30 lines
519 B
C
30 lines
519 B
C
#include "os.h"
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#include <mp.h>
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#include <libsec.h>
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int
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egverify(EGpub *pub, EGsig *sig, mpint *m)
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{
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mpint *p = pub->p, *alpha = pub->alpha;
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mpint *r = sig->r, *s = sig->s;
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mpint *v1, *v2, *rs;
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int rv = -1;
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if(mpcmp(r, mpone) < 0 || mpcmp(r, p) >= 0)
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return rv;
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v1 = mpnew(0);
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rs = mpnew(0);
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v2 = mpnew(0);
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mpexp(pub->key, r, p, v1);
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mpexp(r, s, p, rs);
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mpmul(v1, rs, v1);
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mpmod(v1, p, v1);
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mpexp(alpha, m, p, v2);
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if(mpcmp(v1, v2) == 0)
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rv = 0;
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mpfree(v1);
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mpfree(rs);
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mpfree(v2);
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return rv;
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}
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