在 Dart 中将 ECPrivateKey/ECPublicKey 转换为 PEM 字符串

Question

我有一个 ECPrivateKey/ECPublicKey，想将其转换为如下 PEM 字符串

公钥：

-----BEGIN PUBLIC KEY----- MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEnd21ku0m+VZvM3tJAP3IIM3XXGla PM2zhRura+/qioJoUwDK7qLbuFzcmbHHx6ELnXFXgAjDbZgFyMdfcm1ugw== -----END PUBLIC KEY-----

私钥：

-----BEGIN PRIVATE KEY----- MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg2sfmpsl894GDcNOl vzKW0gzf/b8XvQigr/rZGSjKydqhRANCAASd3bWS7Sb5Vm8ze0kA/cggzddcaVo8 zbOFG6tr7+qKgmhTAMruotu4XNyZscfHoQudcVeACMNtmAXIx19ybW6D -----END PRIVATE KEY-----

Answer 1

如果你喂

MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEnd21ku0m+VZvM3tJAP3IIM3XXGla PM2zhRura+/qioJoUwDK7qLbuFzcmbHHx6ELnXFXgAjDbZgFyMdfcm1ugw==

进入像this 这样的ASN.1 解析器，您会发现它只是一些oid（包括曲线）和密钥的R/S 值的Base64/ASN.1 编码。该编码在 PKCS#8 规范中有所描述。

SEQUENCE (2 elem)   SEQUENCE (2 elem)
    OBJECT IDENTIFIER 1.2.840.10045.2.1 ecPublicKey (ANSI X9.62 public key type)
    OBJECT IDENTIFIER 1.2.840.10045.3.1.7 prime256v1 (ANSI X9.62 named elliptic curve)
    BIT STRING (520 bit) 0000010010011101110111011011010110010010111011010010011011111001010101…

使用Dart ASN encoder/decoder package 首先解码上面的示例，以探索 ASN 组件的顺序和嵌套。然后反转该过程并使用库的编码器部分对其进行重新编码，并断言您将获得与开始时相同的 BER 编码。现在您可以对任何您喜欢的密钥进行编码。

Answer 2

查看 Dart Basic Utils 包。我通过使用 Pointycastle 和 ASN1 包完成了这项工作。

更新 pubspec.yaml 并将以下行添加到您的依赖项中。

dependencies:
  basic_utils: ^2.5.6

存储库：https://github.com/Ephenodrom/Dart-Basic-Utils

Pub.dev：https://pub.dev/packages/basic_utils

String encodeEcPublicKeyToPem(ECPublicKey publicKey);
String encodeEcPrivateKeyToPem(ECPrivateKey ecPrivateKey);

如果你不想使用包，这里是完整的代码：

static String encodeEcPublicKeyToPem(ECPublicKey publicKey) {
    ASN1ObjectIdentifier.registerFrequentNames();
    var outer = ASN1Sequence();
    var algorithm = ASN1Sequence();
    algorithm.add(ASN1ObjectIdentifier.fromName('ecPublicKey'));
    algorithm.add(ASN1ObjectIdentifier.fromName('prime256v1'));
    var subjectPublicKey = ASN1BitString(publicKey.Q.getEncoded(false));

    outer.add(algorithm);
    outer.add(subjectPublicKey);
    var dataBase64 = base64.encode(outer.encodedBytes);
    var chunks = StringUtils.chunk(dataBase64, 64);

    return '$BEGIN_EC_PUBLIC_KEY\n${chunks.join('\n')}\n$END_EC_PUBLIC_KEY';
  }

static String encodeEcPrivateKeyToPem(ECPrivateKey ecPrivateKey) {
    ASN1ObjectIdentifier.registerFrequentNames();
    var outer = ASN1Sequence();

    var version = ASN1Integer(BigInt.from(1));
    var privateKeyAsBytes = _bigIntToBytes(ecPrivateKey.d);
    var privateKey = ASN1OctetString(privateKeyAsBytes);
    var choice = ASN1Sequence(tag: 0xA0);

    choice
        .add(ASN1ObjectIdentifier.fromName(ecPrivateKey.parameters.domainName));

    var publicKey = ASN1Sequence(tag: 0xA1);

    var subjectPublicKey =
        ASN1BitString(ecPrivateKey.parameters.G.getEncoded(false));
    publicKey.add(subjectPublicKey);

    outer.add(version);
    outer.add(privateKey);
    outer.add(choice);
    outer.add(publicKey);
    var dataBase64 = base64.encode(outer.encodedBytes);
    var chunks = StringUtils.chunk(dataBase64, 64);

    return '$BEGIN_EC_PRIVATE_KEY\n${chunks.join('\n')}\n$END_EC_PRIVATE_KEY';
  }