62 lines
1.1 KiB
C
62 lines
1.1 KiB
C
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#include "os.h"
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#include <mp.h>
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#include <libsec.h>
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RSApriv*
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rsafill(mpint *n, mpint *e, mpint *d, mpint *p, mpint *q)
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{
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mpint *c2, *kq, *kp, *x;
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RSApriv *rsa;
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// make sure we're not being hoodwinked
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if(!probably_prime(p, 10) || !probably_prime(q, 10)){
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werrstr("rsafill: p or q not prime");
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return nil;
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}
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x = mpnew(0);
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mpmul(p, q, x);
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if(mpcmp(n, x) != 0){
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werrstr("rsafill: n != p*q");
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mpfree(x);
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return nil;
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}
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c2 = mpnew(0);
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mpsub(p, mpone, c2);
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mpsub(q, mpone, x);
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mpmul(c2, x, x);
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mpmul(e, d, c2);
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mpmod(c2, x, x);
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if(mpcmp(x, mpone) != 0){
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werrstr("rsafill: e*d != 1 mod (p-1)*(q-1)");
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mpfree(x);
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mpfree(c2);
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return nil;
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}
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// compute chinese remainder coefficient
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mpinvert(p, q, c2);
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// for crt a**k mod p == (a**(k mod p-1)) mod p
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kq = mpnew(0);
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kp = mpnew(0);
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mpsub(p, mpone, x);
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mpmod(d, x, kp);
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mpsub(q, mpone, x);
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mpmod(d, x, kq);
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rsa = rsaprivalloc();
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rsa->pub.ek = mpcopy(e);
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rsa->pub.n = mpcopy(n);
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rsa->dk = mpcopy(d);
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rsa->kp = kp;
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rsa->kq = kq;
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rsa->p = mpcopy(p);
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rsa->q = mpcopy(q);
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rsa->c2 = c2;
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mpfree(x);
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return rsa;
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}
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