57 lines
923 B
Go
57 lines
923 B
Go
package cryptfs
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import (
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"encoding/binary"
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"encoding/hex"
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"sync"
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"crypto/rand"
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)
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type nonce96 struct {
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lock sync.Mutex
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high32 uint32
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low64 uint64
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ready int
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}
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var gcmNonce nonce96
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// Get "n" random bytes from /dev/urandom or panic
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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("Could not get random bytes for nonce")
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}
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return b
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}
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func (n *nonce96) init() {
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b := RandBytes(8)
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n.low64 = binary.BigEndian.Uint64(b)
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b = RandBytes(4)
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n.high32 = binary.BigEndian.Uint32(b)
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n.ready = 1
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return
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}
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func (n *nonce96) Get() []byte {
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n.lock.Lock()
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if n.ready == 0 {
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n.init()
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}
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n.low64++
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if n.low64 == 0 {
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// Counter has wrapped
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n.high32++
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}
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r := make([]byte, 12)
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binary.BigEndian.PutUint32(r[0:4], n.high32)
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binary.BigEndian.PutUint64(r[4:12], n.low64)
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n.lock.Unlock()
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Debug.Printf("nonce96.Get(): %s\n", hex.EncodeToString(r))
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return r
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}
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