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Bouncycastle OpenPGP：如何创建具有两个用户ID的PGP密钥对？

javabouncycastleopenpgp
4

使用命令行 gnupg，我可以创建一个包含 RSA 密钥的密钥环，针对 "John Doe <john@doe.com>" 的用户。我还可以使用 --edit-key 和 adduid 来添加另一个用户名为 "Jane Doe <jane@doe.com>" 的用户。生成的 secring.gpg 文件看起来像这样：

$ gpg -vv secring.gpg
:secret key packet:
        version 4, algo 1, created 1380898817, expires 0
        skey[0]: [2048 bits]
        skey[1]: [17 bits]
        iter+salt S2K, algo: 9, SHA1 protection, hash: 2, salt: 3825c4409323d7b0
        protect count: 65536 (96)
        protect IV:  ac f9 8d 4a b7 3a 5d 7c b2 3c 28 ff 82 6d 4c ef
        encrypted stuff follows
:user ID packet: "John Doe <john@doe.com>"
:signature packet: algo 1, keyid 9991E2282A9906C7
        version 4, created 1380898818, md5len 0, sigclass 0x13
        digest algo 2, begin of digest bd 01
        hashed subpkt 2 len 4 (sig created 2013-10-04)
        hashed subpkt 27 len 1 (key flags: 03)
        hashed subpkt 11 len 5 (pref-sym-algos: 9 8 7 3 2)
        hashed subpkt 21 len 5 (pref-hash-algos: 8 2 9 10 11)
        hashed subpkt 22 len 3 (pref-zip-algos: 2 3 1)
        hashed subpkt 30 len 1 (features: 01)
        subpkt 16 len 8 (issuer key ID 9991E2282A9906C7)
        data: [2045 bits]
:trust packet: flag=00 sigcache=00
:user ID packet: "Jane Doe <jane@doe.com>"
:signature packet: algo 1, keyid 9991E2282A9906C7
        version 4, created 1380899570, md5len 0, sigclass 0x13
        digest algo 2, begin of digest 2f 50
        hashed subpkt 2 len 4 (sig created 2013-10-04)
        hashed subpkt 27 len 1 (key flags: 03)
        hashed subpkt 11 len 5 (pref-sym-algos: 9 8 7 3 2)
        hashed subpkt 21 len 5 (pref-hash-algos: 8 2 9 10 11)
        hashed subpkt 22 len 3 (pref-zip-algos: 2 3 1)
        hashed subpkt 30 len 1 (features: 01)
        hashed subpkt 23 len 1 (key server preferences: 80)
        subpkt 16 len 8 (issuer key ID 9991E2282A9906C7)
        data: [2047 bits]
:trust packet: flag=00 sigcache=00
sec  2048R/2A9906C7 2013-10-04 John Doe <john@doe.com>
sig        2A9906C7 2013-10-04   [selfsig]
uid                            Jane Doe <jane@doe.com>
sig        2A9906C7 2013-10-04   [selfsig]

我希望使用Bouncycastle在Java中创建与以下签名相同的内容，即从java.security.KeyPair开始：

public void createKeyRing(KeyPair keyPair, char[] pass, String[] ids)

在这段代码中，pass是密码，ids = new String[] {"John Doe <john@doe.com>", "Jane Doe <jane@doe.com>"}。我按照这个教程的指引进行操作，其中关键的代码部分如下：

PGPKeyRingGenerator keyRingGen =
    new PGPKeyRingGenerator(
        PGPSignature.POSITIVE_CERTIFICATION, rsakp_sign,
        id, sha1Calc, signhashgen.generate(), null,
        new BcPGPContentSignerBuilder(
            rsakp_sign.getPublicKey().getAlgorithm(),
            HashAlgorithmTags.SHA1),
        pske);

// Add our encryption subkey, together with its signature.
keyRingGen.addSubKey(rsakp_enc, enchashgen.generate(), null);

其中，rsakp_sign和rsakp_enc分别是签名和加密密钥的RSA密钥对，signhashgen和enchashgen是包含算法偏好等子数据包的生成器。

只要我只为John创建一个密钥，一切都很好。但当我想添加Jane时，就遇到了问题：显然我不能使用addSubKey为Jane添加一个经过signhashgen处理的密钥对。第一个天真的尝试如下：

PGPSignatureGenerator sGen = new PGPSignatureGenerator(
  new BcPGPContentSignerBuilder(PGPPublicKey.RSA_SIGN, PGPUtil.SHA1));
sGen.init(PGPSignature.POSITIVE_CERTIFICATION, pgpPrivateKey);
PGPSignature certification = sGen.generateCertification("Jane Doe <jane@doe.com>", pgpPublicKey);

PGPPublicKey newKey = PGPPublicKey.addCertification(pgpPublicKey, "Jane Doe <jane@doe.com>", certification);

keyRingGen.addSubKey(new PGPKeyPair(newKey, pgpPrivateKey), enchashgen.generate(), null);

而这样做将没有任何作用，gpg --vv meeththedoes.asc 中不会出现任何额外的条目。

或者，我可以使用 John 的密钥环，提取私钥，然后添加 Jane：

PGPSecretKeyRing keyRing = keyRingGen.generateSecretKeyRing();

PGPSecretKey pgpSecretKey = keyRing.getSecretKey();
BcPGPDigestCalculatorProvider calculatorProvider = new BcPGPDigestCalculatorProvider();
BcPBESecretKeyDecryptorBuilder decryptor = new BcPBESecretKeyDecryptorBuilder(calculatorProvider);
PGPPrivateKey pgpPrivateKey = pgpSecretKey.extractPrivateKey(decryptor.build(pass));    
PGPPublicKey pgpPublicKey = pgpSecretKey.getPublicKey();

PGPSignatureGenerator    sGen = new PGPSignatureGenerator(
  new BcPGPContentSignerBuilder(PGPPublicKey.RSA_SIGN, PGPUtil.SHA1));
sGen.init(PGPSignature.POSITIVE_CERTIFICATION, pgpPrivateKey);
PGPSignature certification = sGen.generateCertification("Jane Doe <jane@doe.com>", pgpPublicKey);

PGPPublicKey newKey = PGPPublicKey.addCertification(pgpPublicKey, "Jane Doe <jane@doe.com>", certification);

pgpSecretKey = PGPSecretKey.replacePublicKey(pgpSecretKey, newKey);

这个方法有点可行，但是在生成的密钥环中，John和Jane拥有不同的子数据包集合：

$ gpg -vv meetthedoes.asc
gpg: ASCII-Hülle: BEGIN PGP PRIVATE KEY BLOCK
gpg: ASCII-Hülle: Version: BCPG v1.48
:secret key packet:
        version 4, algo 3, created 1380908986, expires 0
        skey[0]: [2048 bits]
        skey[1]: [17 bits]
        iter+salt S2K, algo: 9, SHA1 protection, hash: 2, salt: 696d2d42bd6b727c
        protect count: 65536 (96)
        protect IV:  87 31 81 df 17 fa 74 c4 c3 35 39 26 98 c1 15 27
        encrypted stuff follows
:user ID packet: "John Doe <john@doe.com>"
:signature packet: algo 3, keyid 3A80073198CF2010
        version 4, created 1380908986, md5len 0, sigclass 0x13
        digest algo 2, begin of digest a5 c8
        hashed subpkt 2 len 4 (sig created 2013-10-04)
        hashed subpkt 27 len 1 (key flags: 03)
        hashed subpkt 11 len 5 (pref-sym-algos: 9 8 7 3 2)
        hashed subpkt 21 len 5 (pref-hash-algos: 8 2 9 10 11)
        hashed subpkt 22 len 3 (pref-zip-algos: 2 3 1)
        hashed subpkt 30 len 1 (features: 01)
        subpkt 16 len 8 (issuer key ID 3A80073198CF2010)
        data: [2047 bits]
:user ID packet: "Jane Doe <jane@doe.com>"
:signature packet: algo 3, keyid 3A80073198CF2010
        version 4, created 1380908986, md5len 0, sigclass 0x13
        digest algo 2, begin of digest f6 e8
        hashed subpkt 2 len 4 (sig created 2013-10-04)
        subpkt 16 len 8 (issuer key ID 3A80073198CF2010)
        data: [2039 bits]
sec  2048s/98CF2010 2013-10-04 John Doe <john@doe.com>
sig        98CF2010 2013-10-04   [selfsig]
uid                            Jane Doe <jane@doe.com>
sig        98CF2010 2013-10-04   [selfsig]

我想您可能不需要这个，对吧？无论如何，这种方法似乎也是错误的。我应该先完全操纵生成器，然后让Bouncycastle一次性地生成密钥环文件，对吗？我在这里做错了什么吗？

1个回答
4
API在添加第一个UID和后续UID之间似乎有所不同。对于John，我可以说：
PGPKeyRingGenerator generator = new PGPKeyRingGenerator(
  PGPSignature.POSITIVE_CERTIFICATION, 
  signKeyPair, john, sha1Calc,
  signhashgen.generate(), null,
  new BcPGPContentSignerBuilder(
    signKeyPair.getPublicKey().getAlgorithm(),
    HashAlgorithmTags.SHA1),
    new BcPBESecretKeyEncryptorBuilder(PGPEncryptedData.AES_256).build(pass)
);    
generator.addSubKey(encKeyPair, enchashgen.generate(), null);    
PGPSecretKeyRing ring = generator.generateSecretKeyRing();

这段内容涉及到IT技术，讲的是如何创建带有签名密钥和加密子密钥的秘钥环，类似于gnupgp的做法。但是对于Jane来说，这种方法不可行，因为包含有关她子密钥信息的signhashgen不是addSubKey的参数。相反，我可以从环中提取John的秘钥，创建一个PGPPrivateKey，并使用它来签署Jane的uid。

PGPSignatureGenerator generator = new PGPSignatureGenerator(new BcPGPContentSignerBuilder(PGPPublicKey.RSA_GENERAL,
  PGPUtil.SHA1)); 
generator.init(PGPSignature.POSITIVE_CERTIFICATION, johnsPrivateKey);
PGPSignatureSubpacketGenerator signhashgen = copyJohnsSignhashgen();      
generator.setHashedSubpackets(signhashgen.generate());    
PGPSignature certification = generator.generateCertification(jane, getEncryptionKey(secretKeyRing));
PGPPublicKey janesKey = PGPPublicKey.addCertification(getEncryptionKey(secretKeyRing), jane, certification);

所有需要做的就是将新密钥添加到密钥环中。
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