openssl - OpenSSL command line tool
openssl command [ command_opts ... ] [ command_args ... ]
openssl list -standard-commands | -digest-commands | -cipher-commands | -cipher-algorithms | -digest-algorithms | -mac-algorithms | -public-key-algorithms
openssl no-XXX [ arbitrary options ]
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 and Message Authentication Codes o Encryption and Decryption with Ciphers o SSL/TLS Client and Server Tests o Handling of S/MIME signed or encrypted mail o Timestamp requests, generation and verification
The openssl program provides a rich variety of sub-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).
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 options -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.
The list parameters -cipher-algorithms, -digest-algorithms, and -mac-algorithms list all cipher, message digest, and message authentication code 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.)
Parse an ASN.1 sequence.
Certificate Authority (CA) Management.
Cipher Suite Description Determination.
CMS (Cryptographic Message Syntax) utility.
Certificate Revocation List (CRL) Management.
CRL to PKCS#7 Conversion.
Message Digest calculation. MAC calculations are superseded by openssl-mac(1).
Diffie-Hellman Parameter Management. Obsoleted by openssl-dhparam(1).
DSA Data Management.
EC (Elliptic curve) key processing.
EC parameter manipulation and generation.
Encoding with Ciphers.
Engine (loadable module) information and manipulation.
Error Number to Error String Conversion.
Generation of Diffie-Hellman Parameters. Obsoleted by openssl-dhparam(1).
Generation of Private Key or Parameters.
Generation of RSA Private Key. Superseded by openssl-genpkey(1).
Display diverse information built into the OpenSSL libraries.
Key Derivation Functions.
Message Authentication Code Calculation.
Create or examine a Netscape certificate sequence.
Online Certificate Status Protocol utility.
Generation of hashed passwords.
PKCS#12 Data Management.
PKCS#7 Data Management.
PKCS#8 format private key conversion tool.
Public and private key management.
Public key algorithm parameter management.
Public key algorithm cryptographic operation utility.
Compute prime numbers.
Generate pseudo-random bytes.
Create symbolic links to certificate and CRL files named by the hash values.
PKCS#10 X.509 Certificate Signing Request (CSR) Management.
RSA key management.
RSA utility for signing, verification, encryption, and decryption. Superseded by openssl-pkeyutl(1).
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.
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.
SSL Connection Timer.
SSL Session Data Management.
S/MIME mail processing.
Algorithm Speed Measurement.
SPKAC printing and generating utility.
Maintain SRP password file.
Utility to list and display certificates, keys, CRLs, etc.
Time Stamping Authority tool (client/server).
X.509 Certificate Verification.
OpenSSL Version Information.
X.509 Certificate Data Management.
Message Digest Commands
SHA-2 224 Digest
SHA-2 256 Digest
SHA-2 384 Digest
SHA-2 512 Digest
SHA-3 224 Digest
SHA-3 256 Digest
SHA-3 384 Digest
SHA-3 512 Digest
SHA-3 SHAKE128 Digest
SHA-3 SHAKE256 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 openssl-enc(1) for more information and command usage.
- aes128, aes-128-cbc, aes-128-cfb, aes-128-ctr, aes-128-ecb, aes-128-ofb
- aes192, aes-192-cbc, aes-192-cfb, aes-192-ctr, aes-192-ecb, aes-192-ofb
- aes256, aes-256-cbc, aes-256-cfb, aes-256-ctr, aes-256-ecb, aes-256-ofb
- aria128, aria-128-cbc, aria-128-cfb, aria-128-ctr, aria-128-ecb, aria-128-ofb
- aria192, aria-192-cbc, aria-192-cfb, aria-192-ctr, aria-192-ecb, aria-192-ofb
- aria256, aria-256-cbc, aria-256-cfb, aria-256-ctr, aria-256-ecb, aria-256-ofb
- bf, bf-cbc, bf-cfb, bf-ecb, bf-ofb
- camellia128, camellia-128-cbc, camellia-128-cfb, camellia-128-ctr, camellia-128-ecb, camellia-128-ofb
- camellia192, camellia-192-cbc, camellia-192-cfb, camellia-192-ctr, camellia-192-ecb, camellia-192-ofb
- camellia256, camellia-256-cbc, camellia-256-cfb, camellia-256-ctr, camellia-256-ecb, camellia-256-ofb
- cast, cast-cbc
- cast5-cbc, cast5-cfb, cast5-ecb, cast5-ofb
- des, des-cbc, des-cfb, des-ecb, des-ede, des-ede-cbc, des-ede-cfb, des-ede-ofb, des-ofb
- des3, desx, des-ede3, des-ede3-cbc, des-ede3-cfb, des-ede3-ofb
- idea, idea-cbc, idea-cfb, idea-ecb, idea-ofb
- rc2, rc2-cbc, rc2-cfb, rc2-ecb, rc2-ofb
- rc5, rc5-cbc, rc5-cfb, rc5-ecb, rc5-ofb
- seed, seed-cbc, seed-cfb, seed-ecb, seed-ofb
- sm4, sm4-cbc, sm4-cfb, sm4-ctr, sm4-ecb, sm4-ofb
Details of which options are available depend on the specific command. This section describes some common options with common behavior.
Provides a terse summary of all options. If an option takes an argument, the "type" of argument is also given.
This terminates the list of options. It is mostly useful if any filename parameters start with a minus sign:
openssl verify [flags...] -- -cert1.pem...
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.
Note that character encoding may be relevant, please see passphrase-encoding(7).
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.
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.
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.
Read the password from the file descriptor number. This can be used to send the data via a pipe for example.
Read the password from standard input.
Trusted Certificate Options
Part of validating a certificate includes verifying that the chain of CA's can be traced up to an existing trusted root. The following options specify how to list the trusted roots, also known as trust anchors. A collection of trusted roots is called a trust store.
Note that OpenSSL does not provide a default set of trust anchors. Many Linux distributions include a system default and configure OpenSSL to point to that. Mozilla maintains an influential trust store that can be found at https://www.mozilla.org/en-US/about/governance/policies/security-group/certs/.
- -CAfile file
Load the specified file which contains one or more PEM-format certificates of CA's that are trusted.
Do not load the default file of trusted certificates.
- -CApath dir
Use the specified directory as a list of trust certificates. That is, files should be named with the hash of the X.509 SubjectName of each certificate. This is so that the library can extract the IssuerName, hash it, and directly lookup the file to get the issuer certificate. See openssl-rehash(1) for information on creating this type of directory.
Do not use the default directory of trusted certificates.
Random State Options
Prior to OpenSSL 3.0, it was common for applications to store information about the state of the random-number generator in a file that was loaded at startup and rewritten upon exit. On modern operating systems, this is generally no longer necessary as OpenSSL will seed itself from the appropriate CPU flags, device files, and so on. These flags are still supported for special platforms or circumstances that might require them.
It is generally an error to use the same seed file more than once and every use of -rand should be paired with -writerand.
- -rand files
A file or files containing random data used to seed the random number generator. Multiple files can be specified separated by an OS-dependent character. The separator is
,for OpenVMS, and
:for all others. Another way to specify multiple files is to repeat this flag with different filenames.
- -writerand file
Writes the seed data to the specified file upon exit. This file can be used in a subsequent command invocation.
Enable tracing output of OpenSSL library, by name. This output will only make sense if you know OpenSSL internals well. Also, it might not give you any output at all, depending on how OpenSSL was built.
The value is a comma separated list of names, with the following available:
The tracing functionality.
The function that is used by RSA, DSA (etc) code to select registered ENGINEs, cache defaults and functional references (etc), will generate debugging summaries.
Reference counts in the ENGINE structure will be monitored with a line of generated for each change.
PKCS#5 v2 keygen.
PKCS#12 key generation.
Generates the complete policy tree at various point during X.509 v3 policy evaluation.
openssl-asn1parse(1), openssl-ca(1), openssl-ciphers(1), openssl-cms(1), openssl-crl(1), openssl-crl2pkcs7(1), openssl-dgst(1), openssl-dhparam(1), openssl-dsa(1), openssl-dsaparam(1), openssl-ec(1), openssl-ecparam(1), openssl-enc(1), openssl-engine(1), openssl-errstr(1), openssl-gendsa(1), openssl-genpkey(1), openssl-genrsa(1), openssl-kdf(1), openssl-mac(1), openssl-nseq(1), openssl-ocsp(1), openssl-passwd(1), openssl-pkcs12(1), openssl-pkcs7(1), openssl-pkcs8(1), openssl-pkey(1), openssl-pkeyparam(1), openssl-pkeyutl(1), openssl-prime(1), openssl-rand(1), openssl-rehash(1), openssl-req(1), openssl-rsa(1), openssl-rsautl(1), openssl-s_client(1), openssl-s_server(1), openssl-s_time(1), openssl-sess_id(1), openssl-smime(1), openssl-speed(1), openssl-spkac(1), openssl-srp(1), openssl-storeutl(1), openssl-ts(1), openssl-verify(1), openssl-version(1), openssl-x509(1), config(5), crypto(7), ssl(7), x509v3_config(5)
The list -XXX-algorithms options were added in OpenSSL 1.0.0; For notes on the availability of other commands, see their individual manual pages.
Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (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.