OpenSSL 的 rsautl 无法加载使用 PEM_write_RSAPublicKey 创建的公钥

2022-01-07 00:00:00 openssl c++ pem

我使用 openssl 生成了一个公钥

BIGNUM* e = BN_new();BN_set_word(e, 17);RSA* rsa = RSA_new();如果(!RSA_generate_key_ex(rsa,2048,e,NULL)){日志(安全,调试)<<生成私钥失败";}

这些被写入文件:

FILE* pubwriter = fopen("key.pub", "wb");int err = PEM_write_RSAPublicKey(pubwriter, key);如果(!错误){throw new std::runtime_error("无法存储公钥");}FILE* privwriter = fopen("key.priv", "wb");std::string 密码 = "密码";err = PEM_write_RSAPrivateKey(privwriter, key, EVP_des_ede3_cbc(),(unsigned char*)password.c_str(),密码.size(), NULL, NULL);

而且它们似乎存储正确,key.pub 然后包含类似

-----BEGIN RSA 公钥-----MIIBCAKCAQEA0rG1b0g3NIsDT8HkzgTx8BUI9LhueWbH1NuAvIh9qTF57GzEXuTujxBcuSzWXlR83ci4oITp7VqV6KLVoJryf8orGXBVi9A73JYOQVB6FEzARKym/g8EfSEwSmdQ4NfiTESwOCtIextdu3x8pANSYDyyqdiWsSHy0SiZmkbvdVYomIBJZOV9jhb3mkmD0WUYie9AXziTbli97YqDiN168kMI+7ePpbNJFSVSIUkPPocSgvgcAux/HuDqftzBgyAF3NGb3AAra1A8T7yPOqLyYyXdIJmF+/Svk5PdMbZVE/U76cjBThchQ9AiLo25hOjkmtuEQubCuwrUDleblr93aQIBEQ==-----结束 RSA 公钥-----

现在我想尝试这些以确保我没有出错但它不会加载:

$ openssl rsautl -encrypt -inkey key.pub -pubin -in data.txt -out enc.txt无法加载公钥

我错过了什么?

解决方案

int err = PEM_write_RSAPublicKey(pubwriter, key);

PEM_write_RSAPublicKey 只写入公钥.您可以使用 PEM_write_PUBKEY 使命令生效.各种*_PUBKEY 例程编写SubjectPublicKeyInfo,其中包括算法OID 和公钥.

当您编写 SubjectPublicKeyInfo 时,OpenSSL 将其称为传统"格式.它还将具有标题 -----BEGIN PUBLIC KEY----- (和 not ----- 开始 RSA 公钥-----).

下面,我用PEM_write_PUBKEY保存公钥rsa-public.pem:

$ openssl rsautl -encrypt -inkey rsa-public.pem -pubin -in data.txt -out enc.bin$ hexdump enc.bin0000000 45 53 31 ad 9d 6a c4 37 1e 22 4b 83 c6 27 c8 3c0000010 df cb 87 a4 60 d8 63 9a 83 9f ee ca e5 8f 8e dd0000020 d4 d0 98 97 1c b3 36 55 f1 84 ea 7f fe bf 22 b60000030 93 20 a2 d5 b2 bd 20 cc 52 8e c7 1b 33 e6 40 400000040 cb 7d 6f 17 f1 eb f1 d4 9d 66 fb 67 eb 67 ba 2a0000050 44 c2 52 15 54 8d 79 76 ad 26 61 35 27 9c bb 6c0000060 5b 0e 79 b3 d3 27 0b a9 72 17 0d 2d 19 d7 60 190000070 16 46 80 4b c0 ae 75 53 9e 6f f5 24 d9 1a a3 6a0000080 2f 38 13 f6 72 19 20 94 de 40 75 20 51 f4 08 f40000090 74 b8 ac 49 01 d6 f8 f4 e5 79 38 88 2d 02 b7 bd00000a0 f7 63 c1 e1 e5 ec 39 a1 fa 7c ce 0f 83 16 70 7e00000b0 cd 7e f5 6b 51 c2 db d7 f6 c4 46 5d e5 93 d3 3d00000c0 ab e6 3b 1a 97 d4 c9 54 e7 aa 90 2d 0a b9 c2 4b00000d0 3c 58 fd 26 58 5a 63 c0 8c ae b9 72 24 a1 68 5d00000e0 83 d7 5b ae 56 2a 78 46 8c f4 21 96 bd d3 0c 9300000f0 8e 35 61 9c b8 56 2e 3a 4e 05 d9 1e 0b 59 14 110000100

<小时>

PEM_write_PUBKEY 需要 EVP_PKEY.只需使用以下内容:

EVP_PKEY* pkey = EVP_PKEY_new();断言(pkey != NULL);int rc = EVP_PKEY_set1_RSA(pkey, rsa);断言(rc == 1);...EVP_PKEY_free(pkey);

set1 会增加 RSA 密钥上的引用计数,因此您必须通过 EVP_PKEY_free 释放它.

<小时>

PEM_write_RSAPublicKeyPEM_write_PUBKEY 的区别在 ASN.1/DER 中就很明显了.但它在 PEM 编码中丢失了.

这是 ASN.1/DER 中的非传统密钥并已转储.它是 PEM_write_RSAPublicKey 的 ASN.1 等效项.它只是 {n,e}:

$ dumpasn1 rsa-public-1.der0 266:序列{4 257:整数: 00 D1 C8 05 BF AC 04 72 AA 0E 84 FB 47 75 59 97: E1 81 65 0B 0A 1D 9D 2A A8 A1 E0 B1 14 5D 57 69: D4 D2 E2 C6 64 54 94 C2 92 CC C7 99 1A 97 89 72: F6 36 6A A7 B8 34 2C AB A9 CB 77 EB 0D A1 4E 72: 24 9F 96 D6 1C 28 ED 44 E8 0B 22 7F F3 5B 52 E2: 7E A6 5E F1 7C A2 29 4F F1 8B 9D 0F 94 27 05 D5:BD 2E 1A AD B4 12 0D E0 69 3E 0B 1B A7 F8 71 B5: AD 22 4B 18 FF 72 88 F3 C5 77 B0 CF 88 5C F4 19: [又跳过了 129 个字节]265 3:整数 65537:}0 个警告,0 个错误.

这是 ASN.1/DER 中的传统公钥并已转储.它相当于 PEM_write_PUBKEY 的 ASN.1.它是写SubjectPublicKeyInfo的那个,它包括一个算法OID和公钥:

$ dumpasn1 rsa-public-2.der0 290:序列{4 13:序列{6 9:对象标识符 rsaEncryption (1 2 840 113549 1 1 1)17 0:空:}19 271:位串,封装{24 266:序列{28 257:整数: 00 D1 C8 05 BF AC 04 72 AA 0E 84 FB 47 75 59 97: E1 81 65 0B 0A 1D 9D 2A A8 A1 E0 B1 14 5D 57 69: D4 D2 E2 C6 64 54 94 C2 92 CC C7 99 1A 97 89 72: F6 36 6A A7 B8 34 2C AB A9 CB 77 EB 0D A1 4E 72: 24 9F 96 D6 1C 28 ED 44 E8 0B 22 7F F3 5B 52 E2: 7E A6 5E F1 7C A2 29 4F F1 8B 9D 0F 94 27 05 D5:BD 2E 1A AD B4 12 0D E0 69 3E 0B 1B A7 F8 71 B5: AD 22 4B 18 FF 72 88 F3 C5 77 B0 CF 88 5C F4 19: [又跳过了 129 个字节]289 3:整数 65537:}:}:}0 个警告,0 个错误.

<小时><块引用>

 err = PEM_write_RSAPrivateKey(privwriter, key, EVP_des_ede3_cbc(),(unsigned char*)password.c_str(),密码.size(), NULL, NULL);

我相信 OpenSSL 人员建议您使用 PEM_write_PKCS8PrivateKey.请参阅 PEM(3)pkcs8(1).

<小时><块引用>

现在我想尝试这些以确保我没有出错但它不会加载:

 $ openssl rsautl -encrypt -inkey key.pub -pubin -in data.txt -out enc.txt

您可以通过查看 /apps/rsautl.c 来了解该行为.以下是相关行:

else if (!strcmp(*argv, "-pubin")) {key_type = KEY_PUBKEY;}...案例 KEY_PUBKEY:pkey = load_pubkey(bio_err, keyfile, keyform, 0, NULL, e, "Public Key");休息;...

然后,在 apps.c 中:

if (format == FORMAT_ASN1) {pkey = d2i_PUBKEY_bio(key, NULL);}...否则如果(格式== FORMAT_PEM){pkey = PEM_read_bio_PUBKEY(key, NULL, ...);}...

上面的观察是使用*_PUBKEY的例程.

还有一个基于format == FORMAT_PEMRSA的代码路径调用PEM_read_bio_RSAPublicKey,但我不知道如何触发它.看着 rsautl(1),我不不认为你可以,因为没有开关可以暴露它.

如果要触发,它将基于 -keyform 选项与 format == FORMAT_PEMRSA 的组合.但是 apps.cstr2fmt 不返回 FORMAT_PEMRSA.

我认为这意味着您唯一的选择是使用 SubjectPublicKeyInfo.这意味着使用 PEM_write_PUBKEY(或事后转换密钥).

<小时>

现在相关:OpenSSL 错误报告,问题 3887:rsautl 和智能重试公共传统/主题公钥信息解析失败后的密钥解析.

I've generated a public key using openssl

BIGNUM* e = BN_new();
BN_set_word(e, 17);
RSA* rsa = RSA_new();
if(!RSA_generate_key_ex(rsa, 2048, e, NULL)) {
    LOG(security, debug) << "failed to generate private key";
}

And these are written to files:

FILE* pubwriter = fopen("key.pub", "wb");
int err = PEM_write_RSAPublicKey(pubwriter, key);
if(!err) {
    throw new std::runtime_error("Failed to store public key");
}
FILE* privwriter = fopen("key.priv", "wb");
std::string password = "password";
err = PEM_write_RSAPrivateKey(privwriter, key, EVP_des_ede3_cbc(),
                                (unsigned char*)password.c_str(),
                                password.size(), NULL, NULL);

And they seem to be stored correctly, key.pub then contains something like

-----BEGIN RSA PUBLIC KEY-----
MIIBCAKCAQEA0rG1b0g3NIsDT8HkzgTx8BUI9LhueWbH1NuAvIh9qTF57GzEXuTu
jxBcuSzWXlR83ci4oITp7VqV6KLVoJryf8orGXBVi9A73JYOQVB6FEzARKym/g8E
fSEwSmdQ4NfiTESwOCtIextdu3x8pANSYDyyqdiWsSHy0SiZmkbvdVYomIBJZOV9
jhb3mkmD0WUYie9AXziTbli97YqDiN168kMI+7ePpbNJFSVSIUkPPocSgvgcAux/
HuDqftzBgyAF3NGb3AAra1A8T7yPOqLyYyXdIJmF+/Svk5PdMbZVE/U76cjBThch
Q9AiLo25hOjkmtuEQubCuwrUDleblr93aQIBEQ==
-----END RSA PUBLIC KEY-----

Now I want to try these to make sure I haven't got anything wrong but it wont' load:

$ openssl rsautl -encrypt -inkey key.pub -pubin -in data.txt -out enc.txt
unable to load Public Key

What am I missing?

解决方案

int err = PEM_write_RSAPublicKey(pubwriter, key);

PEM_write_RSAPublicKey writes just the public key. You can make the command work using PEM_write_PUBKEY. The various *_PUBKEY routines write the SubjectPublicKeyInfo, which includes the algorithm OID and public key.

When you write the SubjectPublicKeyInfo, OpenSSL calls it "traditional" format. It will also have the header -----BEGIN PUBLIC KEY----- (and not -----BEGIN RSA PUBLIC KEY-----).

Below, I used PEM_write_PUBKEY to save the public key rsa-public.pem:

$ openssl rsautl -encrypt -inkey rsa-public.pem -pubin -in data.txt -out enc.bin
$ hexdump enc.bin 
0000000 45 53 31 ad 9d 6a c4 37 1e 22 4b 83 c6 27 c8 3c
0000010 df cb 87 a4 60 d8 63 9a 83 9f ee ca e5 8f 8e dd
0000020 d4 d0 98 97 1c b3 36 55 f1 84 ea 7f fe bf 22 b6
0000030 93 20 a2 d5 b2 bd 20 cc 52 8e c7 1b 33 e6 40 40
0000040 cb 7d 6f 17 f1 eb f1 d4 9d 66 fb 67 eb 67 ba 2a
0000050 44 c2 52 15 54 8d 79 76 ad 26 61 35 27 9c bb 6c
0000060 5b 0e 79 b3 d3 27 0b a9 72 17 0d 2d 19 d7 60 19
0000070 16 46 80 4b c0 ae 75 53 9e 6f f5 24 d9 1a a3 6a
0000080 2f 38 13 f6 72 19 20 94 de 40 75 20 51 f4 08 f4
0000090 74 b8 ac 49 01 d6 f8 f4 e5 79 38 88 2d 02 b7 bd
00000a0 f7 63 c1 e1 e5 ec 39 a1 fa 7c ce 0f 83 16 70 7e
00000b0 cd 7e f5 6b 51 c2 db d7 f6 c4 46 5d e5 93 d3 3d
00000c0 ab e6 3b 1a 97 d4 c9 54 e7 aa 90 2d 0a b9 c2 4b
00000d0 3c 58 fd 26 58 5a 63 c0 8c ae b9 72 24 a1 68 5d
00000e0 83 d7 5b ae 56 2a 78 46 8c f4 21 96 bd d3 0c 93
00000f0 8e 35 61 9c b8 56 2e 3a 4e 05 d9 1e 0b 59 14 11
0000100


PEM_write_PUBKEY requires a EVP_PKEY. Just use something like:

EVP_PKEY* pkey = EVP_PKEY_new();
ASSERT(pkey != NULL);

int rc = EVP_PKEY_set1_RSA(pkey, rsa);
ASSERT(rc == 1);
...

EVP_PKEY_free(pkey);

The set1 bumps the reference count on the RSA key, so you have to free it through EVP_PKEY_free.


The difference between PEM_write_RSAPublicKey and PEM_write_PUBKEY is very obvious when you save in ASN.1/DER. But it gets lost in the PEM encoding.

Here's the non-traditional key in ASN.1/DER and dumped. Its the ASN.1 equivalent of PEM_write_RSAPublicKey. Its just {n,e}:

$ dumpasn1 rsa-public-1.der 
  0 266: SEQUENCE {
  4 257:   INTEGER
       :     00 D1 C8 05 BF AC 04 72 AA 0E 84 FB 47 75 59 97
       :     E1 81 65 0B 0A 1D 9D 2A A8 A1 E0 B1 14 5D 57 69
       :     D4 D2 E2 C6 64 54 94 C2 92 CC C7 99 1A 97 89 72
       :     F6 36 6A A7 B8 34 2C AB A9 CB 77 EB 0D A1 4E 72
       :     24 9F 96 D6 1C 28 ED 44 E8 0B 22 7F F3 5B 52 E2
       :     7E A6 5E F1 7C A2 29 4F F1 8B 9D 0F 94 27 05 D5
       :     BD 2E 1A AD B4 12 0D E0 69 3E 0B 1B A7 F8 71 B5
       :     AD 22 4B 18 FF 72 88 F3 C5 77 B0 CF 88 5C F4 19
       :             [ Another 129 bytes skipped ]
265   3:   INTEGER 65537
       :   }

0 warnings, 0 errors.

Here's the traditional public key in ASN.1/DER and dumped. Its the ASN.1 equivalent of PEM_write_PUBKEY. Its the one that writes the SubjectPublicKeyInfo, and it includes an algorithm OID and public key:

$ dumpasn1 rsa-public-2.der 
  0 290: SEQUENCE {
  4  13:   SEQUENCE {
  6   9:     OBJECT IDENTIFIER rsaEncryption (1 2 840 113549 1 1 1)
 17   0:     NULL
       :     }
 19 271:   BIT STRING, encapsulates {
 24 266:     SEQUENCE {
 28 257:       INTEGER
       :         00 D1 C8 05 BF AC 04 72 AA 0E 84 FB 47 75 59 97
       :         E1 81 65 0B 0A 1D 9D 2A A8 A1 E0 B1 14 5D 57 69
       :         D4 D2 E2 C6 64 54 94 C2 92 CC C7 99 1A 97 89 72
       :         F6 36 6A A7 B8 34 2C AB A9 CB 77 EB 0D A1 4E 72
       :         24 9F 96 D6 1C 28 ED 44 E8 0B 22 7F F3 5B 52 E2
       :         7E A6 5E F1 7C A2 29 4F F1 8B 9D 0F 94 27 05 D5
       :         BD 2E 1A AD B4 12 0D E0 69 3E 0B 1B A7 F8 71 B5
       :         AD 22 4B 18 FF 72 88 F3 C5 77 B0 CF 88 5C F4 19
       :                 [ Another 129 bytes skipped ]
289   3:       INTEGER 65537
       :       }
       :     }
       :   }

0 warnings, 0 errors.


 err = PEM_write_RSAPrivateKey(privwriter, key, EVP_des_ede3_cbc(),
                            (unsigned char*)password.c_str(),
                            password.size(), NULL, NULL);

I believe the OpenSSL folks recommend you use PEM_write_PKCS8PrivateKey. See PEM(3) and pkcs8(1).


Now I want to try these to make sure I haven't got anything wrong but it wont' load:

 $ openssl rsautl -encrypt -inkey key.pub -pubin -in data.txt -out enc.txt

You can understand the behavior by looking at <openssl src>/apps/rsautl.c. Here are the relevant lines:

else if (!strcmp(*argv, "-pubin")) {
    key_type = KEY_PUBKEY;
}
...

case KEY_PUBKEY:
    pkey = load_pubkey(bio_err, keyfile, keyform, 0, NULL, e, "Public Key");
    break;
...

Then, in apps.c:

if (format == FORMAT_ASN1) {
    pkey = d2i_PUBKEY_bio(key, NULL);
}
...

else if (format == FORMAT_PEM) {
    pkey = PEM_read_bio_PUBKEY(key, NULL, ...);
}
...

The observation above is the routines are using *_PUBKEY.

There's also a code path based on format == FORMAT_PEMRSA that calls PEM_read_bio_RSAPublicKey, but I don't know how to trigger it. Looking at rsautl(1), I don't think you can because there's no switch that exposes it.

If it was going to trigger, it would be based on a combination of the -keyform option combined with format == FORMAT_PEMRSA. But apps.c's str2fmt does not return a FORMAT_PEMRSA.

I think that means your only option is to use a SubjectPublicKeyInfo. And that means using PEM_write_PUBKEY (or convert the key after the fact).


Now related: OpenSSL Bug Report, Issue 3887: rsautl and intelligent retry for Public Key parse after Traditional/Subject Public Key Info parse fails.

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