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openssl - OpenSSL command line tool


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 ]


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


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.)


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.
Diffie-Hellman Parameter Management. Obsoleted by dhparam.
Generation and Management of Diffie-Hellman Parameters. Superseded by genpkey and pkeyparam
DSA Data Management.
DSA Parameter Generation and Management. Superseded by genpkey and pkeyparam
EC (Elliptic curve) key processing
EC parameter manipulation and generation
Encoding with Ciphers.
Engine (loadble module) information and manipulation.
Error Number to Error String Conversion.
Generation of Diffie-Hellman Parameters. Obsoleted by dhparam.
Generation of DSA Private Key from Parameters. Superseded by genpkey and pkey
Generation of Private Key or Parameters.
Generation of RSA Private Key. Superceded by genpkey.
Create or examine a netscape certificate sequence
Online Certificate Status Protocol utility.
Generation of hashed passwords.
PKCS#12 Data Management.
PKCS#7 Data Management.
Public and private key management.
Public key algorithm parameter management.
Public key algorithm cryptographic operation utility.
Generate pseudo-random bytes.
PKCS#10 X.509 Certificate Signing Request (CSR) Management.
RSA key management.
RSA utility for signing, verification, encryption, and decryption. Superseded by pkeyutl
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
Time Stamping Authority tool (client/server)
X.509 Certificate Verification.
OpenSSL Version Information.
X.509 Certificate Data Management.


MD2 Digest
MD5 Digest
MDC2 Digest
RMD-160 Digest
SHA Digest
SHA-1 Digest
SHA-224 Digest
SHA-256 Digest
SHA-384 Digest
SHA-512 Digest


Base64 Encoding
Blowfish Cipher
CAST Cipher
CAST5 Cipher
DES Cipher
Triple-DES Cipher
IDEA Cipher
RC2 Cipher
RC4 Cipher
RC5 Cipher


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.
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.


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), passwd(1), pkcs12(1), pkcs7(1), pkcs8(1), rand(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)


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.

2024-02-26 1.0.2u