AESPIPE(1)							     COMMANDS								AESPIPE(1)

NAME

       aespipe - AES encrypting or decrypting pipe

SYNOPSIS

       aespipe [options] <inputfile >outputfile

DESCRIPTION

       aespipe	reads  from  standard input and writes to standard output. It can be used to create and restore encrypted tar or cpio archives. It
       can be used to encrypt and decrypt loop-AES compatible encrypted disk images.  aespipe encrypts and decrypts blocks of  data.  If  you  are
       looking for general purpose encrypting tool that preserves data size at byte granularity, then please take a look at GnuPG.

       The AES cipher is used in CBC (cipher block chaining) mode. Data is encrypted and decrypted in 512 byte chains.	aespipe supports three key
       setup modes; single-key, multi-key-v2 and multi-key-v3 modes. Single-key mode uses simple sector IV and one AES key to encrypt and  decrypt
       all  data  sectors.  Multi-key-v2 mode uses cryptographically more secure MD5 IV and 64 different AES keys to encrypt and decrypt data sec-
       tors.  In multi-key mode first key is used for first sector, second key for second sector, and so on. Multi-key-v3 is same as  multi-key-v2
       except  is uses one extra 65th key as additional input to MD5 IV computation. See -K option for more information about how to enable multi-
       key-v3 mode.

       Recommended key setup mode is multi-key-v3, which is based on gpg encrypted key files. In this mode, the passphrase  is	protected  against
       optimized dictionary attacks via salting and key iteration of gpg. Passphrase length should be 20 characters or more.

       Single-key  mode preserves input size at 16 byte granularity. Multi-key mode preserves input size at 512 byte granularity. If input size is
       not multiple of 16 or 512 bytes, input data is padded with null bytes so that both input and output sizes are multiples of 16 or 512 bytes.

       If "ulimit -l" is set to "unlimited" then aespipe attempts to lock its RAM so that encryption keys do not  leak	to  unencrypted  swap.	If
       "ulimit -l" is something other than "unlimited" then aespipe will proceed without locked RAM.

OPTIONS

       -A gpgAgentSocket
	      Read  passphrase	of  gpg encrypted key file from gpg-agent instead of the terminal. aespipe runs gpg to decrypt a key file, and gpg
	      talks to gpg-agent using gpgAgentSocket. Usually this data is in GPG_AGENT_INFO environment variable. The environment that is passed
	      to  gpg  is very minimal.  Normally gpg passes some environment variables to gpg-agent, but in this case, there aren't any. For best
	      results, you may want to configure gpg-agent so that it "keeps" and uses its own environment.  Defining  "keep-tty",  "keep-display"
	      and "pinentry-program" in $HOME/.gnupg/gpg-agent.conf configuration file is a good start.

       -C itercountk
	      Runs  hashed passphrase through itercountk thousand iterations of AES-256 before using it for data encryption. This consumes lots of
	      CPU cycles at program start time but not thereafter. In combination with passphrase seed this slows down dictionary attacks.  Itera-
	      tion is not done in multi-key mode.

       -d     Decrypt data. If this option is not specified, default operation is to encrypt data.

       -e encryption
	      Following  encryption  types are recognized: AES128 (default), AES192 and AES256. Encryption type names are case insensitive. AES128
	      defaults to using SHA-256 passphrase hash, AES192 defaults to using SHA-384 passphrase hash, and AES256 defaults	to  using  SHA-512
	      passphrase hash.

       -G gpghome
	      Set  gpg	home  directory  to gpghome, so that gpg uses public/private keys on gpghome directory. This is only used when gpgkey file
	      needs to be decrypted using public/private keys. If gpgkey file is encrypted with symmetric cipher only, public/private keys are not
	      required and this option has no effect.

       -H phash
	      Uses  phash  function  to  hash  passphrase. Available hash functions are sha256, sha384, sha512 and rmd160. unhashed1 and unhashed2
	      functions also exist for compatibility with some obsolete implementations. Hash type names are case insensitive.

       -K gpgkey
	      Passphrase is piped to gpg so that gpg can decrypt file gpgkey which contains the real keys  that  are  used  to	encrypt  data.	If
	      decryption  requires  public/private  keys  and gpghome is not specified, all users use their own gpg public/private keys to decrypt
	      gpgkey. Decrypted gpgkey should contain 1 or 64 or 65 keys, each key at least 20 characters and separated by newline.  If  decrypted
	      gpgkey  contains	64  or 65 keys, then aespipe is put to multi-key mode. 65th key, if present, is used as additional input to MD5 IV
	      computation.

       -O sectornumber
	      Set IV offset in 512 byte units. Default is zero. Data is encrypted in 512 byte CBC chains and each 512 byte chain  starts  with	IV
	      whose  computation  depends  on  offset within the data. This option can be used to start encryption or decryption in middle of some
	      existing encrypted disk image.

       -p fdnumber
	      Read the passphrase from file descriptor fdnumber instead of the terminal. If -K option is not being used (no gpg  key  file),  then
	      aespipe  attempts  to  read 65 keys from passwdfd, each key at least 20 characters and separated by newline. If aespipe successfully
	      reads 64 or 65 keys, then aespipe is put to multi-key mode. If aespipe encounters end-of-file before 64 keys  are  read,	then  only
	      first key is used in single-key mode.

       -P cleartextkey
	      Read  the  passphrase from file cleartextkey instead of the terminal. If -K option is not being used (no gpg key file), then aespipe
	      attempts to read 65 keys from cleartextkey, each key at least 20 characters and separated by newline. If aespipe successfully  reads
	      64 or 65 keys, then aespipe is put to multi-key mode. If aespipe encounters end-of-file before 64 keys are read, then only first key
	      is used in single-key mode. If both -p and -P options are used, then -p option takes precedence. These are equivalent:

	      aespipe -p3 -K foo.gpg -e AES128 ...   3<someFileName

	      aespipe -P someFileName -K foo.gpg -e AES128 ...

	      In first line of above example, in addition to normal open file descriptors (0==stdin 1==stdout 2==stderr), shell opens the file and
	      passes open file descriptor to started aespipe program. In second line of above example, aespipe opens the file itself.

       -q     Be quiet and don't complain about write errors.

       -S pseed
	      Sets encryption passphrase seed pseed which is appended to user supplied passphrase before hashing. Using different seeds makes dic-
	      tionary attacks slower but does not prevent them if user supplied passphrase is guessable.  Seed is not used in multi-key mode.

       -T     Asks passphrase twice instead of just once.

       -v     Verbose mode. Prints diagnostics to stderr about key length, single/multi key mode, and selected code optimizations  (x86/amd64/pad-
	      lock/intelaes).

       -w number
	      Wait number seconds before asking passphrase.

RETURN VALUE

       aespipe returns 0 on success, nonzero on failure.

AVAILABILITY

       Source is available from http://loop-aes.sourceforge.net/

AUTHORS

       Jari Ruusu

LINUX
								 February 23 2011							AESPIPE(1)