54 lines
1.2 KiB
Go
54 lines
1.2 KiB
Go
package snell
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import (
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"crypto/aes"
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"crypto/cipher"
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"github.com/Dreamacro/go-shadowsocks2/shadowaead"
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"golang.org/x/crypto/argon2"
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"golang.org/x/crypto/chacha20poly1305"
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)
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type snellCipher struct {
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psk []byte
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keySize int
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makeAEAD func(key []byte) (cipher.AEAD, error)
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}
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func (sc *snellCipher) KeySize() int { return sc.keySize }
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func (sc *snellCipher) SaltSize() int { return 16 }
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func (sc *snellCipher) Encrypter(salt []byte) (cipher.AEAD, error) {
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return sc.makeAEAD(snellKDF(sc.psk, salt, sc.KeySize()))
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}
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func (sc *snellCipher) Decrypter(salt []byte) (cipher.AEAD, error) {
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return sc.makeAEAD(snellKDF(sc.psk, salt, sc.KeySize()))
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}
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func snellKDF(psk, salt []byte, keySize int) []byte {
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// snell use a special kdf function
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return argon2.IDKey(psk, salt, 3, 8, 1, 32)[:keySize]
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}
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func aesGCM(key []byte) (cipher.AEAD, error) {
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blk, err := aes.NewCipher(key)
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if err != nil {
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return nil, err
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}
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return cipher.NewGCM(blk)
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}
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func NewAES128GCM(psk []byte) shadowaead.Cipher {
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return &snellCipher{
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psk: psk,
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keySize: 16,
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makeAEAD: aesGCM,
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}
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}
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func NewChacha20Poly1305(psk []byte) shadowaead.Cipher {
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return &snellCipher{
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psk: psk,
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keySize: 32,
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makeAEAD: chacha20poly1305.New,
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}
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}
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