疑今者察之古，不知来者视之往。
导航
介绍
密码学标准和互联网协议一样，是一种大家都遵守的约定和标准，比如PKCS#1中规定了 RSA 秘钥是怎么生成的、公私钥的格式 等内容，x509标准规定了证书的格式等。
OpenSSL 本质就是一个工具集，按照主流的密码学标准实现了常用的加密算法，证书的生成、签名、验签等功能。
对称加密
对称密钥算法在加密和解密时使用相同的密钥进行处理，这类算法众多可通过 openssl list -cipher-commands 具体查看。
（1）openssl子命令enc为对称加解密工具，还可以进行base64编码转换。
$ openssl enc --help
Usage: enc [options]
General options:
-help Display this summary
-list List ciphers
-ciphers Alias for -list
-e Encrypt
-d Decrypt
-p Print the iv/key
-P Print the iv/key and exit
-engine val Use engine, possibly a hardware device
Input options:
-in infile Input file
-k val Passphrase
-kfile infile Read passphrase from file
Output options:
-out outfile Output file
-pass val Passphrase source
-v Verbose output
-a Base64 encode/decode, depending on encryption flag
-base64 Same as option -a
-A Used with -[base64|a] to specify base64 buffer as a single line
Encryption options:
-nopad Disable standard block padding
-salt Use salt in the KDF (default)
-nosalt Do not use salt in the KDF
-debug Print debug info
-bufsize val Buffer size
-K val Raw key, in hex
-S val Salt, in hex
-iv val IV in hex
-md val Use specified digest to create a key from the passphrase
-iter +int Specify the iteration count and force use of PBKDF2
-pbkdf2 Use password-based key derivation function 2
-none Don't encrypt
-* Any supported cipher
Random state options:
-rand val Load the given file(s) into the random number generator
-writerand outfile Write random data to the specified file
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
示例一：使用一种加密算法加密文件
// 通过aes-128-cbc对称密钥算法对文件test.txt进行加密，共享密钥是pass，输出文件是test-aes-enc.txt。
openssl enc -e -aes-128-cbc -in test.txt -k pass -out test-aes-enc.txt -v
// 通过aes-128-cbc对称密钥算法对文件test-aes-enc.txt进行解密，共享密钥是pass，输出文件是test-aes-dec.txt。
openssl enc -d -aes-128-cbc -in test-aes-enc.txt -k 123 -out test-aes-dec.txt -v
公钥加密
公钥密钥算法在加密和解密时分别使用不同的密钥进行处理（一般 公钥加密，私钥解密；而签名则相反：私钥加密，公钥解密），这类算法目前只支持DH算法、RSA算法、DSA算法和椭圆曲线算法（EC）。DH算法一般用于密钥交换。RSA算法可用于密钥交换、数字签名及数据加密。DSA算法一般只用于数字签名。此处只重点介绍RSA相关指令genrsa、rsa、rsautl的使用。
（1）openssl子命令genrsa主要用于生成RSA私钥。
$ openssl genrsa --help
Usage: genrsa [options] numbits
General options:
-help Display this summary
-engine val Use engine, possibly a hardware device
Input options:
-3 (deprecated) Use 3 for the E value
-F4 Use the Fermat number F4 (0x10001) for the E value
-f4 Use the Fermat number F4 (0x10001) for the E value
Output options:
-out outfile Output the key to specified file
-passout val Output file pass phrase source
-primes +int Specify number of primes
-verbose Verbose output
-traditional Use traditional format for private keys
-* Encrypt the output with any supported cipher
Random state options:
-rand val Load the given file(s) into the random number generator
-writerand outfile Write random data to the specified file
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
Parameters:
numbits Size of key in bits
示例一：生成无密码且1024字节长度的私钥
openssl genrsa -out private.pem 1024 -verbose
示例二：生成带密码的私钥（genrsa生成的私钥格式都是PEM格式）--PEM、DER格式区别
// 使用aes-128-cbc对称加密算法对私钥进行加密处理，命令执行之后会提示输入密码
openssl genrsa -aes-128-cbc -out pri.pem -verbose
（2）openssl子命令rsa用于处理rsa密钥（提取公钥、管理保护密码）、格式转换和打印信息。
$ openssl rsa --help
Usage: rsa [options]
General options:
-help Display this summary
-check Verify key consistency
-* Any supported cipher
-engine val Use engine, possibly a hardware device
Input options:
-in val Input file
-inform format Input format (DER/PEM/P12/ENGINE
-pubin Expect a public key in input file
-RSAPublicKey_in Input is an RSAPublicKey
-passin val Input file pass phrase source
Output options:
-out outfile Output file
-outform format Output format, one of DER PEM PVK
-pubout Output a public key
-RSAPublicKey_out Output is an RSAPublicKey
-passout val Output file pass phrase source
-noout Don't print key out
-text Print the key in text
-modulus Print the RSA key modulus
-traditional Use traditional format for private keys
PVK options:
-pvk-strong Enable 'Strong' PVK encoding level (default)
-pvk-weak Enable 'Weak' PVK encoding level
-pvk-none Don't enforce PVK encoding
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
示例一：私钥文件内容查看
openssl rsa -in priv.pem -text
示例二：给秘钥添加/去除/修改对称加密的密码（注意：此处涉及密码输入的格式均为pass:pass_value）
// 为RSA密钥增加口令保护
openssl rsa -in RSA.pem -des3 -passout pass:123456 -out E_RSA.pem
// 为RSA密钥去除口令保护
openssl rsa -in E_RSA.pem -passin pass:123456 -out P_RSA.pem
// 修改加密算法为aes128，口令是123456
openssl rsa -in RSA.pem -passin pass:123456 -aes128 -passout pass:123456 -out E_RSA.pem
示例三：密钥格式转换
// 把pem格式转化成der格式，使用outform指定der格式
openssl rsa -in RSA.pem -passin pass:123456 -des -passout pass:123456 -outform der -out rsa.der
注意：DER用二进制编码的证书，PEM用ASCLL(BASE64)编码的证书，一般默认都是PEM格式。
示例四：公钥提取
openssl rsa -in private.pem -pubout -out public.pem
（3）openssl子命令rsautl能够使用RSA算法签名、验证身份、加密/解密数据。
$ openssl rsautl --help
The command rsautl was deprecated in version 3.0. Use 'pkeyutl' instead.
Usage: rsautl [options]
General options:
-help Display this summary
-sign Sign with private key
-verify Verify with public key
-encrypt Encrypt with public key
-decrypt Decrypt with private key
-engine val Use engine, possibly a hardware device
Input options:
-in infile Input file
-inkey val Input key
-keyform PEM|DER|ENGINE Private key format (ENGINE, other values ignored)
-pubin Input is an RSA public
-certin Input is a cert carrying an RSA public key
-rev Reverse the order of the input buffer
-passin val Input file pass phrase source
Output options:
-out outfile Output file
-raw Use no padding
-pkcs Use PKCS#1 v1.5 padding (default)
-x931 Use ANSI X9.31 padding
-oaep Use PKCS#1 OAEP
-asn1parse Run output through asn1parse; useful with -verify
-hexdump Hex dump output
Random state options:
-rand val Load the given file(s) into the random number generator
-writerand outfile Write random data to the specified file
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
示例一：使用公私钥加解密文件
// 用公钥加密文件
openssl rsautl -encrypt -in plain.text -inkey public.pem -out encrypt.text
// 用私钥解密文件
openssl rsautl -decrypt -in encrypt.text -inkey private.pem -out replain.text
示例二：使用公私钥签名/验签文件（此处的签名过程是针对文件的，故不涉及hash计算步骤）
// 用私钥签名
openssl rsautl -sign -in plain.text -inkey private.pem -out signed.text
// 用公钥验签
openssl rsautl -verify -in signed.text -pubin -inkey public.pem -out verify.text
信息摘要
信息摘要算法是将任意长度的数据转换成固定长度的字符串的过程，它通常用于验证数据的完整性和一致性，这类算法可通过命令 openssl list -digest-commands 具体查看。
（1）openssl子命令dgst为信息摘要计算工具。
$ openssl dgst --help
Usage: dgst [options] [file...]
General options:
-help Display this summary
-list List digests
-engine val Use engine e, possibly a hardware device
-engine_impl Also use engine given by -engine for digest operations
-passin val Input file pass phrase source
Output options:
-c Print the digest with separating colons
-r Print the digest in coreutils format
-out outfile Output to filename rather than stdout
-keyform format Key file format (ENGINE, other values ignored)
-hex Print as hex dump
-binary Print in binary form
-xoflen +int Output length for XOF algorithms
-d Print debug info
-debug Print debug info
Signing options:
-sign val Sign digest using private key
-verify val Verify a signature using public key
-prverify val Verify a signature using private key
-sigopt val Signature parameter in n:v form
-signature infile File with signature to verify
-hmac val Create hashed MAC with key
-mac val Create MAC (not necessarily HMAC)
-macopt val MAC algorithm parameters in n:v form or key
-* Any supported digest
-fips-fingerprint Compute HMAC with the key used in OpenSSL-FIPS fingerprint
Random state options:
-rand val Load the given file(s) into the random number generator
-writerand outfile Write random data to the specified file
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
Parameters:
file Files to digest (optional; default is stdin)
示例一：计算文件摘要
// 计算文件的md5值
openssl dgst -md5 test.txt
示例二：文件签名及验签（此处的签名是针对文件的hash值进行的，故一定会经历hash计算步骤）
// 使用private.pem私钥对文件plain.txt的哈希值进行签名并输出到test.text文件
openssl dgst -sign private.pem -out test.text plain.text
// 使用public.pem公钥对签名文件进行验签
openssl dgst -verify public.pem -signature test.text plain.text
数字证书
数字证书就是用一个权威的私钥（一般是CA根的私钥）对另一个第三方公司的公钥证书（即证书请求，包含公司信息、网址、自生成的公钥）进行签名来提升第三方公钥证书的可信度。
（1）openssl子命令req用于生成和处理证书请求文件及证书
$ openssl req --help
Usage: req [options]
General options:
-help Display this summary
-engine val Use engine, possibly a hardware device
-keygen_engine val Specify engine to be used for key generation operations
-in infile X.509 request input file (default stdin)
-inform PEM|DER Input format - DER or PEM
-verify Verify self-signature on the request
Certificate options:
-new New request
-config infile Request template file
-section val Config section to use (default "req")
-utf8 Input characters are UTF8 (default ASCII)
-nameopt val Certificate subject/issuer name printing options
-reqopt val Various request text options
-text Text form of request
-x509 Output an X.509 certificate structure instead of a cert request
-CA infile Issuer cert to use for signing a cert, implies -x509
-CAkey val Issuer private key to use with -CA; default is -CA arg
(Required by some CA's)
-subj val Set or modify subject of request or cert
-subject Print the subject of the output request or cert
-multivalue-rdn Deprecated; multi-valued RDNs support is always on.
-days +int Number of days cert is valid for
-set_serial val Serial number to use
-copy_extensions val copy extensions from request when using -x509
-addext val Additional cert extension key=value pair (may be given more than once)
-extensions val Cert extension section (override value in config file)
-reqexts val Request extension section (override value in config file)
-precert Add a poison extension to the generated cert (implies -new)
Keys and Signing options:
-key val Key for signing, and to include unless -in given
-keyform format Key file format (ENGINE, other values ignored)
-pubkey Output public key
-keyout outfile File to write private key to
-passin val Private key and certificate password source
-passout val Output file pass phrase source
-newkey val Generate new key with [<alg>:]<nbits> or <alg>[:<file>] or param:<file>
-pkeyopt val Public key options as opt:value
-sigopt val Signature parameter in n:v form
-vfyopt val Verification parameter in n:v form
-* Any supported digest
Output options:
-out outfile Output file
-outform PEM|DER Output format - DER or PEM
-batch Do not ask anything during request generation
-verbose Verbose output
-noenc Don't encrypt private keys
-nodes Don't encrypt private keys; deprecated
-noout Do not output REQ
-newhdr Output "NEW" in the header lines
-modulus RSA modulus
Random state options:
-rand val Load the given file(s) into the random number generator
-writerand outfile Write random data to the specified file
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
示例一：生成一个证书请求
// 使用已有的private.pem私钥去生成一个证书请求。（有个人信息问答环节）
openssl req -new -key private.pem -out request.csr
// 使用自动生成的RSA私钥去生成一个证书请求文件。（有个人信息问答环节）
openssl req -new -out request.csr
// 自动生成1024位且不加密并输出为RSA.pem的私钥，以及生成免问答的证书请求client.csr。
openssl req -new -newkey rsa:1024 -nodes -out client.csr -keyout RSA.pem -subj /C=AU/ST=Some-State/O=Internet
// 快速生成证书请求，跳过了私钥加密请求及个人信息问答环节。
openssl req -new -nodes -out request.csr -batch
注意：生成证书请求文件虽然一定需要RSA私钥的参与，但请求文件的内容中并未嵌入私钥的信息，只有从私钥中提取出来的公钥。
示例二：查看证书请求文件的内容信息
openssl req -in request.csr -text
示例三：从证书请求文件中提取公钥
openssl req -in client.csr -pubkey -noout >pub.pem
示例四：生成自签名证书（即根CA，可以拿来给其他证书请求文件做证书签名，即证书颁发）
// 首先生成一个私钥ca.key，然后根据私钥直接生成一个自签根证书ca.crt
openssl genrsa -out ca.key 2048
openssl req -new -x509 -days 365 -key ca.key -subj "/C=CN/ST=GD/L=SZ/O=Acme, Inc./CN=Acme Root CA" -out ca.crt
// 自动生成一个自签证书mycert.cer和它的私钥prvi.pem（会询问个人信息）
openssl req -x509 -nodes -days 365 -sha256 -newkey rsa:2048 -keyout prvi.pem -out mycert.cer
// 快捷验证生成的证书是否有效，网址 https://localhost:4433。（-cert所需的文件是一个私钥与证书的结合体，即 cat prvi.pem mycert.cer > mycert.pem）
openssl s_server -cert mycert.pem -www -accept 4433
（2）openssl子命令X509命令是一个多用途的证书工具，它可以显示证书信息、转换证书格式、签名证书请求以及改变证书的信任设置等。
$ openssl x509 --help
Usage: x509 [options]
General options:
-help Display this summary
-in infile Certificate input, or CSR input file with -req (default stdin)
-passin val Private key and cert file pass-phrase source
-new Generate a certificate from scratch
-x509toreq Output a certification request (rather than a certificate)
-req Input is a CSR file (rather than a certificate)
-copy_extensions val copy extensions when converting from CSR to x509 or vice versa
-inform format CSR input file format (DER or PEM) - default PEM
-vfyopt val CSR verification parameter in n:v form
-key val Key for signing, and to include unless using -force_pubkey
-signkey val Same as -key
-keyform PEM|DER|ENGINE Key input format (ENGINE, other values ignored)
-out outfile Output file - default stdout
-outform format Output format (DER or PEM) - default PEM
-nocert No cert output (except for requested printing)
-noout No output (except for requested printing)
Certificate printing options:
-text Print the certificate in text form
-dateopt val Datetime format used for printing. (rfc_822/iso_8601). Default is rfc_822.
-certopt val Various certificate text printing options
-fingerprint Print the certificate fingerprint
-alias Print certificate alias
-serial Print serial number value
-startdate Print the notBefore field
-enddate Print the notAfter field
-dates Print both notBefore and notAfter fields
-subject Print subject DN
-issuer Print issuer DN
-nameopt val Certificate subject/issuer name printing options
-email Print email address(es)
-hash Synonym for -subject_hash (for backward compat)
-subject_hash Print subject hash value
-subject_hash_old Print old-style (MD5) subject hash value
-issuer_hash Print issuer hash value
-issuer_hash_old Print old-style (MD5) issuer hash value
-ext val Restrict which X.509 extensions to print and/or copy
-ocspid Print OCSP hash values for the subject name and public key
-ocsp_uri Print OCSP Responder URL(s)
-purpose Print out certificate purposes
-pubkey Print the public key in PEM format
-modulus Print the RSA key modulus
Certificate checking options:
-checkend intmax Check whether cert expires in the next arg seconds
Exit 1 (failure) if so, 0 if not
-checkhost val Check certificate matches host
-checkemail val Check certificate matches email
-checkip val Check certificate matches ipaddr
Certificate output options:
-set_serial val Serial number to use, overrides -CAserial
-next_serial Increment current certificate serial number
-days int Number of days until newly generated certificate expires - default 30
-preserve_dates Preserve existing validity dates
-subj val Set or override certificate subject (and issuer)
-force_pubkey infile Place the given key in new certificate
-clrext Do not take over any extensions from the source certificate or request
-extfile infile Config file with X509V3 extensions to add
-extensions val Section of extfile to use - default: unnamed section
-sigopt val Signature parameter, in n:v form
-badsig Corrupt last byte of certificate signature (for test)
-* Any supported digest, used for signing and printing
Micro-CA options:
-CA infile Use the given CA certificate, conflicts with -key
-CAform PEM|DER CA cert format (PEM/DER/P12); has no effect
-CAkey val The corresponding CA key; default is -CA arg
-CAkeyform PEM|DER|ENGINE CA key format (ENGINE, other values ignored)
-CAserial val File that keeps track of CA-generated serial number
-CAcreateserial Create CA serial number file if it does not exist
Certificate trust output options:
-trustout Mark certificate PEM output as trusted
-setalias val Set certificate alias (nickname)
-clrtrust Clear all trusted purposes
-addtrust val Trust certificate for a given purpose
-clrreject Clears all the prohibited or rejected uses of the certificate
-addreject val Reject certificate for a given purpose
Random state options:
-rand val Load the given file(s) into the random number generator
-writerand outfile Write random data to the specified file
-engine val Use engine, possibly a hardware device
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
示例一：使用自签根证书为证书请求文件签名
// 生成请求文件server.csr，然后使用自签名证书为其签名
openssl req -newkey rsa:2048 -nodes -keyout server.key -subj "/C=CN/ST=GD/L=SZ/O=Acme, Inc./CN=localhost" -out server.csr
openssl x509 -sha256 -req -days 365 -in server.csr -CA ca.crt -CAkey ca.key -CAcreateserial -out server.crt
杂项
（1）openssl子命令rand用于生成伪随机数
$ openssl rand --help
Usage: rand [options] num
General options:
-help Display this summary
-engine val Use engine, possibly a hardware device
Output options:
-out outfile Output file
-base64 Base64 encode output
-hex Hex encode output
Random state options:
-rand val Load the given file(s) into the random number generator
-writerand outfile Write random data to the specified file
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
Parameters:
num Number of bytes to generate
示例一：生成随机值
// 生成3个字节的随机数
openssl rand -hex 3
注意：由于生成是随机的字节，因此如果不通过-base64或-hex编码的话输出会显示乱码。
（2）openssl子命令passwd用于生成Linux用户账户的密码格式
$ openssl passwd --help
Usage: passwd [options] [password]
General options:
-help Display this summary
Input options:
-in infile Read passwords from file
-noverify Never verify when reading password from terminal
-stdin Read passwords from stdin
Output options:
-quiet No warnings
-table Format output as table
-reverse Switch table columns
Cryptographic options:
-salt val Use provided salt
-6 SHA512-based password algorithm
-5 SHA256-based password algorithm
-apr1 MD5-based password algorithm, Apache variant
-1 MD5-based password algorithm
-aixmd5 AIX MD5-based password algorithm
Random state options:
-rand val Load the given file(s) into the random number generator
-writerand outfile Write random data to the specified file
Provider options:
-provider-path val Provider load path (must be before 'provider' argument if required)
-provider val Provider to load (can be specified multiple times)
-propquery val Property query used when fetching algorithms
Parameters:
password Password text to digest (optional)
示例一：对明文密码进行加密处理
// 基本用法
openssl passwd 12345
// 使用盐值进行密码加密（默认盐值不固定，导致同一条命令每次执行都会产生不同的结果）
openssl passwd -salt 'z' 12345