63 lines
1.2 KiB
Go
63 lines
1.2 KiB
Go
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package ecdh
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import (
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"crypto"
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"io"
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"golang.org/x/crypto/curve25519"
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)
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type curve25519ECDH struct {
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ECDH
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}
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// NewCurve25519ECDH creates a new ECDH instance that uses djb's curve25519
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// elliptical curve.
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func NewCurve25519ECDH() ECDH {
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return &curve25519ECDH{}
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}
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func (e *curve25519ECDH) GenerateKey(rand io.Reader) (crypto.PrivateKey, crypto.PublicKey, error) {
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var pub, priv [32]byte
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var err error
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_, err = io.ReadFull(rand, priv[:])
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if err != nil {
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return nil, nil, err
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}
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priv[0] &= 248
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priv[31] &= 127
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priv[31] |= 64
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curve25519.ScalarBaseMult(&pub, &priv)
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return &priv, &pub, nil
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}
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func (e *curve25519ECDH) Marshal(p crypto.PublicKey) []byte {
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pub := p.(*[32]byte)
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return pub[:]
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}
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func (e *curve25519ECDH) Unmarshal(data []byte) (crypto.PublicKey, bool) {
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var pub [32]byte
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if len(data) != 32 {
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return nil, false
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}
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copy(pub[:], data)
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return &pub, true
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}
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func (e *curve25519ECDH) GenerateSharedSecret(privKey crypto.PrivateKey, pubKey crypto.PublicKey) ([]byte, error) {
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var priv, pub, secret *[32]byte
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priv = privKey.(*[32]byte)
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pub = pubKey.(*[32]byte)
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secret = new([32]byte)
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curve25519.ScalarMult(secret, priv, pub)
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return secret[:], nil
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}
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