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/*
* SSH RSA authentication.
*
* Client protocol:
* read public key
* if you don't like it, read another, repeat
* write challenge
* read response
* all numbers are hexadecimal biginits parsable with strtomp.
*/
#include "dat.h"
enum {
CHavePub,
CHaveResp,
Maxphase,
};
static char *phasenames[] = {
[CHavePub] "CHavePub",
[CHaveResp] "CHaveResp",
};
struct State
{
RSApriv *priv;
mpint *resp;
int off;
Key *key;
};
static RSApriv*
readrsapriv(Key *k)
{
char *a;
RSApriv *priv;
priv = rsaprivalloc();
if((a=strfindattr(k->attr, "ek"))==nil || (priv->pub.ek=strtomp(a, nil, 16, nil))==nil)
goto Error;
if((a=strfindattr(k->attr, "n"))==nil || (priv->pub.n=strtomp(a, nil, 16, nil))==nil)
goto Error;
if((a=strfindattr(k->privattr, "!p"))==nil || (priv->p=strtomp(a, nil, 16, nil))==nil)
goto Error;
if((a=strfindattr(k->privattr, "!q"))==nil || (priv->q=strtomp(a, nil, 16, nil))==nil)
goto Error;
if((a=strfindattr(k->privattr, "!kp"))==nil || (priv->kp=strtomp(a, nil, 16, nil))==nil)
goto Error;
if((a=strfindattr(k->privattr, "!kq"))==nil || (priv->kq=strtomp(a, nil, 16, nil))==nil)
goto Error;
if((a=strfindattr(k->privattr, "!c2"))==nil || (priv->c2=strtomp(a, nil, 16, nil))==nil)
goto Error;
if((a=strfindattr(k->privattr, "!dk"))==nil || (priv->dk=strtomp(a, nil, 16, nil))==nil)
goto Error;
return priv;
Error:
rsaprivfree(priv);
return nil;
}
static int
sshrsainit(Proto*, Fsstate *fss)
{
int iscli;
State *s;
if((iscli = isclient(strfindattr(fss->attr, "role"))) < 0)
return failure(fss, nil);
if(iscli==0)
return failure(fss, "sshrsa server unimplemented");
s = emalloc(sizeof *s);
fss->phasename = phasenames;
fss->maxphase = Maxphase;
fss->phase = CHavePub;
fss->ps = s;
return RpcOk;
}
static int
sshrsaread(Fsstate *fss, void *va, uint *n)
{
RSApriv *priv;
State *s;
s = fss->ps;
switch(fss->phase){
default:
return phaseerror(fss, "read");
case CHavePub:
if(s->key){
closekey(s->key);
s->key = nil;
}
if((s->key = findkey(fss, Kuser, nil, s->off, fss->attr, nil)) == nil)
return failure(fss, nil);
s->off++;
priv = s->key->priv;
*n = snprint(va, *n, "%B", priv->pub.n);
return RpcOk;
case CHaveResp:
*n = snprint(va, *n, "%B", s->resp);
fss->phase = Established;
return RpcOk;
}
}
static int
sshrsawrite(Fsstate *fss, void *va, uint)
{
mpint *m;
State *s;
s = fss->ps;
switch(fss->phase){
default:
return phaseerror(fss, "write");
case CHavePub:
if(s->key == nil)
return failure(fss, "no current key");
m = strtomp(va, nil, 16, nil);
m = rsadecrypt(s->key->priv, m, m);
s->resp = m;
fss->phase = CHaveResp;
return RpcOk;
}
}
static void
sshrsaclose(Fsstate *fss)
{
State *s;
s = fss->ps;
if(s->key)
closekey(s->key);
if(s->resp)
mpfree(s->resp);
free(s);
}
static int
sshrsaaddkey(Key *k)
{
fmtinstall('B', mpconv);
if((k->priv = readrsapriv(k)) == nil){
werrstr("malformed key data");
return -1;
}
return replacekey(k);
}
static void
sshrsaclosekey(Key *k)
{
rsaprivfree(k->priv);
}
Proto sshrsa = {
.name= "sshrsa",
.init= sshrsainit,
.write= sshrsawrite,
.read= sshrsaread,
.close= sshrsaclose,
.addkey= sshrsaaddkey,
.closekey= sshrsaclosekey,
};
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