodedBytes));


								        var topLevelSeq = ASN1Sequence();

								        topLevelSeq.add(algorithmSeq);

								        topLevelSeq.add(publicKeySeqBitString);

								        var dataBase64 = base64.encode(topLevelSeq.encodedBytes);


								        return """-----BEGIN PUBLIC KEY-----\r\n$dataBase64\r\n-----END PUBLIC KEY-----""";

								    }


								    // Parse public key PEM file

								    static parsePublicKeyFromPem(pemString) {

								        List<int> publicKeyDER = decodePEM(pemString);

								        var asn1Parser = ASN1Parser(Uint8List.fromList(publicKeyDER));

								        var topLevelSeq = asn1Parser.nextObject() as ASN1Sequence;

								        var publicKeyBitString = topLevelSeq.elements[1];


								        var publicKeyAsn = ASN1Parser(publicKeyBitString.contentBytes()!, relaxedParsing: true);

								        var publicKeySeq = publicKeyAsn.nextObject() as ASN1Sequence;

								        var modulus = publicKeySeq.elements[0] as ASN1Integer;

								        var exponent = publicKeySeq.elements[1] as ASN1Integer;


								        RSAPublicKey rsaPublicKey = RSAPublicKey(

								                modulus.valueAsBigInteger!,

								                exponent.valueAsBigInteger!

								        );


								        return rsaPublicKey;

								    }


								    // Encode RSA private key to pem format

								    static encodePrivateKeyToPem(RSAPrivateKey privateKey) {

								        var version = ASN1Integer(BigInt.zero);


								        var algorithmSeq = ASN1Sequence();

								        var algorithmAsn1Obj = ASN1Object.fromBytes(Uint8List.fromList([

								            0x6, 0x9, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0xd, 0x1, 0x1, 0x1

								        ]));

								        var paramsAsn1Obj = ASN1Object.fromBytes(Uint8List.fromList([0x5, 0x0]));

								        algorithmSeq.add(algorithmAsn1Obj);

								        algorithmSeq.add(paramsAsn1Obj);


								        var privateKeySeq = ASN1Sequence();

								        var modulus = ASN1Integer(privateKey.n!);

								        var publicExponent = ASN1Integer(BigInt.parse('65537'));

								        var privateExponent = ASN1Integer(privateKey.privateExponent!);

								        var p = ASN1Integer(privateKey.p!);

								        var q = ASN1Integer(privateKey.q!);

								        var dP = privateKey.privateExponent! % (privateKey.p! - BigInt.one);

								        var exp1 = ASN1Integer(dP);

								        var dQ = privateKey.privateExponent! % (privateKey.q! - BigInt.one);

								        var exp2 = ASN1Integer(dQ);

								        var iQ = privateKey.q?.modInverse(privateKey.p!);

								        var co = ASN1Integer(iQ!);


								        privateKeySeq.add(version);

								        privateKeySeq.add(modulus);

								        privateKeySeq.add(publicExponent);

								        privateKeySeq.add(privateExponent);

								        privateKeySeq.add(p);

								        privateKeySeq.add(q);

								        privateKeySeq.add(exp1);

								        privateKeySeq.add(exp2);

								        privateKeySeq.add(co);

								        var publicKeySeqOctetString = ASN1OctetString(Uint8List.fromList(privateKeySeq.encodedBytes));


								        var topLevelSeq = ASN1Sequence();

								        topLevelSeq.add(version);

								        topLevelSeq.add(algorithmSeq);

								        topLevelSeq.add(publicKeySeqOctetString);

								        var dataBase64 = base64.encode(topLevelSeq.encodedBytes);


								        return """-----BEGIN PRIVATE KEY-----\r\n$dataBase64\r\n-----END PRIVATE KEY-----""";

								    }


								    static parsePrivateKeyFromPem(pemString) {

								        List<int> privateKeyDER = decodePEM(pemString);

								        var asn1Parser = ASN1Parser(Uint8List.fromList(privateKeyDER));

								        var topLevelSeq = asn1Parser.nextObject() as ASN1Sequence;

								        var version = topLevelSeq.elements[0];

								        var algorithm = topLevelSeq.elements[1];

								        var privateKey = topLevelSeq.elements[2];


								        asn1Parser = ASN1Parser(privateKey.contentBytes()!);

								        var pkSeq = asn1Parser.nextObject() as ASN1Sequence;


								        version = pkSeq.elements[0];

								        var modulus = pkSeq.elements[1] as ASN1Integer;

								        //var publicExponent = pkSeq.elements[2] as ASN1Integer;

								        var privateExponent = pkSeq.elements[3] as ASN1Integer;

								        var p = pkSeq.elements[4] as ASN1Integer;

								        var q = pkSeq.elements[5] as ASN1Integer;

								        var exp1 = pkSeq.elements[6] as ASN1Integer;

								        var exp2 = pkSeq.elements[7] as ASN1Integer;

								        var co = pkSeq.elements[8] as ASN1Integer;


								        RSAPrivateKey rsaPrivateKey = RSAPrivateKey(

								                modulus.valueAsBigInteger!,

								                privateExponent.valueAsBigInteger!,

								                p.valueAsBigInteger,

								                q.valueAsBigInteger

								        );


								        return rsaPrivateKey;

								    }

								}