[Cryptography Team] Reading ssh pub/private keys

[Bert Freudenberg]

Thanks Rob, I'll try that (provided I find the  
DSAPrivateKeyFileReader class).

I'm not implementing ssh, but the OLPC happens to use that file  
format for their per-user keys. So rather than generating our own  
(via SecurityManager>>generateLocalKeyPair) which takes a rather long  
time on that slow machine, I'd rather just load that.

- Bert -

On Mar 29, 2007, at 15:33 , Robert Withers wrote:

> Bert, there are indeed Base64 encoded.  For starters, you can try:
>
> 	(DSAPrivateKeyFileReader fromFile: privateKeyFileName) asPrivateKey
>
> I am not sure about the publicKey, but you could try the same  
> reader code.  Internally, it strips off the PEM markings (----- 
> BEGIN DSA...and so on), the does a Base64 decode and leaves you  
> with bytes.  The #asPrivateKey will take those bytes and do an ASN. 
> 1 decode on them.  My point is that the PublicKey may also be ASN.1  
> encoded, so you may find some traction here.
>
> Let me know how it goes.
>
> Are you implementing SSH?!
>
> cheers,
> Robert
>
> On Mar 29, 2007, at 6:23 AM, Bert Freudenberg wrote:
>
>> Hi folks,
>>
>> I have an ssh-format keypair and would like to extract the  
>> (p,q,g,x) and (p,q,g,y) DSA tuples from that. The private key  
>> looks like this:
>>
>> -----BEGIN DSA PRIVATE KEY-----
>> MIIBuwIB..............XCIa3cIp
>> -----END DSA PRIVATE KEY-----
>>
>> and the public key:
>>
>> ssh-dss AAAAB3NzaC1k.........nNEnWCasjXraVA==
>>
>> So this looks like Base64-encoded numbers, but how are they  
>> encoded? The only reference I found was this:
>>
>> http://www.openssh.com/txt/draft-ietf-secsh-publickeyfile-02.txt
>>
>> But it does not detail how the "binary blob" translates to DSA  
>> tuples.
>>
>> - Bert -
>>
>>
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