amcrypt-ossl-asym(8) [debian man page]
AMCRYPT-OSSL-ASYM(8) System Administration Commands AMCRYPT-OSSL-ASYM(8) 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) The Amanda Wiki: : http://wiki.zmanda.com/ AUTHOR
Kevin Till <kevin.till@zmanda.com> Zmanda, Inc. (http://www.zmanda.com) NOTES
1. www.openssl.org http://www.openssl.org/ 2. www.diceware.com http://www.diceware.com/ Amanda 3.3.1 02/21/2012 AMCRYPT-OSSL-ASYM(8)
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AMGPGCRYPT(8) System Administration Commands AMGPGCRYPT(8) NAME
amgpgcrypt - reference crypt program for Amanda public-key data encryption SYNOPSIS
amgpgcrypt to be called by Amanda only DESCRIPTION
amgpgcrypt calls gpg to perform public-key data encryption on Amanda backup. amgpgcrypt will search for the gpg program in the following directories: /usr/local/bin:/usr/bin:/usr/sbin:/bin:/sbin amgpgcrypt sets GNUPGHOME to $AMANDA_HOME/.gnupg where gpg will look for the gpg keys. amgpgcrypt uses the public key to encrypt the Amanda data and uses the private key to decrypt the Amanda backup data. Thus, passphrase is only required at the time of data restore. KEY AND PASSPHRASE
amgpgcrypt uses the private key to decrypt Amanda backup data. It is very important to store, manage and protect the key and the passphrase properly. Encrypted backup data can only be recovered with the correct key and passphrase. HOW TO CREATE ENCRYPTION KEYS AND PASSPHRASE FOR AMGPGCRYPT
Store the passphrase that you used in following "gpg --gen-key" command inside the home-directory of the AMANDA-user($amanda_user) and protect it with proper permissions: echo my_secret_passphrase > ~$amanda_user/.am_passphrase chown $amanda_user:disk ~$amanda_user/.am_passphrase chmod 700 ~$amanda_user/.am_passphrase Run "gpg --gen-key". Below is an example: $ gpg --gen-key gpg (GnuPG) 1.2.6; Copyright (C) 2004 Free Software Foundation, Inc. This program comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to redistribute it under certain conditions. See the file COPYING for details. Please select what kind of key you want: (1) DSA and ElGamal (default) (2) DSA (sign only) (4) RSA (sign only) Your selection? 1 DSA keypair will have 1024 bits. About to generate a new ELG-E keypair. minimum keysize is 768 bits default keysize is 1024 bits highest suggested keysize is 2048 bits What keysize do you want? (1024) Requested keysize is 1024 bits Please specify how long the key should be valid. 0 = key does not expire (n) = key expires in n days (n)w = key expires in n weeks (n)m = key expires in n months (n)y = key expires in n years Key is valid for? (0) 6m Key expires at Sun 06 Aug 2006 03:51:25 PM PDT Is this correct (y/n)? y You need a User-ID to identify your key; the software constructs the user id from Real Name, Comment and Email Address in this form: "Heinrich Heine (Der Dichter) (heinrichh@duesseldorf.de)" Real name: amandabackup Email address: Comment: gpg keys for amandabackup You selected this USER-ID: "amandabackup (gpg keys for amandabackup)" Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o You need a Passphrase to protect your secret key. We need to generate a lot of random bytes. It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize the disks) during the prime generation; this gives the random number generator a better chance to gain enough entropy. We need to generate a lot of random bytes. It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize the disks) during the prime generation; this gives the random number generator a better chance to gain enough entropy. public and secret key created and signed. key marked as ultimately trusted. pub 1024D/4417A8CB 2006-02-07 amandabackup (gpg keys for amandabackup) Key fingerprint = 139C 6369 44FC 7F1A 655C E5E9 7EAA 515A 4417 A8CB sub 1024g/8C3A6A78 2006-02-07 [expires: 2006-08-06] FILES
$AMANDA_HOME/.gnupg/pubring.gpg The public key. amgpgcrypt encrypt data with this public key along with the cipher algorithm. $AMANDA_HOME/.gnupg/secring.gpg The private/secret key. It's only needed during amrecover/amrestore. Store and protect it properly during other time. $AMANDA_HOME/.am_passphrase The passphrase. It's only needed during amrecover/amrestore. Store and protect it properly during other time. BUGS
Amanda has problem with gpg mdc(modification detection code) in the binary mode. amgpgcrypt calls gpg with mdc disabled SEE ALSO
amanda(8), amanda.conf(5), amcrypt(8), amrestore(8), gpg(1) The Amanda Wiki: : http://wiki.zmanda.com/ AUTHOR
Kevin Till <kevin.till@zmanda.com> Zmanda, Inc. (http://www.zmanda.com) Amanda 3.3.1 02/21/2012 AMGPGCRYPT(8)