EXP(ORT)密码和M2Crypto/OpenSSL

Question

EXP(ORT)密码和M2Crypto/OpenSSL

sta*_*arm 14 python openssl cryptography pyopenssl m2crypto

我很难运行带有EXPORT级密码的M2Crypto SSLServer.

LOW/MEDIUM/HIGH级密码的工作没有任何问题,但EXPORT不会.此外,当OpenSSL从命令行以服务器模式运行时,它接受EXPORT级密码而没有任何问题.

所以,要么我丢失了某些东西,要么M2Crypto模块中存在问题.任何帮助表示赞赏.

使用过的python代码(ssl-server.py)如下所示:

import M2Crypto
import socket

CERTFILE = "dummy_cert.pem"
KEYFILE = "dummy_key.pem"
PROTOCOL = "sslv3"
HOST = "0.0.0.0"
PORT = 4433

def main():
    print "[i] Initializing context ..."
    ctx = M2Crypto.SSL.Context(protocol=PROTOCOL, weak_crypto=True)
    ctx.load_cert_chain(certchainfile=CERTFILE, keyfile=KEYFILE)
    ctx.set_options(M2Crypto.m2.SSL_OP_ALL)
    ctx.set_cipher_list("ALL")

    print "[i] Initializing socket ..."
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.bind((HOST, PORT))
    sock.listen(1)
    conn, addr = sock.accept()

    print "[i] SSL handshake ..."
    ssl_conn = M2Crypto.SSL.Connection(ctx=ctx, sock=conn)
    ssl_conn.setup_ssl()
    try:
        ssl_conn_res = ssl_conn.accept_ssl()
    except Exception, ex:
        print "[x] SSL connection failed: '%s'" % str(ex)
    else:
        if ssl_conn_res == 1:
            print "[i] SSL connection accepted"
        else:
            print "[x] SSL handshake failed: '%s'" % ssl_conn.ssl_get_error(ssl_conn_res)

if __name__ == "__main__":
    main()

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症状是:

$ uname -a
Linux XYZ 2.6.38-15-generic #59-Ubuntu SMP Fri Apr 27 16:03:32 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=11.04
DISTRIB_CODENAME=natty
DISTRIB_DESCRIPTION="Ubuntu 11.04"

$ python -c "import M2Crypto;print M2Crypto.version_info"
(0, 20, 1)

$ openssl version
OpenSSL 0.9.8o 01 Jun 2010

1) NOT OK
SERVER (terminal 1): $ python ssl-server.py
CLIENT (terminal 2): $ openssl s_client -connect localhost:4433 -cipher EXPORT
CONNECTED(00000003)
28131:error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handshake failure:s23_clnt.c:602:

2) OK
SERVER (terminal 1): $ openssl s_server -cert dummy_cert.pem -key dummy_key.pem -ssl3 -no_tls1 -no_ssl2 -cipher EXPORT
CLIENT (terminal 2): $ openssl s_client -connect localhost:4433 -cipher EXPORT
CONNECTED(00000003)
depth=0 C = BE, CN = www.example.com
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 C = BE, CN = www.example.com
verify error:num=27:certificate not trusted
verify return:1
depth=0 C = BE, CN = www.example.com
verify error:num=21:unable to verify the first certificate
verify return:1
---
Certificate chain
 0 s:/C=BE/CN=www.example.com
   i:/C=BE/CN=test-ca
---
Server certificate
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
subject=/C=BE/CN=www.example.com
issuer=/C=BE/CN=test-ca
---
No client certificate CA names sent
---
SSL handshake has read 1141 bytes and written 242 bytes
---
New, TLSv1/SSLv3, Cipher is EXP-EDH-RSA-DES-CBC-SHA
Server public key is 1024 bit
Secure Renegotiation IS supported
Compression: zlib compression
Expansion: zlib compression
SSL-Session:
    Protocol  : SSLv3
    Cipher    : EXP-EDH-RSA-DES-CBC-SHA
    Session-ID: B052D5D5A436F9A0B9D3FB24F2E32A8A06A0B6828230621C4CFAEB82A0A9AE0C
    Session-ID-ctx: 
    Master-Key:     47F6E3720D06518B961FE389F13BCDE42C37F703099ABBB9B3DA35383C420F519D4F4773D35E470CF6FF7BB243B29069
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    Compression: 1 (zlib compression)
    Start Time: 1340644713
    Timeout   : 300 (sec)
    Verify return code: 21 (unable to verify the first certificate)
---

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a的内容dummy_cert.pem如下:

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a的内容dummy_key.pem如下:

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更新:在低级别握手数据包似乎是相同的,除了该random[32]字段使这更奇怪.

ssldump -a -A -H -i lo两种情况的SSL dump()都可以在这里找到:

http://pastebin.com/YuC7d8zg(不是好的情况)

http://pastebin.com/U6YGQmv9(OK案例)

Answer 1

Dan*_*ger 5

我需要对python脚本进行以下两个调整,以使其适用于导出密码套件:

PROTOCOL = "sslv23"
...
    print "[i] Initializing context ..."
    ctx = M2Crypto.SSL.Context(protocol=PROTOCOL, weak_crypto=True)
    ctx.load_cert_chain(certchainfile=CERTFILE, keyfile=KEYFILE)
    ctx.set_options(M2Crypto.m2.SSL_OP_ALL)
    ctx.set_tmp_rsa(M2Crypto.RSA.gen_key(512, 65537))
    ctx.set_cipher_list("ALL")

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那是:

使用SSLv23作为协议标识符(SSLv2/v3 compat模式).不知道为什么在这种情况下需要它,但似乎不起作用.
使用在上下文中设置临时的短暂RSA密钥set_tmp_rsa().这是必需的,因为使用导出密码时,提供的(1024位)RSA密钥仅用于身份验证(签名),而临时的,导出残缺的512位RSA密钥用于机密性(加密).OpenSSL要求您在上下文中设置此密钥(请参阅SSL_set_tmp_rsa()的文档).

古怪的是,它也适用于的SSLv2-only模式(使用-ssl2上openssl s_client进行测试时)不设置一个临时的RSA密钥(调用set_tmp_rsa脚本注释掉).我不知道为什么.

通常,一些密码套件需要将特殊键添加到上下文中,例如使用DH(组参数)或ECDH(曲线)的套件.要准确了解每个密码套件的用途,openssl ciphers -v可以很有见地,例如:

% openssl ciphers -v EXPORT
EXP-EDH-RSA-DES-CBC-SHA SSLv3 Kx=DH(512)  Au=RSA  Enc=DES(40)   Mac=SHA1 export
EXP-EDH-DSS-DES-CBC-SHA SSLv3 Kx=DH(512)  Au=DSS  Enc=DES(40)   Mac=SHA1 export
EXP-ADH-DES-CBC-SHA     SSLv3 Kx=DH(512)  Au=None Enc=DES(40)   Mac=SHA1 export
EXP-DES-CBC-SHA         SSLv3 Kx=RSA(512) Au=RSA  Enc=DES(40)   Mac=SHA1 export
EXP-RC2-CBC-MD5         SSLv3 Kx=RSA(512) Au=RSA  Enc=RC2(40)   Mac=MD5  export
EXP-RC2-CBC-MD5         SSLv2 Kx=RSA(512) Au=RSA  Enc=RC2(40)   Mac=MD5  export
EXP-ADH-RC4-MD5         SSLv3 Kx=DH(512)  Au=None Enc=RC4(40)   Mac=MD5  export
EXP-RC4-MD5             SSLv3 Kx=RSA(512) Au=RSA  Enc=RC4(40)   Mac=MD5  export
EXP-RC4-MD5             SSLv2 Kx=RSA(512) Au=RSA  Enc=RC4(40)   Mac=MD5  export

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编辑重新回答有关DSS密码套件的问题:

DSS/DSA密码套件需要DH参数,当然还有基于DSS/DSA的服务器证书,而不是(仅)RSA密码.这不仅适用于导出密码套件,也适用于使用DSS/DSA实现真实性的所有套件.DSS/DSA只能用于签名,而不能用于加密,以便允许导出到不受信任的国家/地区.由于DSS/DSA只能用于签名,因此需要短暂的Diffie-Hellman密钥交换来建立共享会话密钥.这就是密码套件中的EDH所代表的含义.要设置DH参数,您可以使用OpenSSL SSL_set_tmp_dh() API 的M2Crypto等效项.

请注意,OpenSSL允许将RSA和DSA/DSS证书/密钥对加载到同一SSL上下文中.

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