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Updated: Wednesday, February 9, 2022

enc (1openssl)


enc - symmetric cipher routines


openssl enc -ciphername [-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] [-p] [-P] [-bufsize number]
[-nopad] [-debug] [-none] [-engine id]


ENC(1openssl)                       OpenSSL                      ENC(1openssl)

       openssl-enc, enc - symmetric cipher routines

       openssl enc -ciphername [-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] [-p] [-P] [-bufsize number]
       [-nopad] [-debug] [-none] [-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.

       -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).

           use a salt in the key derivation routines. This is the default.

           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 and SSLeay.

       -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.

           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 Superseded by the -pass argument.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.

           do not use a 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

       -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 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

           disable standard block padding

           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.

           Use NULL cipher (no encryption or decryption of input).

       See attributes(7) for descriptions of the following attributes:

       |Availability   | library/security/openssl |
       |Stability      | Pass-through uncommitted |

       The program can be called either as openssl ciphername or openssl enc
       -ciphername. 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 loaded.

       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 hadrware-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.

       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 and SSLeay.

       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 block length.

       All RC2 ciphers have the same key and effective key length.

       Blowfish and RC5 algorithms use a 128 bit key.

       Source code for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-

       This software was built from source available at
       https://github.com/oracle/solaris-userland.  The original community
       source was downloaded from

       Further information about this software can be found on the open source
       community website at https://www.openssl.org/.

       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 versesion of OpenSSL, including ones provided by
       configured engines.

       The enc program does not support authenticated encryption modes like
       CCM and GCM. The utility does not store or retrieve the authentication

        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

       The -A option when used with large files doesn't work properly.

       There should be an option to allow an iteration count to be included.

       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.

1.0.2za                           2021-08-24                     ENC(1openssl)