25 lines
651 B
Go
25 lines
651 B
Go
package pnet
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import (
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"golang.org/x/crypto/salsa20"
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"golang.org/x/crypto/sha3"
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)
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var zero64 = make([]byte, 64)
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func fingerprint(psk *[32]byte) []byte {
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enc := make([]byte, 64)
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// We encrypt data first so we don't feed PSK to hash function.
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// Salsa20 function is not reversible thus increasing our security margin.
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salsa20.XORKeyStream(enc, zero64, []byte("finprint"), psk)
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out := make([]byte, 16)
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// Then do Shake-128 hash to reduce its length.
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// This way if for some reason Shake is broken and Salsa20 preimage is possible,
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// attacker has only half of the bytes necessary to recreate psk.
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sha3.ShakeSum128(out, enc)
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return out
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}
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