1AMCRYPT-OSSL-ASYM(8) System Administration Commands AMCRYPT-OSSL-ASYM(8)
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6 amcrypt-ossl-asym - crypt program for Amanda asymmetric data encryption
7 using OpenSSL
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10 amcrypt-ossl-asym [-d]
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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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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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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 OpenSSLĀ“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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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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74 amanda(8), amanda.conf(5), openssl(1), amcrypt-ossl(8)
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76 The Amanda Wiki: : http://wiki.zmanda.com/
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79 Kevin Till <kevin.till@zmanda.com>
80 Zmanda, Inc. (http://www.zmanda.com)
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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 3.1.3 10/04/2010 AMCRYPT-OSSL-ASYM(8)