45 lines
956 B
Go
45 lines
956 B
Go
package cryptocore
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import (
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"bytes"
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"crypto/rand"
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"encoding/binary"
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"encoding/hex"
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"fmt"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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// RandBytes gets "n" random bytes from /dev/urandom or panics
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func RandBytes(n int) []byte {
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b := make([]byte, n)
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_, err := rand.Read(b)
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if err != nil {
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panic("Failed to read random bytes: " + err.Error())
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}
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return b
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}
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// RandUint64 returns a secure random uint64
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func RandUint64() uint64 {
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b := RandBytes(8)
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return binary.BigEndian.Uint64(b)
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}
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type nonceGenerator struct {
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lastNonce []byte
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nonceLen int // bytes
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}
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// Get a random "nonceLen"-byte nonce
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func (n *nonceGenerator) Get() []byte {
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nonce := RandBytes(n.nonceLen)
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tlog.Debug.Printf("nonceGenerator.Get(): %s\n", hex.EncodeToString(nonce))
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if bytes.Equal(nonce, n.lastNonce) {
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m := fmt.Sprintf("Got the same nonce twice: %s. This should never happen!", hex.EncodeToString(nonce))
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panic(m)
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}
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n.lastNonce = nonce
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return nonce
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}
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