enc - symmetric cipher routines
openssl enc -ciphername
] [ -ciphers
] [ -in
] [ -out filename
] [ -pass arg
] [ -e
] [ -a/-base64
] [ -A
] [ -k password
] [ -kfile
] [ -K key
] [ -iv IV
] [ -S salt
] [ -nosalt
] [ -z
] [ -md digest
] [ -p
] [ -bufsize number
] [ -nopad
] [ -debug
] [ -engine id
The symmetric cipher commands allow data to be encrypted or decrypted using
various block and stream ciphers using keys based on passwords or explicitly
provided. Base64 encoding or decoding can also be performed either by itself
or in addition to the encryption or decryption.
- Print out a usage message.
- List all supported ciphers.
- -in filename
- the input filename, standard input by default.
- -out filename
- the output filename, standard output by default.
- -pass arg
- the password source. For more information about the format
of arg see the PASS PHRASE ARGUMENTS section in
- encrypt the input data: this is the default.
- decrypt the input data.
- base64 process the data. This means that if encryption is
taking place the data is base64 encoded after encryption. If decryption is
set then the input data is base64 decoded before being decrypted.
- same as -a
- if the -a option is set then base64 process the data
on one line.
- -k password
- the password to derive the key from. This is for
compatibility with previous versions of OpenSSL. Superseded by the
- -kfile filename
- read the password to derive the key from the first line of
filename. This is for compatibility with previous versions of
OpenSSL. Superseded by the -pass argument.
- -md digest
- Use the specified digest to create the key from the
passphrase. The default algorithm is sha-256.
- don't use a salt in the key derivation routines. This
option SHOULD NOT be used except for test purposes or compatibility
with ancient versions of OpenSSL.
- use salt (randomly generated or provide with -S
option) when encrypting (this is the default).
- -S salt
- the actual salt to use: this must be represented as a
string of hex digits.
- -K key
- the actual key to use: this must be represented as a string
comprised only of hex digits. If only the key is specified, the IV must
additionally specified using the -iv option. When both a key and a
password are specified, the key given with the -K option will be
used and the IV generated from the password will be taken. It probably
does not make much sense to specify both key and password.
- -iv IV
- the actual IV to use: this must be represented as a string
comprised only of hex digits. When only the key is specified using the
-K option, the IV must explicitly be defined. When a password is
being specified using one of the other options, the IV is generated from
- print out the key and IV used.
- print out the key and IV used then immediately exit: don't
do any encryption or decryption.
- -bufsize number
- set the buffer size for I/O
- disable standard block padding
- debug the BIOs used for I/O.
- Compress or decompress clear text using zlib before
encryption or after decryption. This option exists only if OpenSSL with
compiled with zlib or zlib-dynamic option.
- Use NULL cipher (no encryption or decryption of
The program can be called either as openssl ciphername
or openssl enc
. But the first form doesn't work with engine-provided ciphers,
because this form is processed before the configuration file is read and any
Engines which provide entirely new encryption algorithms (such as ccgost engine
which provides gost89 algorithm) should be configured in the configuration
file. Engines, specified in the command line using -engine options can only be
used for hardware-assisted implementations of ciphers, which are supported by
OpenSSL core or other engine, specified in the configuration file.
When enc command lists supported ciphers, ciphers provided by engines, specified
in the configuration files are listed too.
A password will be prompted for to derive the key and IV if necessary.
option should ALWAYS
be used if the key is being derived
from a password unless you want compatibility with previous versions of
Without the -salt
option it is possible to perform efficient dictionary
attacks on the password and to attack stream cipher encrypted data. The reason
for this is that without the salt the same password always generates the same
encryption key. When the salt is being used the first eight bytes of the
encrypted data are reserved for the salt: it is generated at random when
encrypting a file and read from the encrypted file when it is decrypted.
Some of the ciphers do not have large keys and others have security implications
if not used correctly. A beginner is advised to just use a strong block cipher
in CBC mode such as bf or des3.
All the block ciphers normally use PKCS#5 padding also known as standard block
padding: this allows a rudimentary integrity or password check to be
performed. However since the chance of random data passing the test is better
than 1 in 256 it isn't a very good test.
If padding is disabled then the input data must be a multiple of the cipher
All RC2 ciphers have the same key and effective key length.
Blowfish and RC5 algorithms use a 128 bit key.
Note that some of these ciphers can be disabled at compile time and some are
available only if an appropriate engine is configured in the configuration
file. The output of the enc
command run with unsupported options (for
example openssl enc -help
) includes a list of ciphers, supported by
your version of OpenSSL, including ones provided by configured engines.
program does not support authenticated encryption modes like CCM
and GCM. The utility does not store or retrieve the authentication tag.
base64 Base 64
bf-cbc Blowfish in CBC mode
bf Alias for bf-cbc
bf-cfb Blowfish in CFB mode
bf-ecb Blowfish in ECB mode
bf-ofb Blowfish in OFB mode
cast-cbc CAST in CBC mode
cast Alias for cast-cbc
cast5-cbc CAST5 in CBC mode
cast5-cfb CAST5 in CFB mode
cast5-ecb CAST5 in ECB mode
cast5-ofb CAST5 in OFB mode
des-cbc DES in CBC mode
des Alias for des-cbc
des-cfb DES in CBC mode
des-ofb DES in OFB mode
des-ecb DES in ECB mode
des-ede-cbc Two key triple DES EDE in CBC mode
des-ede Two key triple DES EDE in ECB mode
des-ede-cfb Two key triple DES EDE in CFB mode
des-ede-ofb Two key triple DES EDE in OFB mode
des-ede3-cbc Three key triple DES EDE in CBC mode
des-ede3 Three key triple DES EDE in ECB mode
des3 Alias for des-ede3-cbc
des-ede3-cfb Three key triple DES EDE CFB mode
des-ede3-ofb Three key triple DES EDE in OFB mode
desx DESX algorithm.
gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
idea-cbc IDEA algorithm in CBC mode
idea same as idea-cbc
idea-cfb IDEA in CFB mode
idea-ecb IDEA in ECB mode
idea-ofb IDEA in OFB mode
rc2-cbc 128 bit RC2 in CBC mode
rc2 Alias for rc2-cbc
rc2-cfb 128 bit RC2 in CFB mode
rc2-ecb 128 bit RC2 in ECB mode
rc2-ofb 128 bit RC2 in OFB mode
rc2-64-cbc 64 bit RC2 in CBC mode
rc2-40-cbc 40 bit RC2 in CBC mode
rc4 128 bit RC4
rc4-64 64 bit RC4
rc4-40 40 bit RC4
rc5-cbc RC5 cipher in CBC mode
rc5 Alias for rc5-cbc
rc5-cfb RC5 cipher in CFB mode
rc5-ecb RC5 cipher in ECB mode
rc5-ofb RC5 cipher in OFB mode
aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
aes[128|192|256] Alias for aes-[128|192|256]-cbc
aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
Just base64 encode a binary file:
openssl base64 -in file.bin -out file.b64
Decode the same file
openssl base64 -d -in file.b64 -out file.bin
Encrypt a file using triple DES in CBC mode using a prompted password:
openssl des3 -salt -in file.txt -out file.des3
Decrypt a file using a supplied password:
openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
Encrypt a file then base64 encode it (so it can be sent via mail for example)
using Blowfish in CBC mode:
openssl bf -a -salt -in file.txt -out file.bf
Base64 decode a file then decrypt it:
openssl bf -d -salt -a -in file.bf -out file.txt
Decrypt some data using a supplied 40 bit RC4 key:
openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
option when used with large files doesn't work properly.
There should be an option to allow an iteration count to be included.
program only supports a fixed number of algorithms with certain
parameters. So if, for example, you want to use RC2 with a 76 bit key or RC4
with an 84 bit key you can't use this program.
The default digest was changed from MD5 to SHA256 in Openssl 1.1.
Copyright 2000-2016 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