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]
       [-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 decryption.


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 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.

       -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

           Superseded by the -pass argument.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 Superseded by the -pass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

       -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 compatibility with
       previous versions of OpenSSL and SSLeay.

       Without the -salt option it is possible to perform

       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 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.

       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           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:


       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.

       Like the EVP library 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.


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