Provided by: openssl_1.1.1-1ubuntu2.1~18.04.23_amd64 
NAME
openssl-enc, enc - symmetric cipher routines
SYNOPSIS
openssl enc -cipher [-help] [-ciphers] [-in filename] [-out filename] [-pass arg] [-e] [-d] [-a]
[-base64] [-A] [-k password] [-kfile filename] [-K key] [-iv IV] [-S salt] [-salt] [-nosalt] [-z] [-md
digest] [-iter count] [-pbkdf2] [-p] [-P] [-bufsize number] [-nopad] [-debug] [-none] [-rand file...]
[-writerand file] [-engine id]
openssl [cipher] [...]
DESCRIPTION
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.
OPTIONS
-help
Print out a usage message.
-ciphers
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 openssl(1).
-e Encrypt the input data: this is the default.
-d Decrypt the input data.
-a 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.
-base64
Same as -a
-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Superseded by the -pass argument.
-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 Superseded by the -pass argument.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.
-iter count
Use a given number of iterations on the password in deriving the encryption key. High values
increase the time required to brute-force the resulting file. This option enables the use of PBKDF2
algorithm to derive the key.
-pbkdf2
Use PBKDF2 algorithm with default iteration count unless otherwise specified.
-nosalt
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.
-salt
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 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 this password.
-p Print out the key and IV used.
-P 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.
-nopad
Disable standard block padding.
-debug
Debug the BIOs used for I/O.
-z 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.
-none
Use NULL cipher (no encryption or decryption of input).
-rand file...
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.
[-writerand file]
Writes random data to the specified file upon exit. This can be used with a subsequent -rand flag.
NOTES
The program can be called either as openssl cipher or openssl enc -cipher. The first form doesn't work
with engine-provided ciphers, because this form is processed before the configuration file is read and
any ENGINEs loaded. Use the list command to get a list of supported ciphers.
Engines which provide entirely new encryption algorithms (such as the ccgost engine which provides gost89
algorithm) should be configured in the configuration file. Engines specified on the command line using
-engine options can only be used for hardware-assisted implementations of ciphers which are supported by
the OpenSSL core or another engine specified in the configuration file.
When the 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.
The -salt option should ALWAYS be used if the key is being derived from a password unless you want
compatibility with previous versions of OpenSSL.
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, such as AES, in CBC mode.
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 block length.
All RC2 ciphers have the same key and effective key length.
Blowfish and RC5 algorithms use a 128 bit key.
SUPPORTED CIPHERS
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 the
-ciphers option (that is openssl enc -ciphers) produces a list of ciphers, supported by your version of
OpenSSL, including ones provided by configured engines.
The enc program does not support authenticated encryption modes like CCM and GCM, and will not support
such modes in the future. The enc interface by necessity must begin streaming output (e.g., to standard
output when -out is not used before the authentication tag could be validated, leading to the usage of
enc in pipelines that begin processing untrusted data and are not capable of rolling back upon
authentication failure. The AEAD modes currently in common use also suffer from catastrophic failure of
confidentiality and/or integrity upon reuse of key/iv/nonce, and since enc places the entire burden of
key/iv/nonce management upon the user, the risk of exposing AEAD modes is too great to allow. These
key/iv/nonce management issues also affect other modes currently exposed in enc, but the failure modes
are less extreme in these cases, and the functionality cannot be removed with a stable release branch.
For bulk encryption of data, whether using authenticated encryption modes or other modes, cms(1) is
recommended, as it provides a standard data format and performs the needed key/iv/nonce management.
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 CFB 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]-ctr 128/192/256 bit AES in CTR 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
camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
EXAMPLES
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
BUGS
The -A option when used with large files doesn't work properly.
The enc 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.
HISTORY
The default digest was changed from MD5 to SHA256 in Openssl 1.1.0.
COPYRIGHT
Copyright 2000-2018 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
<https://www.openssl.org/source/license.html>.