[asterisk-bugs] [JIRA] Created: (ASTERISK-20219) IAX2 Call Encryption Fails with RSA authentication

[Michael Munger (JIRA)]

IAX2 Call Encryption Fails with RSA authentication
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                 Key: ASTERISK-20219
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-20219
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
          Components: Channels/chan_iax2
    Affects Versions: 1.8.14.1, 1.8.11.1
         Environment: Server A
Asterisk Version: Asterisk 1.8.14.1
Platform: Ubuntu 9.10 Server

Server B
Asterisk Version: Asterisk 1.8.11-cert4
Platform: Ubuntu 10.04.4 LTS
            Reporter: Michael Munger
            Severity: Minor
         Attachments: iax2rsabug.tar.gz

When using RSA and key encryption for peering two servers together, the peers are able to authenticate using RSA encryption; however, call encryption fails with RSA encryption. In the attached debug information, please find documentation of the problem. (Wireshark frame numbers are appended to each even in parenthesis)

1. ServerB (oshea) makes a NEW request message to initiate the call. (#60)

2. Accordingly, ServerA (highpoweredhelp) replies with an AUTHREQ. The AUTHREQ DOES contain the username and authentication IE's as specified in rfc5456 6.2.7. (#63)

3. ServerB (oshea) replies with an RSA Challenge Result in an AUTHREP message. (#65)

4. ServerA then sends an ACK (#67)

5. ServerA immediatley sends a REJECT message with a "No authority found" cause. (#68)

Notes:
Given that the two peers are able to authenticate and register using these keys, the keys are deemed to be valid. In fact, if we remove forceencryption=yes and retain encryption=aes128 from iax.conf on both sides, the calls are authenticated using RSA and processed normally. However, despite having encryption=aes128, the calls are not encrypted: call information containing IP addresses of local stations as well as well identified voice packets are capturable with wireshark (tshark was used in this environment), and could be re-assembled into playable voice calls.

Changing the configs to use auth=md5 instead of auth=rsa immediately fixes the problem with no other configurations, and also encrypts the calls properly.

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