forked from quic-go/quic-go
80 lines
1.9 KiB
Go
80 lines
1.9 KiB
Go
package crypto
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import (
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"bytes"
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"errors"
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"fmt"
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"hash/fnv"
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"github.com/lucas-clemente/quic-go/internal/protocol"
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)
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// nullAEAD handles not-yet encrypted packets
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type nullAEADFNV128a struct {
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perspective protocol.Perspective
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}
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var _ AEAD = &nullAEADFNV128a{}
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// Open and verify the ciphertext
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func (n *nullAEADFNV128a) Open(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) ([]byte, error) {
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if len(src) < 12 {
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return nil, errors.New("NullAEAD: ciphertext cannot be less than 12 bytes long")
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}
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hash := fnv.New128a()
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hash.Write(associatedData)
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hash.Write(src[12:])
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if n.perspective == protocol.PerspectiveServer {
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hash.Write([]byte("Client"))
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} else {
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hash.Write([]byte("Server"))
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}
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sum := make([]byte, 0, 16)
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sum = hash.Sum(sum)
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// The tag is written in little endian, so we need to reverse the slice.
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reverse(sum)
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if !bytes.Equal(sum[:12], src[:12]) {
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return nil, fmt.Errorf("NullAEAD: failed to authenticate received data (%#v vs %#v)", sum[:12], src[:12])
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}
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return src[12:], nil
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}
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// Seal writes hash and ciphertext to the buffer
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func (n *nullAEADFNV128a) Seal(dst, src []byte, packetNumber protocol.PacketNumber, associatedData []byte) []byte {
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if cap(dst) < 12+len(src) {
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dst = make([]byte, 12+len(src))
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} else {
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dst = dst[:12+len(src)]
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}
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hash := fnv.New128a()
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hash.Write(associatedData)
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hash.Write(src)
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if n.perspective == protocol.PerspectiveServer {
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hash.Write([]byte("Server"))
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} else {
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hash.Write([]byte("Client"))
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}
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sum := make([]byte, 0, 16)
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sum = hash.Sum(sum)
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// The tag is written in little endian, so we need to reverse the slice.
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reverse(sum)
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copy(dst[12:], src)
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copy(dst, sum[:12])
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return dst
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}
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func (n *nullAEADFNV128a) Overhead() int {
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return 12
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}
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func reverse(a []byte) {
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for left, right := 0, len(a)-1; left < right; left, right = left+1, right-1 {
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a[left], a[right] = a[right], a[left]
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}
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}
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