ENC(1)                      OpenSSL                      ENC(1)





NAME
       enc - symmetric cipher routines

SYNOPSIS
       openssl enc -ciphername [-in filename] [-out filename]
       [-pass arg] [-e] [-d] [-a] [-A] [-k password] [-kfile
       filename] [-K key] [-iv IV] [-p] [-P] [-bufsize number]
       [-nopad] [-debug]

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 decryp-
       tion.

OPTIONS
       -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).

       -salt
           use a salt in the key derivation routines. This
           option should ALWAYS be used unless compatibility
           with previous versions of OpenSSL or SSLeay is
           required. This option is only present on OpenSSL
           versions 0.9.5 or above.

       -nosalt
           don't use a salt in the key derivation routines.
           This is the default for compatibility with previous
           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 encryp-
           tion is taking place the data is base64 encoded
           after encryption. If decryption is set then the
           input data is base64 decoded before being decrypted.

       -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           Superseded by the -pass argument.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 computability with
           previous versions of OpenSSL. Superseded by the
           -pass argument.

       -S salt
           the actual salt to use: this must be represented as
           a string comprised only 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 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.

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

       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 compati-
       bility with previous versions of OpenSSL and SSLeay.

       Without the -salt option it is possible to perform effi-
       cient 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 rudimen-
       tary integrity or password check to be performed. How-
       ever 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
        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            Alias for des-ede
        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           Alias for des-ede3-cbc
        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.

        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 CBC mode
        rc2-ecb            128 bit RC2 in CBC mode
        rc2-ofb            128 bit RC2 in CBC 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 CBC mode
        rc5-ecb            RC5 cipher in CBC mode
        rc5-ofb            RC5 cipher in CBC 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.

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

       The enc program only supports a fixed number of algo-
       rithms 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.



0.9.7c                     2001-09-07                    ENC(1)
