How to use the command openssl on centos 7

[root@xtwj89 ~]# man openssl |cat
OPENSSL(1)                                                                                                       OpenSSL                                                                                                      OPENSSL(1)



NAME
       openssl - OpenSSL command line tool

SYNOPSIS
       openssl command [ command_opts ] [ command_args ]

       openssl [ list-standard-commands | list-message-digest-commands | list-cipher-commands | list-cipher-algorithms | list-message-digest-algorithms | list-public-key-algorithms]

       openssl no-XXX [ arbitrary options ]

DESCRIPTION
       OpenSSL is a cryptography toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) network protocols and related cryptography standards required by them.

       The openssl program is a command line tool for using the various cryptography functions of OpenSSL's crypto library from the shell.  It can be used for

        o  Creation and management of private keys, public keys and parameters
        o  Public key cryptographic operations
        o  Creation of X.509 certificates, CSRs and CRLs
        o  Calculation of Message Digests
        o  Encryption and Decryption with Ciphers
        o  SSL/TLS Client and Server Tests
        o  Handling of S/MIME signed or encrypted mail
        o  Time Stamp requests, generation and verification

COMMAND SUMMARY
       The openssl program provides a rich variety of commands (command in the SYNOPSIS above), each of which often has a wealth of options and arguments (command_opts and command_args in the SYNOPSIS).

       The pseudo-commands list-standard-commands, list-message-digest-commands, and list-cipher-commands output a list (one entry per line) of the names of all standard commands, message digest commands, or cipher commands,
       respectively, that are available in the present openssl utility.

       The pseudo-commands list-cipher-algorithms and list-message-digest-algorithms list all cipher and message digest names, one entry per line. Aliases are listed as:

        from => to

       The pseudo-command list-public-key-algorithms lists all supported public key algorithms.

       The pseudo-command no-XXX tests whether a command of the specified name is available.  If no command named XXX exists, it returns 0 (success) and prints no-XXX; otherwise it returns 1 and prints XXX.  In both cases, the
       output goes to stdout and nothing is printed to stderr.  Additional command line arguments are always ignored.  Since for each cipher there is a command of the same name, this provides an easy way for shell scripts to test
       for the availability of ciphers in the openssl program.  (no-XXX is not able to detect pseudo-commands such as quit, list-...-commands, or no-XXX itself.)

   STANDARD COMMANDS
       asn1parse Parse an ASN.1 sequence.

       ca        Certificate Authority (CA) Management.

       ciphers   Cipher Suite Description Determination.

       cms       CMS (Cryptographic Message Syntax) utility

       crl       Certificate Revocation List (CRL) Management.

       crl2pkcs7 CRL to PKCS#7 Conversion.

       dgst      Message Digest Calculation.

       dh        Diffie-Hellman Parameter Management.  Obsoleted by dhparam.

       dhparam   Generation and Management of Diffie-Hellman Parameters. Superseded by genpkey and pkeyparam

       dsa       DSA Data Management.

       dsaparam  DSA Parameter Generation and Management. Superseded by genpkey and pkeyparam

       ec        EC (Elliptic curve) key processing

       ecparam   EC parameter manipulation and generation

       enc       Encoding with Ciphers.

       engine    Engine (loadble module) information and manipulation.

       errstr    Error Number to Error String Conversion.

       gendh     Generation of Diffie-Hellman Parameters.  Obsoleted by dhparam.

       gendsa    Generation of DSA Private Key from Parameters. Superseded by genpkey and pkey

       genpkey   Generation of Private Key or Parameters.

       genrsa    Generation of RSA Private Key. Superceded by genpkey.

       nseq      Create or examine a netscape certificate sequence

       ocsp      Online Certificate Status Protocol utility.

       passwd    Generation of hashed passwords.

       pkcs12    PKCS#12 Data Management.

       pkcs7     PKCS#7 Data Management.

       pkey      Public and private key management.

       pkeyparam Public key algorithm parameter management.

       pkeyutl   Public key algorithm cryptographic operation utility.

       rand      Generate pseudo-random bytes.

       req       PKCS#10 X.509 Certificate Signing Request (CSR) Management.

       rsa       RSA key management.

       rsautl    RSA utility for signing, verification, encryption, and decryption. Superseded by  pkeyutl

       s_client  This implements a generic SSL/TLS client which can establish a transparent connection to a remote server speaking SSL/TLS. It's intended for testing purposes only and provides only rudimentary interface
                 functionality but internally uses mostly all functionality of the OpenSSL ssl library.

       s_server  This implements a generic SSL/TLS server which accepts connections from remote clients speaking SSL/TLS. It's intended for testing purposes only and provides only rudimentary interface functionality but internally
                 uses mostly all functionality of the OpenSSL ssl library.  It provides both an own command line oriented protocol for testing SSL functions and a simple HTTP response facility to emulate an SSL/TLS-aware webserver.

       s_time    SSL Connection Timer.

       sess_id   SSL Session Data Management.

       smime     S/MIME mail processing.

       speed     Algorithm Speed Measurement.

       spkac     SPKAC printing and generating utility

       ts        Time Stamping Authority tool (client/server)

       verify    X.509 Certificate Verification.

       version   OpenSSL Version Information.

       x509      X.509 Certificate Data Management.

   MESSAGE DIGEST COMMANDS
       md2       MD2 Digest

       md5       MD5 Digest

       mdc2      MDC2 Digest

       rmd160    RMD-160 Digest

       sha       SHA Digest

       sha1      SHA-1 Digest

       sha224    SHA-224 Digest

       sha256    SHA-256 Digest

       sha384    SHA-384 Digest

       sha512    SHA-512 Digest

   ENCODING AND CIPHER COMMANDS
       base64    Base64 Encoding

       bf bf-cbc bf-cfb bf-ecb bf-ofb
                 Blowfish Cipher

       cast cast-cbc
                 CAST Cipher

       cast5-cbc cast5-cfb cast5-ecb cast5-ofb
                 CAST5 Cipher

       des des-cbc des-cfb des-ecb des-ede des-ede-cbc des-ede-cfb des-ede-ofb des-ofb
                 DES Cipher

       des3 desx des-ede3 des-ede3-cbc des-ede3-cfb des-ede3-ofb
                 Triple-DES Cipher

       idea idea-cbc idea-cfb idea-ecb idea-ofb
                 IDEA Cipher

       rc2 rc2-cbc rc2-cfb rc2-ecb rc2-ofb
                 RC2 Cipher

       rc4       RC4 Cipher

       rc5 rc5-cbc rc5-cfb rc5-ecb rc5-ofb
                 RC5 Cipher

PASS PHRASE ARGUMENTS
       Several commands accept password arguments, typically using -passin and -passout for input and output passwords respectively. These allow the password to be obtained from a variety of sources. Both of these options take a
       single argument whose format is described below. If no password argument is given and a password is required then the user is prompted to enter one: this will typically be read from the current terminal with echoing turned
       off.

       pass:password
                 the actual password is password. Since the password is visible to utilities (like 'ps' under Unix) this form should only be used where security is not important.

       env:var   obtain the password from the environment variable var. Since the environment of other processes is visible on certain platforms (e.g. ps under certain Unix OSes) this option should be used with caution.

       file:pathname
                 the first line of pathname is the password. If the same pathname argument is supplied to -passin and -passout arguments then the first line will be used for the input password and the next line for the output
                 password. pathname need not refer to a regular file: it could for example refer to a device or named pipe.

       fd:number read the password from the file descriptor number. This can be used to send the data via a pipe for example.

       stdin     read the password from standard input.

SEE ALSO
       asn1parse(1), ca(1), config(5), crl(1), crl2pkcs7(1), dgst(1), dhparam(1), dsa(1), dsaparam(1), enc(1), gendsa(1), genpkey(1), genrsa(1), nseq(1), openssl(1), sslpasswd(1), pkcs12(1), pkcs7(1), pkcs8(1), sslrand(1), req(1),
       rsa(1), rsautl(1), s_client(1), s_server(1), s_time(1), smime(1), spkac(1), verify(1), version(1), x509(1), crypto(3), ssl(3), x509v3_config(5)

HISTORY
       The openssl(1) document appeared in OpenSSL 0.9.2.  The list-XXX-commands pseudo-commands were added in OpenSSL 0.9.3; The list-XXX-algorithms pseudo-commands were added in OpenSSL 1.0.0; the no-XXX pseudo-commands were added
       in OpenSSL 0.9.5a.  For notes on the availability of other commands, see their individual manual pages.



1.0.2k                                                                                                         2019-08-09                                                                                                     OPENSSL(1)
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