amcrypt-ossl-asym(8)

1AMCRYPT-OSSL-ASYM(8)    System Administration Commands    AMCRYPT-OSSL-ASYM(8)
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NAME

6       amcrypt-ossl-asym - crypt program for Amanda asymmetric data encryption
7       using OpenSSL
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SYNOPSIS

10       amcrypt-ossl-asym [-d]
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DESCRIPTION

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

23       RSA keys can be generated with the standard OpenSSL commands, e.g.:
24       $ cd /var/lib/amanda
25       $ openssl genrsa -aes128 -out backup-privkey.pem 1024
26       Generating RSA private key, 1024 bit long modulus
27       [...]
28       Enter pass phrase for backup-privkey.pem: ENTER YOUR PASS PHRASE
29       Verifying - Enter pass phrase for backup-key.pem: ENTER YOUR PASS PHRASE
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31       $ openssl rsa -in backup-privkey.pem -pubout -out backup-pubkey.pem
32       Enter pass phrase for backup-privkey.pem: ENTER YOUR PASS PHRASE
33       Writing RSA key
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35       To generate a private key without a passphrase, omit the -aes128
36       option. See openssl_genrsa(1) for more key generation options.
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38       Note that it is always possible to generate the public key from the
39       private key.
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KEY AND PASSPHRASE MANAGEMENT

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

62       /var/lib/amanda/backup-privkey.pem
63           File containing the RSA private key. It should not be readable by
64           any user other than the Amanda user.
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66       /var/lib/amanda/backup-pubkey.pem
67           File containing the RSA public key.
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69       /var/lib/amanda/.am_passphrase
70           File containing the passphrase. It should not be readable by any
71           user other than the Amanda user.
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AUTHOR

79       Kevin Till <kevin.till@zmanda.com>
80           Zmanda, Inc. (http://www.zmanda.com)
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NOTES

83        1. www.openssl.org
84           http://www.openssl.org/
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86        2. www.diceware.com
87           http://www.diceware.com/
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91Amanda 3.5.1                      12/01/2017              AMCRYPT-OSSL-ASYM(8)