NSS tools : signver¶

Name

signver — Verify a detached PKCS#7 signature for a file.

Synopsis

signtool -A | -V -d directory [-a] [-i input_file] [-o output_file] [-s

signature_file] [-v]

Description

The Signature Verification Tool, signver, is a simple command-line utility
that unpacks a base-64-encoded PKCS#7 signed object and verifies the
digital signature using standard cryptographic techniques. The Signature
Verification Tool can also display the contents of the signed object.

Options

-A

Displays all of the information in the PKCS#7 signature.

-V

Verifies the digital signature.

-d [sql:]directory

Specify the database directory which contains the certificates and
keys.
signver supports two types of databases: the legacy security
databases (cert8.db, key3.db, and secmod.db) and new SQLite
databases (cert9.db, key4.db, and pkcs11.txt). If the prefix sql:
is not used, then the tool assumes that the given databases are in
the old format.

-a

Sets that the given signature file is in ASCII format.

-i input_file

Gives the input file for the object with signed data.

-o output_file

Gives the output file to which to write the results.

-s signature_file

Gives the input file for the digital signature.

-v

Enables verbose output.

Extended Examples

Verifying a Signature

The -V option verifies that the signature in a given signature file is

valid when used to sign the given object (from the input file).

signver -V -s signature_file -i signed_file -d sql:/home/my/sharednssdb

signatureValid=yes

Printing Signature Data

The -A option prints all of the information contained in a signature file.
Using the -o option prints the signature file information to the given
output file rather than stdout.

signver -A -s signature_file -o output_file

NSS Database Types

NSS originally used BerkeleyDB databases to store security information.
The last versions of these legacy databases are:
o cert8.db for certificates
o key3.db for keys
o secmod.db for PKCS #11 module information
BerkeleyDB has performance limitations, though, which prevent it from
being easily used by multiple applications simultaneously. NSS has some
flexibility that allows applications to use their own, independent
database engine while keeping a shared database and working around the
access issues. Still, NSS requires more flexibility to provide a truly
shared security database.
In 2009, NSS introduced a new set of databases that are SQLite databases
rather than BerkleyDB. These new databases provide more accessibility and
performance:
o cert9.db for certificates
o key4.db for keys
o pkcs11.txt, which is listing of all of the PKCS #11 modules contained
in a new subdirectory in the security databases directory
Because the SQLite databases are designed to be shared, these are the
shared database type. The shared database type is preferred; the legacy
format is included for backward compatibility.
By default, the tools (certutil, pk12util, modutil) assume that the given
security databases follow the more common legacy type. Using the SQLite
databases must be manually specified by using the sql: prefix with the
given security directory. For example:

# signver -A -s signature -d sql:/home/my/sharednssdb

To set the shared database type as the default type for the tools, set the

NSS_DEFAULT_DB_TYPE environment variable to sql:

export NSS_DEFAULT_DB_TYPE=”sql”

This line can be set added to the ~/.bashrc file to make the change

permanent.

Most applications do not use the shared database by default, but they can

be configured to use them. For example, this how-to article covers how to

configure Firefox and Thunderbird to use the new shared NSS databases:

o https://wiki.mozilla.org/NSS_Shared_DB_Howto

For an engineering draft on the changes in the shared NSS databases, see

the NSS project wiki:

o https://wiki.mozilla.org/NSS_Shared_DB