前    言

前几个月记录了使用Java生成根证书并签署下级证书的例子，然而细心地朋友会发现使用Java有很多局限性，比如说“增强型密钥用法”无法添加（也许是我不会添加）导致证书功能受限。

今天记录使用OpenSSL生成真正的证书

实际操作

生成根证书

1.使用命令生成私钥

openssl genrsa -aes256 -passout pass:设定私钥密码 -out prikey.pem 8192

其中：

“-aes256”为加密算法，OpenSSL支持常见的算法，甚至还支持一些不常用的算法，根据国际标准建议采用AES256位加密算法，在安全性和实用性（例如处理器硬件支持）上都有良好表现。

“-out”后面为输出文件名

“8192”为密钥长度，理论上越长越安全，最低安全标准为1024位，根据RSA的加密原理，在不出现算法捷径情况下其安全性主要依赖于密钥长度。

2.为方便使用将私钥解密

openssl rsa -in prikey.pem -out unenprikey.pem -passin pass:设定私钥密码

3.根据私钥生成自签名证书

openssl req -new -x509 -key unenprikey.pem -days 18250 -out cert.crt -sha512 -config ./openssl.cnf -subj /OU=某某部门/O=某某集团/C=国家（英文字符，如CN）/CN=证书通用名

其中：

“-days”后面的数字指证书有效时间

“-sha512”指混淆算法，同加密算法一样支持较多参数，给出的推荐参数为最优选项

“-config”后面的文件是指OpenSSL的配置文件，配置文件内容指定了证书的策略以及规则

“-subj”后面是定义证书使用者参数，若不加入此参数也会在生成证书时根据OpenSSL配置文件中的配置要求现场填写

签署下级证书

1.同根证书一样生成私钥并解密

2.根据私钥生成签名请求文件

openssl req -new -key unenprikey.pem -days 2190 -out cert.csr -sha512 -config ./openssl.cnf -subj /OU=某某部门/O=某某集团/C=国家（英文字符，如CN）/CN=证书通用名

3.使用根证书的证书文件、私钥文件签署下级证书

根据OpenSSL配置文件中的配置，部署根证书以及根证书密钥到指定位置，并建立对应功能的工作文件夹（少做一步都会报错）

openssl ca -in cert.csr -config ./openssl.cnf

签署后的证书文件会生成在OpenSSL配置文件指定的目录中

附    录

OpenSSL配置文件配置解析

我使用的OpenSSL文件内容如下：

内容做了很多注释、调整与汉化方便调节与理解

########################
# OpenSSL 证书配置文件   #
########################

# 如果未定义HOME后续参数将不会生效
HOME			= .
RANDFILE		= $ENV::HOME/.rnd

# 附加 OBJECT IDENTIFIER 信息:
#oid_file		= $ENV::HOME/.oid
oid_section		= new_oids

# To use this configuration file with the "-extfile" option of the
# "openssl x509" utility, name here the section containing the
# X.509v3 extensions to use:
# extensions		= 
# (Alternatively, use a configuration file that has only
# X.509v3 extensions in its main [= default] section.)

[ new_oids ]

# 我们可以在这里添加新的 OIDs 以供下面的 'ca', 'req' 和 'ts' 使用.
# 添加示例:
# testoid1=1.2.3.4
# 或者像这样引用上方声明的配置:
# testoid2=${testoid1}.5.6

# TSA策略
tsa_policy1 = 1.2.3.4.1
tsa_policy2 = 1.2.3.4.5.6
tsa_policy3 = 1.2.3.4.5.7

##############################################基础配置区 - 开始######################################################


####################################################################
[ ca ]
default_ca	= Certificate_Config		# 选择默认的证书基础配置区

####################################################################

[ Certificate_Config ]

dir				= /usr/CA				# 设定工作目录
certs				= $dir/"Root CA"			# CA证书保存位置
certificate			= $dir/"Root CA"/CA.crt 		# CA证书文件位置
private_key			= $dir/"Root CA"/CA.key			# CA证书私钥位置
RANDFILE			= $dir/"Root CA"/.rand			# CA证书私钥随机数文件
database			= $dir/Data/database			# 数据库索引文件
serial				= $dir/Data/serial 			# 序列号索引文件
#unique_subject		= no						# 设置为 'no' 则允许创建多个具有相同主题的证书
new_certs_dir		= $dir/"Sign Certs"				# 签署下级证书保存位置


crl_dir				= $dir/Crl				# 发行crl文件位置
crl					= $dir/Crl/crl.pem 		# 当前的CRL文件
crlnumber			= $dir/Crl/crlnumber			# crl编号文件
					# must be commented out to leave a V1 CRL

					
#被签署证书的扩展规则（选择是CA证书还是用户证书）
x509_extensions		= usr_cert					# 用户证书
#x509_extensions	= v3_ca						# CA证书

# Comment out the following two lines for the "traditional"
# (and highly broken) format.
name_opt 	= ca_default				        	# Subject Name options
cert_opt 	= ca_default				        	# Certificate field options

# 扩展复制选项: 谨慎使用.
# copy_extensions = copy

# 添加到 CRL 的扩展. Note:定义生成CRL时需要加入的扩展项字段。如果注释则生成v1而不是v2版本的CRL。
# crl_extensions	= crl_ext

default_days	= 5475			                        	# CA证书的有效时长
default_crl_days= 30			                        	# how long before next CRL
default_md	= sha512			                	# 公钥混淆算法
preserve	= no					                # keep passed DN ordering

# CA使用者配置区域选择
policy		= policy_match

# CA使用者配置区域
[ policy_match ]
countryName		= match
stateOrProvinceName	= optional
organizationName	= match
organizationalUnitName	= optional
commonName		= supplied
emailAddress		= optional

# 其他任何证书配置
# 您必须列出所有可以接受的 'object' 类型
[ policy_anything ]
countryName		= optional
stateOrProvinceName	= optional
localityName		= optional
organizationName	= optional
organizationalUnitName	= optional
commonName		= supplied
emailAddress		= optional

####################################################################


##############################################签署用户证书控制区开始######################################################

[ usr_cert ]

# 当CA签署请求时会应用下列扩展

# 是否为CA证书
basicConstraints=CA:FALSE

# 以下是 nsCertType 使用的一些示例.
# 如果忽略该证书则可用于除对象签名之外的任何事情

# SSL服务.
# nsCertType			= server

# 对象签名证书
# nsCertType = objsign

# 使用场景
# nsCertType = client, email, objsign

# 这是一个客户端证书中 keyUsage 的典型.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment

# 内容将显示在Netscape comment框中
#nsComment			= "OpenSSL Generated Certificate"

# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer

# subjectAltName 和 issuerAltname 配置
# 导入电子邮件地址
# subjectAltName=email:copy
# 根据PKIX生成不被弃用的证书替代方案
# deprecated according to PKIX.
# subjectAltName=email:move

# Copy subject details
# issuerAltName=issuer:copy

#nsCaRevocationUrl		= http://www.domain.dom/ca-crl.pem
#nsBaseUrl
#nsRevocationUrl
#nsRenewalUrl
#nsCaPolicyUrl
#nsSslServerName

# 这是 TSA 证书必要选项.增强型秘钥用法
# extendedKeyUsage = critical,timeStamping

##############################################签署用户证书控制区结束######################################################


##############################################CA证书控制区开始######################################################
[ v3_ca ]

subjectKeyIdentifier=hash

authorityKeyIdentifier=keyid:always,issuer

basicConstraints = critical,CA:true

# 密钥用法: 这是CA证书的标准用法. 

keyUsage = cRLSign, keyCertSign, nonRepudiation, digitalSignature, keyAgreement, keyEncipherment, dataEncipherment

#这是 TSA 证书必要选项.增强型秘钥用法
extendedKeyUsage = critical,timeStamping,codeSigning,serverAuth,clientAuth,msCTLSign,1.3.6.1.5.5.8.2.2,emailProtection,1.3.6.1.4.1.311.10.3.11,msEFS,1.3.6.1.4.1.311.20.2.2

# 有些时候可能需要下列配置
# nsCertType = sslCA, emailCA

# Include email address in subject alt name: another PKIX recommendation
# subjectAltName=email:copy
# Copy issuer details
# issuerAltName=issuer:copy

# DER hex encoding of an extension: beware experts only!
# obj=DER:02:03
# Where 'obj' is a standard or added object
# You can even override a supported extension:
# basicConstraints= critical, DER:30:03:01:01:FF

##############################################CA证书控制区结束######################################################



#####################################################################

##############################################自签名证书控制区开始######################################################
[ req ]

default_bits		= 8192							#默认密钥长度
default_keyfile 	= privkey.pem				        	#默认密钥文件
distinguished_name	= req_distinguished_name		                #证书信息规则
attributes			= req_attributes				#证书密码规则
x509_extensions		= usr_cert						#添加到自签名证书的扩展

# 私钥密码,如果未设置将会提示输入
input_password = ************
output_password = ************

# 设定编码类型(用于支持多平台与语言). 有如下选择 
# default: PrintableString, T61String, BMPString.
# pkix	 : PrintableString, BMPString (PKIX recommendation before 2004)
# utf8only: 只使用 UTF8Strings (PKIX recommendation after 2004).
# nombstr : PrintableString, T61String (不使用 BMPStrings 或 UTF8Strings).
# MASK:XXXX a literal mask value.
# 警告: 老版本的 Netscape crash 在 BMPStrings 或 UTF8Strings 中崩溃.
string_mask = utf8only

##############################################自签名证书控制区结束######################################################

[ req_distinguished_name ]
countryName			= 国家名称 (两个字母的简称)
countryName_default	= CN
countryName_min		= 2
countryName_max		= 2

stateOrProvinceName	= 州或省的名称 (全名)
#stateOrProvinceName_default= Some-State

localityName		= 地区名称 (例如:城市,直辖市区)

0.organizationName	= 组织名称 (例如:公司,非营利性组织)
# 可以加入多个组织名称,通常不需要
#0.organizationName_default	= Internet Widgits Pty Ltd
#1.organizationName	= Second Organization Name (eg, company)
#1.organizationName_default	= World Wide Web Pty Ltd

organizationalUnitName= 组织单位名称 (例如:部分,科室)
#organizationalUnitName_default	=

commonName			= 通用名称 (e.g. 域名 or YOUR name)
commonName_max		= 64

emailAddress		= Email地址
emailAddress_max	= 64

# SET-ex3			= SET extension number 3



[ req_attributes ]
challengePassword	= 一个高强度的密码(4-20位)
challengePassword_min= 4
challengePassword_max= 20
unstructuredName	= 可选的公司名称


[ crl_ext ]

# CRL extensions.
# Only issuerAltName and authorityKeyIdentifier make any sense in a CRL.

# issuerAltName=issuer:copy
authorityKeyIdentifier=keyid:always

[ proxy_cert_ext ]
# These extensions should be added when creating a proxy certificate

# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.

basicConstraints=CA:FALSE

# Here are some examples of the usage of nsCertType. If it is omitted
# the certificate can be used for anything *except* object signing.

# This is OK for an SSL server.
# nsCertType			= server

# For an object signing certificate this would be used.
# nsCertType = objsign

# For normal client use this is typical
# nsCertType = client, email

# and for everything including object signing:
# nsCertType = client, email, objsign

# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment

# This will be displayed in Netscape's comment listbox.
nsComment			= "OpenSSL Generated Certificate"

# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer

# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy
# An alternative to produce certificates that aren't
# deprecated according to PKIX.
# subjectAltName=email:move

# Copy subject details
# issuerAltName=issuer:copy

#nsCaRevocationUrl		= http://www.domain.dom/ca-crl.pem
#nsBaseUrl
#nsRevocationUrl
#nsRenewalUrl
#nsCaPolicyUrl
#nsSslServerName

# This really needs to be in place for it to be a proxy certificate.
proxyCertInfo=critical,language:id-ppl-anyLanguage,pathlen:3,policy:foo

####################################################################
[ tsa ]

default_tsa = tsa_config1	# the default TSA section

[ tsa_config1 ]

# These are used by the TSA reply generation only.
dir		= /usr/CA		# TSA root directory
serial		= $dir/tsaserial	# The current serial number (mandatory)
crypto_device	= builtin		# OpenSSL engine to use for signing
signer_cert	= $dir/tsacert.pem 	# The TSA signing certificate
					# (optional)
certs		= $dir/cacert.pem	# Certificate chain to include in reply
					# (optional)
signer_key	= $dir/private/tsakey.pem # The TSA private key (optional)
signer_digest  = sha512			# Signing digest to use. (Optional)
default_policy	= tsa_policy1		# Policy if request did not specify it
					# (optional)
other_policies	= tsa_policy2, tsa_policy3	# acceptable policies (optional)
digests     = sha1, sha256, sha384, sha512  # Acceptable message digests (mandatory)
accuracy	= secs:1, millisecs:500, microsecs:100	# (optional)
clock_precision_digits  = 0	# number of digits after dot. (optional)
ordering		= yes	# Is ordering defined for timestamps?
				# (optional, default: no)
tsa_name		= yes	# Must the TSA name be included in the reply?
				# (optional, default: no)
ess_cert_id_chain	= no	# Must the ESS cert id chain be included?
				# (optional, default: no)
ess_cert_id_alg		= sha512	# algorithm to compute certificate
				# identifier (optional, default: sha1)