
                       amcrypt-ossl-asym
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Name

amcrypt-ossl-asym  crypt program for Amanda asymmetric data encryption using
OpenSSL

Synopsis

amcrypt-ossl-asym [-d]

DESCRIPTION

amcrypt-ossl-asym uses OpenSSL to encrypt and decrypt data. OpenSSL is
available from www.openssl.org. OpenSSL offers a wide variety of cipher choices
( amcrypt-ossl-asym defaults to 256-bit AES) and can use hardware cryptographic
accelerators on several platforms.
amcrypt-ossl-asym will search for the OpenSSL program in the following
directories: /bin:/usr/bin:/usr/local/bin:/usr/ssl/bin:/usr/local/ssl/bin.

GENERATING PUBLIC AND PRIVATE KEYS

RSA keys can be generated with the standard OpenSSL commands, e.g.:

  $ cd /var/lib/amanda
  $ openssl genrsa -aes128 -out backup-privkey.pem 1024
  Generating RSA private key, 1024 bit long modulus
  [...]
  Enter pass phrase for backup-privkey.pem: ENTER YOUR PASS PHRASE
  Verifying - Enter pass phrase for backup-key.pem: ENTER YOUR PASS PHRASE

  $ openssl rsa -in backup-privkey.pem -pubout -out backup-pubkey.pem
  Enter pass phrase for backup-privkey.pem: ENTER YOUR PASS PHRASE
  Writing RSA key

To generate a private key without a passphrase, omit the -aes128 option. See
openssl_genrsa(1) for more key generation options.
Note that it is always possible to generate the public key from the private
key.

KEY AND PASSPHRASE MANAGEMENT

amcrypt-ossl-asym uses the public key to encrypt data. The security of the data
does not depend on the confidentiality of the public key. The private key is
used to decrypt data, and must be protected. Encrypted backup data cannot be
recovered without the private key. The private key may optionally be encrypted
with a passphrase.
While the public key must be online at all times to perorm backups, the private
key and optional passphrase are only needed to restore data. It is recommended
that the latter be stored offline all other times. For example, you could keep
the private key on removable media, and copy it into place for a restore; or
you could keep the private key online, encrypted with a passphrase that is
present only for a restore.
OpenSSL's key derivation routines use a salt to guard against dictionary
attacks on the pass phrase; still it is important to pick a pass phrase that is
hard to guess. The Diceware method (see www.diceware.com) can be used to create
passphrases that are difficult to guess and easy to remember.

FILES



  /var/lib/amanda/backup-privkey.pem
      File containing the RSA private key. It should not be readable by any
      user other than the Amanda user.

  /var/lib/amanda/backup-pubkey.pem
      File containing the RSA public key.

  /var/lib/amanda/.am_passphrase
      File containing the passphrase. It should not be readable by any user
      other than the Amanda user.


SEE ALSO

amanda(8), amanda.conf(5), openssl(1), amcrypt-ossl(8)
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