Re: [netconf] crypto-types fallback strategy

[Per Hedeland <[e-mail]>]

On 2019-09-18 22:29, Schönwälder, Jürgen wrote:
> On Wed, Sep 18, 2019 at 10:06:38PM +0200, Martin Bjorklund wrote:
>> Kent Watsen <[e-mail]> wrote:
>>> [moving Russ and Sean to BCC, per Rich's action]
>>>
>>>
>>>
>>>> Minor: Does the string in the description above mean ASCII string
>>>> or binary string, RFC 4251 seemingly uses both definitions?
>>>
>>> I don't know, but this is the language found for the "key-data" leaf
>>> in RFC 7317 (i.e., we've been living with this definition for awhile)
>>
>> So the definition is:
>>
>>               leaf key-data {
>>                 type binary;
>>                 mandatory true;
>>                 description
>>                   "The binary public key data for this SSH key, as
>>                    specified by RFC 4253, Section 6.6, i.e.:
>>
>>                      string    certificate or public key format
>>                                identifier
>>                      byte[n]   key/certificate data.";
>>
>> The textual representation of a binary in YANG is base64 encoded.  As
>> it happens, this is exactly the same as OpenSSH uses for its keys.  So
>> the open ssh key can be copy/pasted into the NC/RC XML/JSON.
>>
> 
> My public ssh keys usually start like this:
> 
>    ssh-rsa AAAA...
> 
> Looking at RFC 4251, it seems to me that 'string' is encoded with a
> length prefix, followed by n bytes of key data. This means the start
> in hex would be something like this:
> 
>    00 00 00 07 73 73 68 2d 72 73 61
> 
> If I base64 encode this, I won't get what I quoted above.

Are you sure? I don't have a handy base64 encoder for "space-separated
octets represented as hex numbers", but going in the other direction
with the initial part of my public ssh key (ssh-rsa), using the Linux
'base64' command and converting the result to "space-separated octets
represented as hex numbers" gives:

$ echo AAAAB3NzaC1yc2EA | base64 -d | od -t x1
0000000 00 00 00 07 73 73 68 2d 72 73 61 00

Seems to agree with what you have.

--Per