1 .\" Title: amcrypt-ossl-asym
2 .\" Author: Kevin Till <kevin.till@zmanda.com>
3 .\" Generator: DocBook XSL Stylesheets v1.74.0 <http://docbook.sf.net/>
5 .\" Manual: System Administration Commands
6 .\" Source: Amanda 2.6.1
9 .TH "AMCRYPT\-OSSL\-ASYM" "8" "01/22/2009" "Amanda 2\&.6\&.1" "System Administration Commands"
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170 amcrypt-ossl-asym \- crypt program for \fIAmanda\fR asymmetric data encryption using OpenSSL
173 .HP \w'\fBamcrypt\-ossl\-asym\fR\ 'u
174 \fBamcrypt\-ossl\-asym\fR [\-d]
179 \fBamcrypt\-ossl\-asym\fR
182 to encrypt and decrypt data\&. OpenSSL is available from
183 www\&.openssl\&.org\&. OpenSSL offers a wide variety of cipher choices (
184 \fBamcrypt\-ossl\-asym\fR
185 defaults to 256\-bit AES) and can use hardware cryptographic accelerators on several platforms\&.
188 \fBamcrypt\-ossl\-asym\fR
189 will search for the OpenSSL program in the following directories: /bin:/usr/bin:/usr/local/bin:/usr/ssl/bin:/usr/local/ssl/bin\&.
190 .SH "GENERATING PUBLIC AND PRIVATE KEYS"
192 RSA keys can be generated with the standard OpenSSL commands, e\&.g\&.:
195 $ openssl genrsa \-aes128 \-out backup\-privkey\&.pem 1024
196 Generating RSA private key, 1024 bit long modulus
198 Enter pass phrase for backup\-privkey\&.pem: \fIENTER YOUR PASS PHRASE\fR
199 Verifying \- Enter pass phrase for backup\-key\&.pem: \fIENTER YOUR PASS PHRASE\fR
201 $ openssl rsa \-in backup\-privkey\&.pem \-pubout \-out backup\-pubkey\&.pem
202 Enter pass phrase for backup\-privkey\&.pem: \fIENTER YOUR PASS PHRASE\fR
206 To generate a private key without a passphrase, omit the
209 \fBopenssl_genrsa\fR(1)
210 for more key generation options\&.
212 Note that it is always possible to generate the public key from the private key\&.
213 .SH "KEY AND PASSPHRASE MANAGEMENT"
216 \fBamcrypt\-ossl\-asym\fR
219 to encrypt data\&. The security of the data does not depend on the confidentiality of the public key\&. The
221 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\&.
223 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\&.
225 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
226 www\&.diceware\&.com) can be used to create passphrases that are difficult to guess and easy to remember\&.
229 /var/lib/amanda/backup\-privkey\&.pem
231 File containing the RSA private key\&. It should not be readable by any user other than the
236 /var/lib/amanda/backup\-pubkey\&.pem
238 File containing the RSA public key\&.
241 /var/lib/amanda/\&.am_passphrase
243 File containing the passphrase\&. It should not be readable by any user other than the
251 \fBamanda.conf\fR(5),
253 \fBamcrypt-ossl\fR(8),
254 : http://wiki.zmanda.com
257 \fBKevin Till\fR <\&kevin\&.till@zmanda\&.com\&>
259 Zmanda, Inc\&. (\FChttp://www\&.zmanda\&.com\F[])
265 \%http://www.openssl.org/
270 \%http://www.diceware.com/