OpenSSL command line tool.
Syntax openssl command [ command_opts ] [ command_args ] openssl [ list-standard-commands | list-message-digest-commands | list-cipher-commands ] openssl no-XXX [ arbitrary options ] STANDARD COMMANDS asn1parse Parse an ASN.1 sequence. ca Certificate Authority (CA) Management. ciphers Cipher Suite Description Determination. crl Certificate Revocation List (CRL) Management. crl2pkcs7 CRL to PKCS#7 Conversion. dgst Message Digest Calculation. dh Diffie-Hellman Parameter Management. Obsoleted by dhparam. dsa DSA Data Management. dsaparam DSA Parameter Generation. enc Encoding with Ciphers. errstr Error Number to Error String Conversion. dhparam Generation and Management of Diffie-Hellman Parameters. gendh Generation of Diffie-Hellman Parameters. Obsoleted by dhparam. gendsa Generation of DSA Parameters. genrsa Generation of RSA Parameters. ocsp Online Certificate Status Protocol utility. passwd Generation of hashed passwords. pkcs12 PKCS#12 Data Management. pkcs7 PKCS#7 Data Management. rand [options] num Generate pseudo-random bytes. When converted to base64, an additional pad character "0" may be suffixed to make the encoded output an integer multiple of 4 characters. If the unencoded binary text is a multiple of 3 bytes (3,6,9,12,15,18...) then no pad characters will be added to the output. 3 bytes> 4 characters, 6 bytes>8 characters etc. req X.509 Certificate Signing Request (CSR) Management. rsa RSA Data Management. rsautl RSA utility for signing, verification, encryption, and decryption. 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. 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.
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
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-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.)
Generate a random 20 character password, 15 random bytes (8 bits each) will be converted to 20 characters in base 64 (6 bits of entropy per character):
openssl rand -base64 15
Verify a manually-downloaded software update (InstallESD.dmg) from Apple Downloads, which contains a SHA-1 digest
$ openssl sha1 /Volumes/Install\ macOS\ Sierra\ 12.5.03/Install\ macOS\ Sierra.app/Contents/SharedSupport/InstallESD.dmg SHA1(/Volumes/Install macOS Sierra 12.5.03/Install macOS Sierra.app/Contents/SharedSupport/InstallESD.dmg)= 51df126965433187403987c9d74d95c26cba9266
This can be compared with a list of known good file hashes. e.g. OSX SHA1 Checksums
"Programming is dreadfully impermanent; it’s more like performance art than literature" ~ Bruce Sterling
Local man page: openssl - Command line help page on your local machine.
asn1parse(1), ca(1), config(5), crl(1), crl2pkcs7(1), dgst(1), dhparam(1), dsa(1), dsaparam(1), enc(1), gendsa(1), genrsa(1), nseq(1)
passwd - Modify a user password.
pbcopy - Copy data to the clipboard.
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)