2 .\" Title: amcrypt-ossl-asym
3 .\" Author: Kevin Till <kevin.till@zmanda.com>
4 .\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
6 .\" Manual: System Administration Commands
7 .\" Source: Amanda 3.3.2
10 .TH "AMCRYPT\-OSSL\-ASYM" "8" "07/25/2012" "Amanda 3\&.3\&.2" "System Administration Commands"
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12 .\" * Define some portability stuff
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15 .\" http://bugs.debian.org/507673
16 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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21 .\" * set default formatting
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28 .\" * MAIN CONTENT STARTS HERE *
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31 amcrypt-ossl-asym \- crypt program for Amanda asymmetric data encryption using OpenSSL
33 .HP \w'\fBamcrypt\-ossl\-asym\fR\ 'u
34 \fBamcrypt\-ossl\-asym\fR [\-d]
38 \fBamcrypt\-ossl\-asym\fR
41 to encrypt and decrypt data\&. OpenSSL is available from
42 www\&.openssl\&.org\&. OpenSSL offers a wide variety of cipher choices (
43 \fBamcrypt\-ossl\-asym\fR
44 defaults to 256\-bit AES) and can use hardware cryptographic accelerators on several platforms\&.
47 \fBamcrypt\-ossl\-asym\fR
48 will search for the OpenSSL program in the following directories: /bin:/usr/bin:/usr/local/bin:/usr/ssl/bin:/usr/local/ssl/bin\&.
49 .SH "GENERATING PUBLIC AND PRIVATE KEYS"
51 RSA keys can be generated with the standard OpenSSL commands, e\&.g\&.:
54 $ openssl genrsa \-aes128 \-out backup\-privkey\&.pem 1024
55 Generating RSA private key, 1024 bit long modulus
57 Enter pass phrase for backup\-privkey\&.pem: \fIENTER YOUR PASS PHRASE\fR
58 Verifying \- Enter pass phrase for backup\-key\&.pem: \fIENTER YOUR PASS PHRASE\fR
60 $ openssl rsa \-in backup\-privkey\&.pem \-pubout \-out backup\-pubkey\&.pem
61 Enter pass phrase for backup\-privkey\&.pem: \fIENTER YOUR PASS PHRASE\fR
65 To generate a private key without a passphrase, omit the
68 \fBopenssl_genrsa\fR(1)
69 for more key generation options\&.
71 Note that it is always possible to generate the public key from the private key\&.
72 .SH "KEY AND PASSPHRASE MANAGEMENT"
75 \fBamcrypt\-ossl\-asym\fR
78 to encrypt data\&. The security of the data does not depend on the confidentiality of the public key\&. The
80 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\&.
82 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\&.
84 OpenSSL\*(Aqs 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
85 www\&.diceware\&.com) can be used to create passphrases that are difficult to guess and easy to remember\&.
88 /var/lib/amanda/backup\-privkey\&.pem
90 File containing the RSA private key\&. It should not be readable by any user other than the Amanda user\&.
93 /var/lib/amanda/backup\-pubkey\&.pem
95 File containing the RSA public key\&.
98 /var/lib/amanda/\&.am_passphrase
100 File containing the passphrase\&. It should not be readable by any user other than the Amanda user\&.
105 \fBamanda.conf\fR(5),
107 \fBamcrypt-ossl\fR(8)
110 : http://wiki.zmanda.com/
113 \fBKevin Till\fR <\&kevin\&.till@zmanda\&.com\&>
115 Zmanda, Inc\&. (http://www\&.zmanda\&.com)
121 \%http://www.openssl.org/
126 \%http://www.diceware.com/