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