Hi Brett, I’m not sure I understand your question completely, so let me try to describe it and you can correct me where I get it wrong.
You have some deployment system which uses a Ruby process to replace tokens in
a flow template with the “real” values, and one of the values that needs to be
set is the password used by an EncryptContent processor configured with
password-based encryption. (This much makes sense to me).
What I am confused by is your reference to “hash values”. While in many
situations (most web applications, user databases, etc.) cryptographic hashing
is the correct way to protect a password or other sensitive value when
persisting to disk, this is only appropriate if the raw sensitive value does
not need to be retrieved. However, in this scenario, the password must be
usable in raw form to derive the key to encrypt content, so it cannot be stored
in a “hash value” format (irreversible), but rather encrypted (reversible).
In order to persist the encrypted form of this password, you need to run the
same encryption algorithm and use the same key as NiFi does. These are exposed
to you in nifi.properties using the keys “nifi.sensitive.props.key” and
“nifi.sensitive.props.algorithm”. By default the key is blank, and the
algorithm is “PBEWITHMD5AND256BITAES-CBC-OPENSSL” — in English, that’s
Password-Based Encryption using a single iteration of MD5 digest over the
password (the previous property) and salt (none in this case), taking the
resulting 32 hexadecimal characters (16 bytes) as the first half of a 256 bit
(32 byte) key, then calculating the MD5 of this value concatenated with the raw
password and raw salt again as the second half. [1][2] That key is now used
with AES-256 in CBC mode [3] to encrypt the raw sensitive values and persist
them in the form “enc{hex-encoded-ciphertext}” in the flow (see below for
example). If you feel at this point that the default key derivation function is
not sufficiently strong, know that I agree with you and have opened a Jira to
increase the strength of this process [4].
Anyway, to answer (what I believe is your question), you can write Ruby code to
populate your template with the encrypted value by retrieving the sensitive
properties key from nifi.properties, use the Ruby OpenSSL bindings [5] to
derive the key and encrypt the password, and then encode it in hexadecimal and
wrap it with the “enc{“ and “}” tags.
I would also suggest you look at the Variable Registry [6][7], upcoming
encrypted configuration files [8], and deterministic templates [9][10], as
these may provide an easier way to perform what you are looking for, or at
least inform your next steps if you wish to keep your Ruby template system and
move forward in a compatible manner.
If this didn’t answer your question (or raised others), please reply and I’ll
filter my thoughts through someone with a more human understanding of the
system.
[1] https://www.openssl.org/docs/manmaster/crypto/EVP_BytesToKey.html
<https://www.openssl.org/docs/manmaster/crypto/EVP_BytesToKey.html>
[2] http://security.stackexchange.com/a/117654/16485
[3]
https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Block_Chaining_.28CBC.29
<https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Block_Chaining_.28CBC.29>
[4] https://issues.apache.org/jira/browse/NIFI-1465
<https://issues.apache.org/jira/browse/NIFI-1465>
[5] http://ruby-doc.org/stdlib-2.0.0/libdoc/openssl/rdoc/OpenSSL.html
<http://ruby-doc.org/stdlib-2.0.0/libdoc/openssl/rdoc/OpenSSL.html>
[6] https://cwiki.apache.org/confluence/display/NIFI/Variable+Registry
[7] https://github.com/apache/nifi/pull/571
[8] https://issues.apache.org/jira/browse/NIFI-1831
[9]
https://cwiki.apache.org/confluence/display/NIFI/Configuration+Management+of+Flows
<https://cwiki.apache.org/confluence/display/NIFI/Configuration+Management+of+Flows>
<processor>
<id>206f32b5-9f72-4762-a1d5-711f8669db60</id>
<name>EncryptContent</name>
<position x="1101.0" y="176.0"/>
<styles/>
<comment/>
<class>org.apache.nifi.processors.standard.EncryptContent</class>
...
<property>
<name>Encryption Algorithm</name>
<value>AES_GCM</value>
</property>
<property>
<name>Password</name>
<value>enc{3832072F21CB7448E3C268287AF7F2F38359EB7F7E0F22CCFF2432EBC358335A0616B5CDCC895827FE0B1478901D364A}</value>
</property>
</processor>
Andy LoPresto
[email protected]
[email protected]
PGP Fingerprint: 70EC B3E5 98A6 5A3F D3C4 BACE 3C6E F65B 2F7D EF69
> On Jul 14, 2016, at 1:23 PM, Hite, Brett <[email protected]> wrote:
>
> Hello,
>
> I have a flow file that is created from a Ruby template file (flow.xml.erb).
> The template contains variables that the user can set that then get populated
> when NiFi is set up. I have an EncryptContent processor and would like to
> create a template variable for the Password property. Ideally, the user would
> say “password = some_password” and the template variable would evaluate to
> the hash value stored in the actual flow file.
>
> Is there a way that I can calculate the hash value given a plain text
> password? I’ve looked around and haven’t found too much. The NiFi
> Administration Guide has an Encryption Configuration section that doesn’t
> quite answer my question.
>
> Thanks,
>
> Brett Hite
> [email protected] <mailto:[email protected]>
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