39 lines
822 B
Go
39 lines
822 B
Go
package rfc6979
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import (
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"crypto/ecdsa"
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"hash"
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"math/big"
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)
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// SignECDSA signs an arbitrary length hash (which should be the result of
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// hashing a larger message) using the private key, priv. It returns the
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// signature as a pair of integers.
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//
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// Will panic if invalid private key (>N for the curve) is passed.
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func SignECDSA(priv *ecdsa.PrivateKey, hash []byte, alg func() hash.Hash) (r, s *big.Int) {
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c := priv.Curve
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N := c.Params().N
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generateSecret(N, priv.D, alg, hash, func(k *big.Int, e *big.Int, t []byte) bool {
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k.FillBytes(t)
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r, _ = priv.ScalarBaseMult(t)
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r.Mod(r, N)
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if r.Sign() == 0 {
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return false
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}
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inv := k.ModInverse(k, N)
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s = new(big.Int).Mul(priv.D, r)
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s.Add(s, e)
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s.Mul(s, inv)
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s.Mod(s, N)
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return s.Sign() != 0
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})
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return
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}
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