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).
Detailed documentation and use cases for most standard subcommands are available (e.g., x509(1) or openssl-x509(1)).
Many commands use an external configuration file for some or all of their arguments and have a -config option to specify that file. The environment variable OPENSSL_CONF can be used to specify the location of the file. If the environment variable is not specified, then the file is named openssl.cnf in the default certificate storage area, whose value depends on the configuration flags specified when the OpenSSL was built.
The list parameters standard-commands, digest-commands, and 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 list parameters cipher-algorithms and digest-algorithms list all cipher and message digest names, one entry per line. Aliases are listed as:
from => to
The list parameter public-key-algorithms lists all supported public key algorithms.
The 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, 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(1).
dhparam
Generation and Management of Diffie-Hellman Parameters. Superseded by genpkey(1) and pkeyparam(1).
RSA utility for signing, verification, encryption, and decryption. Superseded by pkeyutl(1).
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.
srp
Maintain SRP password file.
storeutl
Utility to list and display certificates, keys, CRLs, etc.
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
blake2b512
BLAKE2b-512 Digest
blake2s256
BLAKE2s-256 Digest
md2
MD2 Digest
md4
MD4 Digest
md5
MD5 Digest
mdc2
MDC2 Digest
rmd160
RMD-160 Digest
sha1
SHA-1 Digest
sha224
SHA-2 224 Digest
sha256
SHA-2 256 Digest
sha384
SHA-2 384 Digest
sha512
SHA-2 512 Digest
sha3-224
SHA-3 224 Digest
sha3-256
SHA-3 256 Digest
sha3-384
SHA-3 384 Digest
sha3-512
SHA-3 512 Digest
shake128
SHA-3 SHAKE128 Digest
shake256
SHA-3 SHAKE256 Digest
sm3
SM3 Digest
Encoding and Cipher Commands
The following aliases provide convenient access to the most used encodings and ciphers.
Depending on how OpenSSL was configured and built, not all ciphers listed here may be present. See enc(1) for more information and command usage.
Details of which options are available depend on the specific command. This section describes some common options with common behavior.
Common Options
-help
Provides a terse summary of all options.
Pass Phrase Options
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.
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.
The list-XXX-algorithms pseudo-commands were added in OpenSSL 1.0.0; For notes on the availability of other commands, see their individual manual pages.
COPYRIGHT
Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at https://www.openssl.org/source/license.html.