On Fri, 30 May 2014 [email protected] wrote:
> diff --git a/Securing_TLS/en-US/OpenSSL.xml b/Securing_TLS/en-US/OpenSSL.xml
> index 191564f..df458d9 100644
> --- a/Securing_TLS/en-US/OpenSSL.xml
> +++ b/Securing_TLS/en-US/OpenSSL.xml
> @@ -160,5 +160,36 @@ EXP-KRB5-RC4-MD5 SSLv3
> </para>
> </section>
> </section>
> + <section
> id="sect-Fedora_Security_Team-Securing_TLS-OpenSSL-Generating_Crypto">
> + <title>Generating Crypto</title>
> + <para>Properly generating keys and certificates is as important
> as the ciphers suite being used to secure the circuit. The best cipher can
> be broken with improperly generated keys.</para>
> +
> + <section
> id="sect-Fedora_Security_Team-Securing_TLS-OpenSSL-Generating_Crypto-RSA">
> + <title>Generating RSA keys</title>
> + <para>RSA keys are the most common key type used to
> secure SSL and TLS circuits. It's relatively simple to generate keys and
> we'll describe how and why now.</para>
> + <para>
> +<screen>
> +openssl genrsa -aes128 -out key_name.key 3072
> +</screen>
> +This will generate a 3072-bit RSA key that is sufficently large for true 128
> bits of security. To obtain 256 bits of security the RSA key will need to be
> 15360 bits. If you require that type of security, however, a ECDSA key
> should be utilized.
> +<important><para>The industry standard 2048-bit RSA key only provides 112
> bits of security.<footnote><para>NIST SP 800-57 Part 1, Rev 3 <ulink
> url="http://csrc.nist.gov/publications/nistpubs/800-57/sp800-57_part1_rev3_general.pdf";
> /></para></footnote></para></important>
etc... but "OpenSSL pitfalls" in defensive-coding/en-US/Features-TLS.xml
warns that
OpenSSL command-line commands, such as <command>openssl
genrsa</command>, do not ensure that physical entropy is used
for key generation--they obtain entropy from
<filename>/dev/urandom</filename> and other sources, but not
from <filename>/dev/random</filename>. This can result in
weak keys if the system lacks a proper entropy source (e.g., a
virtual machine with solid state storage). Depending on local
policies, keys generated by these OpenSSL tools should not be
used in high-value, critical functions.
I think such warning (and perhaps an advice to use -randfile /dev/random?)
should be reflected in documents telling people to use openssl genrsa et
al. to generate keys.
Come to think of it, maybe it would also be a good idea to patch these
commands to print the warning when they are used to generate new keys
without a good source of entropy.
--
Pavel Kankovsky aka Peak "Que sais-je?"
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