432 lines
14 KiB
Plaintext
432 lines
14 KiB
Plaintext
=pod
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=head1 NAME
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openssl-enc,
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enc - symmetric cipher routines
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=head1 SYNOPSIS
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B<openssl enc -I<cipher>>
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[B<-help>]
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[B<-ciphers>]
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[B<-in filename>]
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[B<-out filename>]
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[B<-pass arg>]
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[B<-e>]
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[B<-d>]
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[B<-a>]
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[B<-base64>]
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[B<-A>]
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[B<-k password>]
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[B<-kfile filename>]
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[B<-K key>]
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[B<-iv IV>]
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[B<-S salt>]
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[B<-salt>]
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[B<-nosalt>]
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[B<-z>]
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[B<-md digest>]
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[B<-iter count>]
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[B<-pbkdf2>]
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[B<-p>]
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[B<-P>]
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[B<-bufsize number>]
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[B<-nopad>]
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[B<-debug>]
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[B<-none>]
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[B<-rand file...>]
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[B<-writerand file>]
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[B<-engine id>]
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B<openssl> I<[cipher]> [B<...>]
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=head1 DESCRIPTION
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The symmetric cipher commands allow data to be encrypted or decrypted
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using various block and stream ciphers using keys based on passwords
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or explicitly provided. Base64 encoding or decoding can also be performed
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either by itself or in addition to the encryption or decryption.
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=head1 OPTIONS
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=over 4
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=item B<-help>
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Print out a usage message.
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=item B<-ciphers>
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List all supported ciphers.
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=item B<-in filename>
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The input filename, standard input by default.
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=item B<-out filename>
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The output filename, standard output by default.
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=item B<-pass arg>
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The password source. For more information about the format of B<arg>
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see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
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=item B<-e>
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Encrypt the input data: this is the default.
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=item B<-d>
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Decrypt the input data.
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=item B<-a>
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Base64 process the data. This means that if encryption is taking place
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the data is base64 encoded after encryption. If decryption is set then
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the input data is base64 decoded before being decrypted.
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=item B<-base64>
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Same as B<-a>
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=item B<-A>
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If the B<-a> option is set then base64 process the data on one line.
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=item B<-k password>
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The password to derive the key from. This is for compatibility with previous
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versions of OpenSSL. Superseded by the B<-pass> argument.
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=item B<-kfile filename>
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Read the password to derive the key from the first line of B<filename>.
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This is for compatibility with previous versions of OpenSSL. Superseded by
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the B<-pass> argument.
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=item B<-md digest>
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Use the specified digest to create the key from the passphrase.
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The default algorithm is sha-256.
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=item B<-iter count>
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Use a given number of iterations on the password in deriving the encryption key.
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High values increase the time required to brute-force the resulting file.
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This option enables the use of PBKDF2 algorithm to derive the key.
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=item B<-pbkdf2>
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Use PBKDF2 algorithm with default iteration count unless otherwise specified.
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=item B<-nosalt>
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Don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
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used except for test purposes or compatibility with ancient versions of
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OpenSSL.
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=item B<-salt>
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Use salt (randomly generated or provide with B<-S> option) when
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encrypting, this is the default.
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=item B<-S salt>
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The actual salt to use: this must be represented as a string of hex digits.
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=item B<-K key>
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The actual key to use: this must be represented as a string comprised only
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of hex digits. If only the key is specified, the IV must additionally specified
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using the B<-iv> option. When both a key and a password are specified, the
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key given with the B<-K> option will be used and the IV generated from the
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password will be taken. It does not make much sense to specify both key
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and password.
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=item B<-iv IV>
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The actual IV to use: this must be represented as a string comprised only
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of hex digits. When only the key is specified using the B<-K> option, the
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IV must explicitly be defined. When a password is being specified using
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one of the other options, the IV is generated from this password.
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=item B<-p>
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Print out the key and IV used.
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=item B<-P>
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Print out the key and IV used then immediately exit: don't do any encryption
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or decryption.
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=item B<-bufsize number>
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Set the buffer size for I/O.
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=item B<-nopad>
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Disable standard block padding.
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=item B<-debug>
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Debug the BIOs used for I/O.
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=item B<-z>
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Compress or decompress clear text using zlib before encryption or after
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decryption. This option exists only if OpenSSL with compiled with zlib
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or zlib-dynamic option.
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=item B<-none>
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Use NULL cipher (no encryption or decryption of input).
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=item B<-rand file...>
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A file or files containing random data used to seed the random number
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generator.
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Multiple files can be specified separated by an OS-dependent character.
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The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
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all others.
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=item [B<-writerand file>]
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Writes random data to the specified I<file> upon exit.
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This can be used with a subsequent B<-rand> flag.
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=back
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=head1 NOTES
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The program can be called either as B<openssl cipher> or
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B<openssl enc -cipher>. The first form doesn't work with
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engine-provided ciphers, because this form is processed before the
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configuration file is read and any ENGINEs loaded.
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Use the B<list> command to get a list of supported ciphers.
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Engines which provide entirely new encryption algorithms (such as the ccgost
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engine which provides gost89 algorithm) should be configured in the
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configuration file. Engines specified on the command line using -engine
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options can only be used for hardware-assisted implementations of
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ciphers which are supported by the OpenSSL core or another engine specified
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in the configuration file.
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When the enc command lists supported ciphers, ciphers provided by engines,
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specified in the configuration files are listed too.
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A password will be prompted for to derive the key and IV if necessary.
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The B<-salt> option should B<ALWAYS> be used if the key is being derived
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from a password unless you want compatibility with previous versions of
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OpenSSL.
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Without the B<-salt> option it is possible to perform efficient dictionary
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attacks on the password and to attack stream cipher encrypted data. The reason
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for this is that without the salt the same password always generates the same
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encryption key. When the salt is being used the first eight bytes of the
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encrypted data are reserved for the salt: it is generated at random when
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encrypting a file and read from the encrypted file when it is decrypted.
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Some of the ciphers do not have large keys and others have security
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implications if not used correctly. A beginner is advised to just use
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a strong block cipher, such as AES, in CBC mode.
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All the block ciphers normally use PKCS#5 padding, also known as standard
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block padding. This allows a rudimentary integrity or password check to
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be performed. However since the chance of random data passing the test
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is better than 1 in 256 it isn't a very good test.
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If padding is disabled then the input data must be a multiple of the cipher
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block length.
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All RC2 ciphers have the same key and effective key length.
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Blowfish and RC5 algorithms use a 128 bit key.
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=head1 SUPPORTED CIPHERS
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Note that some of these ciphers can be disabled at compile time
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and some are available only if an appropriate engine is configured
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in the configuration file. The output of the B<enc> command run with
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the B<-ciphers> option (that is B<openssl enc -ciphers>) produces a
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list of ciphers, supported by your version of OpenSSL, including
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ones provided by configured engines.
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The B<enc> program does not support authenticated encryption modes
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like CCM and GCM, and will not support such modes in the future.
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The B<enc> interface by necessity must begin streaming output (e.g.,
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to standard output when B<-out> is not used) before the authentication
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tag could be validated, leading to the usage of B<enc> in pipelines
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that begin processing untrusted data and are not capable of rolling
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back upon authentication failure. The AEAD modes currently in common
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use also suffer from catastrophic failure of confidentiality and/or
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integrity upon reuse of key/iv/nonce, and since B<enc> places the
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entire burden of key/iv/nonce management upon the user, the risk of
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exposing AEAD modes is too great to allow. These key/iv/nonce
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management issues also affect other modes currently exposed in B<enc>,
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but the failure modes are less extreme in these cases, and the
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functionality cannot be removed with a stable release branch.
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For bulk encryption of data, whether using authenticated encryption
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modes or other modes, L<cms(1)> is recommended, as it provides a
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standard data format and performs the needed key/iv/nonce management.
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base64 Base 64
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bf-cbc Blowfish in CBC mode
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bf Alias for bf-cbc
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blowfish Alias for bf-cbc
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bf-cfb Blowfish in CFB mode
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bf-ecb Blowfish in ECB mode
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bf-ofb Blowfish in OFB mode
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cast-cbc CAST in CBC mode
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cast Alias for cast-cbc
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cast5-cbc CAST5 in CBC mode
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cast5-cfb CAST5 in CFB mode
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cast5-ecb CAST5 in ECB mode
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cast5-ofb CAST5 in OFB mode
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chacha20 ChaCha20 algorithm
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des-cbc DES in CBC mode
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des Alias for des-cbc
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des-cfb DES in CFB mode
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des-ofb DES in OFB mode
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des-ecb DES in ECB mode
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des-ede-cbc Two key triple DES EDE in CBC mode
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des-ede Two key triple DES EDE in ECB mode
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des-ede-cfb Two key triple DES EDE in CFB mode
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des-ede-ofb Two key triple DES EDE in OFB mode
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des-ede3-cbc Three key triple DES EDE in CBC mode
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des-ede3 Three key triple DES EDE in ECB mode
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des3 Alias for des-ede3-cbc
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des-ede3-cfb Three key triple DES EDE CFB mode
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des-ede3-ofb Three key triple DES EDE in OFB mode
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desx DESX algorithm.
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gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
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gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
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idea-cbc IDEA algorithm in CBC mode
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idea same as idea-cbc
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idea-cfb IDEA in CFB mode
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idea-ecb IDEA in ECB mode
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idea-ofb IDEA in OFB mode
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rc2-cbc 128 bit RC2 in CBC mode
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rc2 Alias for rc2-cbc
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rc2-cfb 128 bit RC2 in CFB mode
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rc2-ecb 128 bit RC2 in ECB mode
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rc2-ofb 128 bit RC2 in OFB mode
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rc2-64-cbc 64 bit RC2 in CBC mode
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rc2-40-cbc 40 bit RC2 in CBC mode
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rc4 128 bit RC4
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rc4-64 64 bit RC4
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rc4-40 40 bit RC4
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rc5-cbc RC5 cipher in CBC mode
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rc5 Alias for rc5-cbc
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rc5-cfb RC5 cipher in CFB mode
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rc5-ecb RC5 cipher in ECB mode
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rc5-ofb RC5 cipher in OFB mode
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seed-cbc SEED cipher in CBC mode
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seed Alias for seed-cbc
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seed-cfb SEED cipher in CFB mode
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seed-ecb SEED cipher in ECB mode
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seed-ofb SEED cipher in OFB mode
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sm4-cbc SM4 cipher in CBC mode
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sm4 Alias for sm4-cbc
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sm4-cfb SM4 cipher in CFB mode
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sm4-ctr SM4 cipher in CTR mode
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sm4-ecb SM4 cipher in ECB mode
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sm4-ofb SM4 cipher in OFB mode
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aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
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aes[128|192|256] Alias for aes-[128|192|256]-cbc
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aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
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aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
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aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
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aes-[128|192|256]-ctr 128/192/256 bit AES in CTR mode
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aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
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aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
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aria-[128|192|256]-cbc 128/192/256 bit ARIA in CBC mode
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aria[128|192|256] Alias for aria-[128|192|256]-cbc
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aria-[128|192|256]-cfb 128/192/256 bit ARIA in 128 bit CFB mode
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aria-[128|192|256]-cfb1 128/192/256 bit ARIA in 1 bit CFB mode
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aria-[128|192|256]-cfb8 128/192/256 bit ARIA in 8 bit CFB mode
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aria-[128|192|256]-ctr 128/192/256 bit ARIA in CTR mode
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aria-[128|192|256]-ecb 128/192/256 bit ARIA in ECB mode
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aria-[128|192|256]-ofb 128/192/256 bit ARIA in OFB mode
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camellia-[128|192|256]-cbc 128/192/256 bit Camellia in CBC mode
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camellia[128|192|256] Alias for camellia-[128|192|256]-cbc
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camellia-[128|192|256]-cfb 128/192/256 bit Camellia in 128 bit CFB mode
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camellia-[128|192|256]-cfb1 128/192/256 bit Camellia in 1 bit CFB mode
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camellia-[128|192|256]-cfb8 128/192/256 bit Camellia in 8 bit CFB mode
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camellia-[128|192|256]-ctr 128/192/256 bit Camellia in CTR mode
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camellia-[128|192|256]-ecb 128/192/256 bit Camellia in ECB mode
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camellia-[128|192|256]-ofb 128/192/256 bit Camellia in OFB mode
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=head1 EXAMPLES
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Just base64 encode a binary file:
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openssl base64 -in file.bin -out file.b64
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Decode the same file
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openssl base64 -d -in file.b64 -out file.bin
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Encrypt a file using AES-128 using a prompted password
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and PBKDF2 key derivation:
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openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128
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Decrypt a file using a supplied password:
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openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \
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-pass pass:<password>
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Encrypt a file then base64 encode it (so it can be sent via mail for example)
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using AES-256 in CTR mode and PBKDF2 key derivation:
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openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256
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Base64 decode a file then decrypt it using a password supplied in a file:
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openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \
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-pass file:<passfile>
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=head1 BUGS
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The B<-A> option when used with large files doesn't work properly.
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The B<enc> program only supports a fixed number of algorithms with
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certain parameters. So if, for example, you want to use RC2 with a
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76 bit key or RC4 with an 84 bit key you can't use this program.
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=head1 HISTORY
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The default digest was changed from MD5 to SHA256 in OpenSSL 1.1.0.
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=head1 COPYRIGHT
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Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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