openssl生成自签SSL证书

Overview

The following is an extremely simplified view of how SSL is implemented and what part the certificate plays in the entire process.

Normal web traffic is sent unencrypted over the Internet. That is, anyone with access to the right tools can snoop all of that traffic. Obviously, this can lead to problems, especially where security and privacy is necessary, such as in credit card data and bank transactions. The Secure Socket Layer is used to encrypt the data stream between the web server and the web client (the browser).

SSL makes use of what is known as asymmetric cryptography, commonly referred to as public key cryptography (PKI). With public key cryptography, two keys are created, one public, one private. Anything encrypted with either key can only be decrypted with its corresponding key. Thus if a message or data stream were encrypted with the server’s private key, it can be decrypted only using its corresponding public key, ensuring that the data only could have come from the server.

If SSL utilizes public key cryptography to encrypt the data stream traveling over the Internet, why is a certificate necessary? The technical answer to that question is that a certificate is not really necessary – the data is secure and cannot easily be decrypted by a third party. However, certificates do serve a crucial role in the communication process. The certificate, signed by a trusted Certificate Authority (CA), ensures that the certificate holder is really who he claims to be. Without a trusted signed certificate, your data may be encrypted, however, the party you are communicating with may not be whom you think. Without certificates, impersonation attacks would be much more common.

Step 1: Generate a Private Key

The openssl toolkit is used to generate an RSA Private Key and CSR (Certificate Signing Request). It can also be used to generate self-signed certificates which can be used for testing purposes or internal usage.

The first step is to create your RSA Private Key. This key is a 1024 bit RSA key which is encrypted using Triple-DES and stored in a PEM format so that it is readable as ASCII text.

openssl genrsa -des3 -out server.key 1024

Generating RSA private key, 1024 bit long modulus
…………………………………………………++++++
……..++++++
e is 65537 (0x10001)
Enter PEM pass phrase:
Verifying password – Enter PEM pass phrase:

Step 2: Generate a CSR (Certificate Signing Request)

Once the private key is generated a Certificate Signing Request can be generated. The CSR is then used in one of two ways. Ideally, the CSR will be sent to a Certificate Authority, such as Thawte or Verisign who will verify the identity of the requestor and issue a signed certificate. The second option is to self-sign the CSR, which will be demonstrated in the next section.

During the generation of the CSR, you will be prompted for several pieces of information. These are the X.509 attributes of the certificate. One of the prompts will be for “Common Name (e.g., YOUR name)”. It is important that this field be filled in with the fully qualified domain name of the server to be protected by SSL. If the website to be protected will be https://public.akadia.com, then enter public.akadia.com at this prompt. The command to generate the CSR is as follows:

openssl req -new -key server.key -out server.csr

Country Name (2 letter code) [GB]:CH
State or Province Name (full name) [Berkshire]:Bern
Locality Name (eg, city) [Newbury]:Oberdiessbach
Organization Name (eg, company) [My Company Ltd]:Akadia AG
Organizational Unit Name (eg, section) []:Information Technology
Common Name (eg, your name or your server’s hostname) []:public.akadia.com
Email Address []:martin dot zahn at akadia dot ch
Please enter the following ‘extra’ attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

Step 3: Remove Passphrase from Key

One unfortunate side-effect of the pass-phrased private key is that Apache will ask for the pass-phrase each time the web server is started. Obviously this is not necessarily convenient as someone will not always be around to type in the pass-phrase, such as after a reboot or crash. mod_ssl includes the ability to use an external program in place of the built-in pass-phrase dialog, however, this is not necessarily the most secure option either. It is possible to remove the Triple-DES encryption from the key, thereby no longer needing to type in a pass-phrase. If the private key is no longer encrypted, it is critical that this file only be readable by the root user! If your system is ever compromised and a third party obtains your unencrypted private key, the corresponding certificate will need to be revoked. With that being said, use the following command to remove the pass-phrase from the key:

cp server.key server.key.org
openssl rsa -in server.key.org -out server.key

The newly created server.key file has no more passphrase in it.

-rw-r–r– 1 root root 745 Jun 29 12:19 server.csr
-rw-r–r– 1 root root 891 Jun 29 13:22 server.key
-rw-r–r– 1 root root 963 Jun 29 13:22 server.key.org

Step 4: Generating a Self-Signed Certificate

At this point you will need to generate a self-signed certificate because you either don’t plan on having your certificate signed by a CA, or you wish to test your new SSL implementation while the CA is signing your certificate. This temporary certificate will generate an error in the client browser to the effect that the signing certificate authority is unknown and not trusted.

To generate a temporary certificate which is good for 365 days, issue the following command:

openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt
Signature ok
subject=/C=CH/ST=Bern/L=Oberdiessbach/O=Akadia AG/OU=Information
Technology/CN=public.akadia.com/Email=martin dot zahn at akadia dot ch
Getting Private key

Step 5: Installing the Private Key and Certificate

When Apache with mod_ssl is installed, it creates several directories in the Apache config directory. The location of this directory will differ depending on how Apache was compiled.

cp server.crt /usr/local/apache/conf/ssl.crt
cp server.key /usr/local/apache/conf/ssl.key

Step 6: Configuring SSL Enabled Virtual Hosts

SSLEngine on
SSLCertificateFile /usr/local/apache/conf/ssl.crt/server.crt
SSLCertificateKeyFile /usr/local/apache/conf/ssl.key/server.key
SetEnvIf User-Agent “.*MSIE.*” nokeepalive ssl-unclean-shutdown
CustomLog logs/ssl_request_log \
“%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \”%r\” %b”

Step 7: Restart Apache and Test

/etc/init.d/httpd stop
/etc/init.d/httpd stop

openssl生成自签证书

要 生成证书的目录下建立几个文件和文件夹,有./demoCA/ ./demoCA/newcerts/ ./demoCA/index.txt ./demoCA/serial,在serial文件中写入第一个序列号01 1.生成X509格式的CA自签名证书 $ openssl req -new -x509 -keyout ca.key -out ca.crt 2.生成服务端的私钥
要生成证书的目录下建立几个文件和文件夹,有./demoCA/ ./demoCA/newcerts/ ./demoCA/index.txt ./demoCA/serial,在serial文件中写入第一个序列号“01”

1.生成X509格式的CA自签名证书
$openssl req -new -x509 -keyout ca.key -out ca.crt
2.生成服务端的私钥(key文件)及csr 文件
$openssl genrsa -des3 -out server.key 1024
$openssl req -new -key server.key -out server.csr

3.生成客户端的私钥(key文件)及csr文件
$openssl genrsa -des3 -out client.key 1024
$openssl req -new -key client.key -out client.csr

4.用生成的CA的证书为刚才生成的server.csr,client.csr文件签名
$openssl ca -in server.csr -out server.crt -cert ca.crt -keyfile ca.key
$openssl ca -in client.csr -out client.crt -cert ca.crt -keyfile ca.key
5. 生成p12格式证书
$openssl pkcs12 -export -inkey client.key -in client.crt -out client.pfx
$openssl pkcs12 -export -inkey server.key -in server.crt -out server.pfx

6.生成pem格式证书
有时需要用到pem格式的证书,可以用以下方式合并证书文件(crt)和私钥文件(key)来生成
$cat client.crt client.key> client.pem
$cat server.crt server.key > server.pem

7.PFX文件转换为X509证书文件和RSA密钥文件
$openssl pkcs12 -in server.pfx -nodes -out server.pem
$openssl rsa -in server.pem -out server2.key
$openssl x509 -in server.pem -out server2.crt

这样生成服务端证书:ca.crt, server.key, server.crt, server.pem, server.pfx,客户端证书:ca.crt, client.key, client.crt, client.pem, client.pfx

Creating a self-signed test certificate

If you don’t want to deal with another certificate authority, or just
want to create a test certificate for yourself.  This is similar to
creating a certificate request, but creates a certificate instead of
a certificate request.  This is NOT the recommended way to create a
CA certificate, see ca.txt.

openssl req -new -x509 -key privkey.pem -out cacert.pem -days 1095

How to create a test certificate?

Step one – create the key and request:

openssl req -new > new.cert.csr

Step two – remove the passphrase from the key (optional):

openssl rsa -in privkey.pem -out new.cert.key

Step three – convert request into signed cert:

openssl x509 -in new.cert.csr -out new.cert.cert -req -signkey new.cert.key -days 1825

Step four – copy the cert and key to the appropriate places

cp new.cert.cert /etc/apache/ssl.crt/server.crt
cp new.cert.key /etc/apache/ssl.key/server.key

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