openssl - OpenSSL command line program
openssl command [ options ... ] [
parameters ... ]
openssl no-XXX [ options ]
openssl -help | -version
OpenSSL is a cryptography toolkit implementing the Secure Sockets
Layer (SSL) and Transport Layer Security (TLS) network protocols and related
cryptography standards required by them.
The openssl program is a command line program 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 commands
(command in the "SYNOPSIS" above). Each command can have
many options and argument parameters, shown above as options and
parameters.
Detailed documentation and use cases for most standard subcommands
are available (e.g., openssl-x509(1)). The subcommand
openssl-list(1) may be used to list subcommands.
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.)
Many commands use an external configuration file for some or all
of their arguments and have a -config option to specify that file.
The default name of the file is openssl.cnf in the default
certificate storage area, which can be determined from the
openssl-version(1) command using the -d or -a option.
The environment variable OPENSSL_CONF can be used to specify a
different file location or to disable loading a configuration (using the
empty string).
Among others, the configuration file can be used to load modules
and to specify parameters for generating certificates and random numbers.
See config(5) for details.
- asn1parse
- Parse an ASN.1 sequence.
- ca
- Certificate Authority (CA) Management.
- ciphers
- Cipher Suite Description Determination.
- cms
- CMS (Cryptographic Message Syntax) command.
- crl
- Certificate Revocation List (CRL) Management.
- crl2pkcs7
- CRL to PKCS#7 Conversion.
- dgst
- Message Digest calculation. MAC calculations are superseded by
openssl-mac(1).
- dhparam
- Generation and Management of Diffie-Hellman Parameters. Superseded by
openssl-genpkey(1) and openssl-pkeyparam(1).
- dsa
- DSA Data Management.
- dsaparam
- DSA Parameter Generation and Management. Superseded by
openssl-genpkey(1) and openssl-pkeyparam(1).
- ec
- EC (Elliptic curve) key processing.
- ecparam
- EC parameter manipulation and generation.
- enc
- Encryption, decryption, and encoding.
- engine
- Engine (loadable module) information and manipulation.
- errstr
- Error Number to Error String Conversion.
- fipsinstall
- FIPS configuration installation.
- gendsa
- Generation of DSA Private Key from Parameters. Superseded by
openssl-genpkey(1) and openssl-pkey(1).
- genpkey
- Generation of Private Key or Parameters.
- genrsa
- Generation of RSA Private Key. Superseded by
openssl-genpkey(1).
- help
- Display information about a command's options.
- info
- Display diverse information built into the OpenSSL libraries.
- kdf
- Key Derivation Functions.
- list
- List algorithms and features.
- mac
- Message Authentication Code Calculation.
- nseq
- Create or examine a Netscape certificate sequence.
- ocsp
- Online Certificate Status Protocol command.
- passwd
- Generation of hashed passwords.
- pkcs12
- PKCS#12 Data Management.
- pkcs7
- PKCS#7 Data Management.
- pkcs8
- PKCS#8 format private key conversion command.
- pkey
- Public and private key management.
- pkeyparam
- Public key algorithm parameter management.
- pkeyutl
- Public key algorithm cryptographic operation command.
- prime
- Compute prime numbers.
- rand
- Generate pseudo-random bytes.
- rehash
- Create symbolic links to certificate and CRL files named by the hash
values.
- req
- PKCS#10 X.509 Certificate Signing Request (CSR) Management.
- rsa
- RSA key management.
- rsautl
- RSA command for signing, verification, encryption, and decryption.
Superseded by openssl-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 command.
- srp
- Maintain SRP password file. This command is deprecated.
- storeutl
- Command to list and display certificates, keys, CRLs, etc.
- ts
- Time Stamping Authority command.
- verify
- X.509 Certificate Verification. See also the
openssl-verification-options(1) manual page.
- version
- OpenSSL Version Information.
- x509
- X.509 Certificate Data Management.
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.
- aes128,
aes-128-cbc, aes-128-cfb, aes-128-ctr,
aes-128-ecb, aes-128-ofb
- AES-128 Cipher
- aes192,
aes-192-cbc, aes-192-cfb, aes-192-ctr,
aes-192-ecb, aes-192-ofb
- AES-192 Cipher
- aes256,
aes-256-cbc, aes-256-cfb, aes-256-ctr,
aes-256-ecb, aes-256-ofb
- AES-256 Cipher
- aria128,
aria-128-cbc, aria-128-cfb, aria-128-ctr,
aria-128-ecb, aria-128-ofb
- Aria-128 Cipher
- aria192,
aria-192-cbc, aria-192-cfb, aria-192-ctr,
aria-192-ecb, aria-192-ofb
- Aria-192 Cipher
- aria256,
aria-256-cbc, aria-256-cfb, aria-256-ctr,
aria-256-ecb, aria-256-ofb
- Aria-256 Cipher
- base64
- Base64 Encoding
- bf, bf-cbc,
bf-cfb, bf-ecb, bf-ofb
- Blowfish Cipher
- camellia128,
camellia-128-cbc, camellia-128-cfb, camellia-128-ctr,
camellia-128-ecb, camellia-128-ofb
- Camellia-128 Cipher
- camellia192,
camellia-192-cbc, camellia-192-cfb, camellia-192-ctr,
camellia-192-ecb, camellia-192-ofb
- Camellia-192 Cipher
- camellia256,
camellia-256-cbc, camellia-256-cfb, camellia-256-ctr,
camellia-256-ecb, camellia-256-ofb
- Camellia-256 Cipher
- cast,
cast-cbc
- CAST Cipher
- cast5-cbc,
cast5-cfb, cast5-ecb, cast5-ofb
- CAST5 Cipher
- chacha20
- Chacha20 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
- seed, seed-cbc,
seed-cfb, seed-ecb, seed-ofb
- SEED Cipher
- sm4, sm4-cbc,
sm4-cfb, sm4-ctr, sm4-ecb, sm4-ofb
- SM4 Cipher
Details of which options are available depend on the specific
command. This section describes some common options with common
behavior.
These options can be specified without a command specified to get
help or version information.
- -help
- Provides a terse summary of all options. For more detailed information,
each command supports a -help option. Accepts --help as
well.
- -version
- Provides a terse summary of the openssl program version. For more
detailed information see openssl-version(1). Accepts
--version as well.
- -help
- 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...
See openssl-format-options(1) for manual page.
See the openssl-passphrase-options(1) manual page.
Prior to OpenSSL 1.1.1, 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 a
trusted entropy source provided by the operating system. 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
MS-Windows, "," 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.
See the openssl-verification-options(1) manual page.
See the openssl-namedisplay-options(1) manual page.
Several commands use SSL, TLS, or DTLS. By default, the commands
use TLS and clients will offer the lowest and highest protocol version they
support, and servers will pick the highest version that the client offers
that is also supported by the server.
The options below can be used to limit which protocol versions are
used, and whether TCP (SSL and TLS) or UDP (DTLS) is used. Note that not all
protocols and flags may be available, depending on how OpenSSL was
built.
- -ssl3, -tls1,
-tls1_1, -tls1_2, -tls1_3, -no_ssl3,
-no_tls1, -no_tls1_1, -no_tls1_2,
-no_tls1_3
- These options require or disable the use of the specified SSL or TLS
protocols. When a specific TLS version is required, only that version will
be offered or accepted. Only one specific protocol can be given and it
cannot be combined with any of the no_ options. The no_*
options do not work with s_time and ciphers commands but
work with s_client and s_server commands.
- -dtls, -dtls1,
-dtls1_2
- These options specify to use DTLS instead of TLS. With -dtls,
clients will negotiate any supported DTLS protocol version. Use the
-dtls1 or -dtls1_2 options to support only DTLS1.0 or
DTLS1.2, respectively.
- -engine
id
- Load the engine identified by id and use all the methods it
implements (algorithms, key storage, etc.), unless specified otherwise in
the command-specific documentation or it is configured to do so, as
described in "Engine Configuration" in config(5).
The engine will be used for key ids specified with -key
and similar options when an option like -keyform engine is
given.
A special case is the
"loader_attic" engine, which is meant
just for internal OpenSSL testing purposes and supports loading keys,
parameters, certificates, and CRLs from files. When this engine is used,
files with such credentials are read via this engine. Using the
"file:" schema is optional; a plain
file (path) name will do.
Options specifying keys, like -key and similar, can use the
generic OpenSSL engine key loading URI scheme
"org.openssl.engine:" to retrieve private
keys and public keys. The URI syntax is as follows, in simplified form:
org.openssl.engine:{engineid}:{keyid}
Where "{engineid}" is the
identity/name of the engine, and "{keyid}"
is a key identifier that's acceptable by that engine. For example, when
using an engine that interfaces against a PKCS#11 implementation, the
generic key URI would be something like this (this happens to be an example
for the PKCS#11 engine that's part of OpenSC):
-key org.openssl.engine:pkcs11:label_some-private-key
As a third possibility, for engines and providers that have
implemented their own OSSL_STORE_LOADER(3),
"org.openssl.engine:" should not be
necessary. For a PKCS#11 implementation that has implemented such a loader,
the PKCS#11 URI as defined in RFC 7512 should be possible to use
directly:
-key pkcs11:object=some-private-key;pin-value=1234
- -provider
name
- Load and initialize the provider identified by name. The
name can be also a path to the provider module. In that case the
provider name will be the specified path and not just the provider module
name. Interpretation of relative paths is platform specific. The
configured "MODULESDIR" path, OPENSSL_MODULES environment
variable, or the path specified by -provider-path is prepended to
relative paths. See provider(7) for a more detailed
description.
- -provider-path
path
- Specifies the search path that is to be used for looking for providers.
Equivalently, the OPENSSL_MODULES environment variable may be
set.
- -propquery
propq
- Specifies the property query clause to be used when fetching
algorithms from the loaded providers. See property(7) for a more
detailed description.
The OpenSSL library can be take some configuration parameters from
the environment. Some of these variables are listed below. For information
about specific commands, see openssl-engine(1),
openssl-rehash(1), and tsget(1).
For information about the use of environment variables in
configuration, see "ENVIRONMENT" in config(5).
For information about querying or specifying CPU architecture
flags, see OPENSSL_ia32cap(3), and OPENSSL_s390xcap(3).
For information about all environment variables used by the
OpenSSL libraries, see openssl-env(7).
- OPENSSL_TRACE=name[,...]
- 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 if OpenSSL was built without tracing support.
The value is a comma separated list of names, with the
following available:
- TRACE
- Traces the OpenSSL trace API itself.
- INIT
- Traces OpenSSL library initialization and cleanup.
- TLS
- Traces the TLS/SSL protocol.
- TLS_CIPHER
- Traces the ciphers used by the TLS/SSL protocol.
- CONF
- Show details about provider and engine configuration.
- ENGINE_TABLE
- The function that is used by RSA, DSA (etc) code to select registered
ENGINEs, cache defaults and functional references (etc), will generate
debugging summaries.
- ENGINE_REF_COUNT
- Reference counts in the ENGINE structure will be monitored with a line of
generated for each change.
- PKCS5V2
- Traces PKCS#5 v2 key generation.
- PKCS12_KEYGEN
- Traces PKCS#12 key generation.
- PKCS12_DECRYPT
- Traces PKCS#12 decryption.
- X509V3_POLICY
- Generates the complete policy tree at various points during X.509 v3
policy evaluation.
- BN_CTX
- Traces BIGNUM context operations.
- CMP
- Traces CMP client and server activity.
- STORE
- Traces STORE operations.
- DECODER
- Traces decoder operations.
- ENCODER
- Traces encoder operations.
- REF_COUNT
- Traces decrementing certain ASN.1 structure references.
- HTTP
- Traces the HTTP client and server, such as messages being sent and
received.
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-list(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), openssl-env(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.
The -issuer_checks option is deprecated as of OpenSSL 1.1.0
and is silently ignored.
The -xcertform and -xkeyform options are obsolete
since OpenSSL 3.0 and have no effect.
The interactive mode, which could be invoked by running
"openssl" with no further arguments, was
removed in OpenSSL 3.0, and running that program with no arguments is now
equivalent to "openssl help".
Copyright 2000-2023 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>.