Satish BysanyArchiveAbout

Password management using GNU recutils

GNU recutils is a an under-appreciated piece of software. When MySQL or even SQlite is an overkill, recutils fits the bill. It is a database which is

Recutils also comes with many command-line programs to manipulate the text files, such as recins, recdel, etc. Since there aren’t that many online resources available, I thought of writing a small tutorial using a password manager as an example.

Installation

Recutils is available for both DEB and RPM-based systems. Choose your poison:

sudo apt-get install recutils
sudo yum install recutils

But of course, you can always build it from upstream sources. It takes just a couple of minutes:

# dependencies
sudo apt-get install libgcrypt-dev libreadline-dev

# Download the package and verify its authenticity
wget https://ftp.gnu.org/gnu/recutils/recutils-1.7.tar.gz
wget https://ftp.gnu.org/gnu/recutils/recutils-1.7.tar.gz.sig

# The tarball is signed by recutils' developer Jose E. Marchesi
gpg --keyserver keys.gnupg.net --recv-keys B304AF08
gpg --verify recutils-1.7.tar.gz.sig recutils-1.7.tar.gz

# Unpack and install
tar xf recutils-1.7.tar.gz
cd recutils-1.7/

./configure  --prefix=/usr/local --enable-static --disable-shared \
     --enable-encryption --with-pic --disable-dependency-tracking

make -j4
sudo make install

A Music Database

In the simplest case, a recfile is a collection of records. A record is a collection of fields. Create a text file music.rec to hold music records:

# Comments begin with a #. Fields starting with a percentage are special.
%rec: MusicDB

# Multiline fields are separated by a + sign in column 1 followed by a space
Title: Siva Sankari
Movie: Jagadeka Veeruni Katha
Singer: Ghantasala
Actor: NTR
Year: 1961
Comment: This song is renowned for being very
+ hard to sing.

Yes. That’s all it takes to create a database ! The above file contains one record with six fields. New entries can be inserted into the database by the recins program as well:

recins -t MusicDB -r "Title: Suprabhatam" -r "Album: Venkatesha Suprabhatam" \
       -f "Artist" -v "M.S. Subbulakshmi" music.rec

tail -4 music.rec

Title: Suprabhatam
Album: Venkatesha Suprabhatam
Artist: M.S. Subbulakshmi

Fields and values can be specified separately (with -f and -v) or together (with -r). The type/title of the record is given with -t (must match the %rec line in the file).

The PasswordDB

Here’s a more detailed database. Create a file called mysecrects.rec with these contents:

%rec: PasswordDB
%key: Title
%sort: Title
%confidential: Password
%typedef: Date_t date
%type: Date Date_t
%auto: Date

The title of the record is given by %rec. In our example, the PasswordDB record consists of six fields: Title, Username, Password, URL, Date and Comment. The records are sorted by the field indicated by %sort. The records themselves are indexed by %key. In the above example, both are Title. The Password field is marked as %confidential and it will be encrypted automatically during entry insertion. The last three lines enable us to insert the Date field automatically. Note that %key is a synonym for %unique and %mandatory (meaning Title must be unique for the given record and every entry compulsorily contains a title).

A record can be empty. Let’s insert our first entry using recins as before:

# Bash doesn't store in history any command that begins with a leading space
# whenever HISTCONTROL=ignoreboth (which is the default)
 recins -t PasswordDB -r "Title: Gmail" -r "Username: myuser" \
        -r "URL: http://gmail.com"   \
        -f Comment -v 'This is
an example of multiline comment.
It holds my Gmail secrets'           \
        -r "Password: gmailpasswd" -s mysecrets.rec 

Password: 
Password again: 

As you can see, since Password field was marked as %confidential, the program prompts for an encryption password. This has nothing to do with the -r "Password: gmailpasswd" option given above. gmailpasswd is the value of the Password field as stored in the text file. The Password prompt asked by recins will encrypt the word gmailpasswd as shown below:

cat mysecrets.rec
%rec: PasswordDB
%key: Title
%sort: Title
%confidential: Password
%typedef: Date_t date
%type: Date Date_t
%auto: Date

Date: Sun, 05 Apr 2015 01:51:59 +0530
Title: Gmail
Username: myuser
URL: http://gmail.com
Comment: This is
+ an example of multiline comment.
+ It holds my Gmail secrets
Password: encrypted-CycHu08aE78gMvE4JIZ9kzVkiAQ=

All confidential fields will start with the word encrypted-. Also note how the Date field was populated automatically :) It is recommended that a single password be used for all confidential fields (i.e. the password you enter at the recins prompt acts as a file-password, which remains the same for all entries).

Reading the database

Selecting values in the database is performed by the recsel program.

In the simplest case, we specify an expression (-e) to match a certain criteria:

recsel -p Title,Artist -e "Title = 'Suprabhatam'" music.rec
Album: Venkatesha Suprabhatam
Artist: M.S. Subbulakshmi

Note that the string to match must be enclosed in single quotes. Recutils has the usual operators (<, >, =, !=, &&, ||, etc.) and operands (strings, numbers) for filtering data. Currently, there is no option to list all the fields and values matching the predicate; you must select the fields using a comma-separated list for -p.

recsel -t PasswordDB -p Username,Password mysecrets.rec 
Password: 
Username: myuser
Password: secret

In the first password prompt, you enter the file-level password that you gave during the recins invocation. The -p options prints those fields (Username and Password) from the PasswordDB.

Anyways, that’s all folks ! Hope this gave you a taste of Recutils and how easy it is to maintain records with it. Please read the entire GNU Recutils Manual for more detailed documentation.