Manual Pages for UNIX Darwin command on man enc

ENC(1) OpenSSL ENC(1)

NAME

enc - symmetric cipher routines

SYNOPSIS

ooppeennssssll eenncc -cciipphheerrnnaammee [-iinn ffiilleennaammee] [-oouutt ffiilleennaammee] [-ppaassss aarrgg] [-ee]

[-dd] [-aa] [-AA] [-kk ppaasssswwoorrdd] [-kkffiillee ffiilleennaammee] [-KK kkeeyy] [-iivv IIVV] [-pp]

[-PP] [-bbuuffssiizzee nnuummbbeerr] [-nnooppaadd] [-ddeebbuugg]

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.

OOPPTTIIOONNSS

-iinn ffiilleennaammee

the input filename, standard input by default.

-oouutt ffiilleennaammee

the output filename, standard output by default.

-ppaassss aarrgg

the password source. For more information about the format of aarrgg see the PPAASSSS PPHHRRAASSEE AARRGGUUMMEENNTTSS section in openssl(1).

-ssaalltt

use a salt in the key derivation routines. This option should AALLWWAAYYSS 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.

-nnoossaalltt

don't use a salt in the key derivation routines. This is the default for compatibility with previous versions of OpenSSL and SSLeay.

-ee encrypt the input data: this is the default.

-dd decrypt the input data.

-aa 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.

-AA if the -aa option is set then base64 process the data on one line.

-kk ppaasssswwoorrdd

the password to derive the key from. This is for compatibility with

previous versions of OpenSSL. Superseded by the -ppaassss argument.

-kkffiillee ffiilleennaammee

read the password to derive the key from the first line of ffiilleennaammee. This is for compatibility with previous versions of

OpenSSL. Superseded by the -ppaassss argument.

-SS ssaalltt

the actual salt to use: this must be represented as a string comprised only of hex digits.

-KK kkeeyy

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 -iivv option. When both a key

and a password are specified, the key given with the -KK 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.

-iivv IIVV

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 -KK 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.

-pp print out the key and IV used.

-PP print out the key and IV used then immediately exit: don't do any

encryption or decryption.

-bbuuffssiizzee nnuummbbeerr

set the buffer size for I/O

-nnooppaadd

disable standard block padding

-ddeebbuugg

debug the BIOs used for I/O. NNOOTTEESS The program can be called either as ooppeennssssll cciipphheerrnnaammee or ooppeennssssll eenncc

-cciipphheerrnnaammee.

A password will be prompted for to derive the key and IV if necessary.

The -ssaalltt option should AALLWWAAYYSS be used if the key is being derived from

a password unless you want compatibility with previous versions of OpenSSL and SSLeay.

Without the -ssaalltt 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. SSUUPPPPOORRTTEEDD CCIIPPHHEERRSS 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.

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

EEXXAAMMPPLLEESS

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

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

0.9.7l 2005-09-15 ENC(1)