使用BouncyCastle解析EdDSA类型PGP公钥时指纹异常且UserID为空

问题描述 #

使用BouncyCastle解析PGP公钥时，RSA加密生成的公钥可正常读取信息，但EdDSA生成的公钥出现异常：获取到的指纹与Kleopatra显示的不一致，且UserIDs为空。

依赖与测试代码 #

依赖配置 #

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk18on</artifactId>
    <version>1.72</version>
</dependency>

测试代码 #

@Test
public void test() throws NoSuchProviderException, IOException, PGPException {
    InputStream in = PGPUtil.getDecoderStream(new FileInputStream("public_EdDsa.asc"));

    PGPPublicKeyRingCollection pgpPub = new PGPPublicKeyRingCollection(in, new JcaKeyFingerprintCalculator());

    List<PGPPublicKey> keys = new ArrayList<>();

    Iterator<PGPPublicKeyRing> rIt = pgpPub.getKeyRings();

    while (CollectionUtils.isEmpty(keys) && rIt.hasNext()) {
        PGPPublicKeyRing kRing = rIt.next();
        Iterator<PGPPublicKey> kIt = kRing.getPublicKeys();
        while (CollectionUtils.isEmpty(keys) && kIt.hasNext()) {
            PGPPublicKey k = kIt.next();
            if (k.isEncryptionKey()) {
                keys.add(k);
            }
        }
    }

    for (PGPPublicKey pgpPublicKey : keys) {
        System.out.println(pgpPublicKey.getKeyID());

        byte[] fingerprint = pgpPublicKey.getFingerprint();
        for (byte b : fingerprint) {
            System.out.print(b);
        }
        System.out.println();
        System.out.println(byte2Hex(fingerprint));

        Iterator<String> userIDs = pgpPublicKey.getUserIDs();
        while (userIDs.hasNext()){
            String next = userIDs.next();
            System.out.println(next);
        }

        System.out.println("============end============");
    }
}

解决方案 #

1. 升级BouncyCastle版本 #

BouncyCastle 1.72对EdDSA的PGP支持存在缺陷，建议升级到1.73及以上稳定版本（如1.77），后续版本修复了EdDSA密钥的解析问题，能正确读取指纹和关联信息。

修改依赖：

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk18on</artifactId>
    <version>1.77</version>
</dependency>

2. 修正密钥筛选逻辑 #

EdDSA在PGP体系中默认作为签名密钥使用，而非加密密钥。原代码仅筛选isEncryptionKey()的密钥，会漏掉EdDSA主密钥，导致读取到的是无关子密钥（或无密钥），进而出现指纹不匹配、UserIDs为空的问题。

修改筛选条件，同时包含签名密钥：

// 替换原有的if判断
if (k.isEncryptionKey() || k.isSigningKey()) {
    keys.add(k);
}

另外，原代码中CollectionUtils.isEmpty(keys) && ...的逻辑会在找到第一个符合条件的密钥后停止遍历，建议去掉该限制，遍历所有密钥以确认主密钥信息。

3. 修复指纹显示逻辑 #

直接打印byte数组的原始值会因byte的有符号特性导致显示异常，需确保byte2Hex方法将byte作为无符号值转换为十六进制：

private static String byte2Hex(byte[] bytes) {
    StringBuilder sb = new StringBuilder();
    for (byte b : bytes) {
        sb.append(String.format("%02X", b & 0xFF));
    }
    return sb.toString();
}

修改后的完整测试代码 #

@Test
public void test() throws NoSuchProviderException, IOException, PGPException {
    InputStream in = PGPUtil.getDecoderStream(new FileInputStream("public_EdDsa.asc"));

    PGPPublicKeyRingCollection pgpPub = new PGPPublicKeyRingCollection(in, new JcaKeyFingerprintCalculator());

    List<PGPPublicKey> keys = new ArrayList<>();

    Iterator<PGPPublicKeyRing> rIt = pgpPub.getKeyRings();

    while (rIt.hasNext()) {
        PGPPublicKeyRing kRing = rIt.next();
        Iterator<PGPPublicKey> kIt = kRing.getPublicKeys();
        while (kIt.hasNext()) {
            PGPPublicKey k = kIt.next();
            if (k.isEncryptionKey() || k.isSigningKey()) {
                keys.add(k);
            }
        }
    }

    for (PGPPublicKey pgpPublicKey : keys) {
        System.out.println("密钥ID: " + Long.toHexString(pgpPublicKey.getKeyID()).toUpperCase());

        byte[] fingerprint = pgpPublicKey.getFingerprint();
        System.out.println("指纹十六进制: " + byte2Hex(fingerprint));

        Iterator<String> userIDs = pgpPublicKey.getUserIDs();
        while (userIDs.hasNext()){
            String next = userIDs.next();
            System.out.println("用户ID: " + next);
        }

        System.out.println("密钥用途: " + (pgpPublicKey.isSigningKey() ? "签名" : "") 
                + (pgpPublicKey.isEncryptionKey() ? "加密" : ""));
        System.out.println("============end============");
    }
}

private static String byte2Hex(byte[] bytes) {
    StringBuilder sb = new StringBuilder();
    for (byte b : bytes) {
        sb.append(String.format("%02X", b & 0xFF));
    }
    return sb.toString();
}

内容的提问来源于stack exchange，提问作者Lei