Bug 460619

Summary:	Failed login with 32768 bit keys
Product:	[Fedora] Fedora	Reporter:	Nigel Jones <dev>
Component:	openssh	Assignee:	Tomas Mraz <tmraz>
Status:	CLOSED UPSTREAM	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	rawhide
Target Milestone:	---
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Hardware:	All
OS:	Linux
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Fixed In Version:		Doc Type:	Bug Fix
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Last Closed:	2008-08-29 06:59:01 UTC	Type:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Embargoed:

Description Nigel Jones 2008-08-29 04:43:55 UTC

Description of problem:
I am unable to login to a machine using a 32768bit SSH Key that is newly created, on both Rawhide systems and Red Hat EL-5 systems.

On Rawhide I get the following messages when trying to 'ssh localhost':

Aug 29 16:24:57 fantail sshd[4711]: Postponed publickey for njones from 127.0.0.1 port 45737 ssh2
Aug 29 16:25:08 fantail sshd[4710]: error: RSA_public_decrypt failed: error:04067069:lib(4):func(103):reason(105)

Version-Release number of selected component (if applicable):
openssh-5.1p1-2.fc10.x86_64

How reproducible:
Appears to be always (http://www.hermann-uwe.de/blog/creating-32768-bit-rsa-keys-for-fun-and-profit for an example on Debian)

Steps to Reproduce:
1. Generate a 32768 SSH Key
2. Load it into .ssh/authorized_keys
3. Attempt to login with said key
  
Actual results:
Error messages (per above) in /var/log/secure

Expected results:
Happy super-secure login :)

Additional info:
Yes I am mad, and creating the key was a joke, but it's a valid bug, SSH lets me generate such a key, but the key doesn't work, sounds like a bug to me.

Comment 1 Tomas Mraz 2008-08-29 06:59:01 UTC

There is a limit of 16384 on maximum length of modulus in RSA_public_decrypt which was added to resolve CVE-2006-2940.