55 lignes
1 017 o
Go
55 lignes
1 017 o
Go
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package nosurf
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import (
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"crypto/rand"
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"io"
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)
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// Masks/unmasks the given data *in place*
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// with the given key
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// Slices must be of the same length, or oneTimePad will panic
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func oneTimePad(data, key []byte) {
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n := len(data)
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if n != len(key) {
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panic("Lengths of slices are not equal")
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}
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for i := 0; i < n; i++ {
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data[i] ^= key[i]
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}
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}
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func maskToken(data []byte) []byte {
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if len(data) != tokenLength {
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return nil
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}
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// tokenLength*2 == len(enckey + token)
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result := make([]byte, 2*tokenLength)
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// the first half of the result is the OTP
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// the second half is the masked token itself
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key := result[:tokenLength]
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token := result[tokenLength:]
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copy(token, data)
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// generate the random token
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if _, err := io.ReadFull(rand.Reader, key); err != nil {
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panic(err)
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}
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oneTimePad(token, key)
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return result
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}
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func unmaskToken(data []byte) []byte {
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if len(data) != tokenLength*2 {
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return nil
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}
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key := data[:tokenLength]
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token := data[tokenLength:]
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oneTimePad(token, key)
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return token
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}
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