mirror of https://github.com/gtank/merlin
62 lines
1.6 KiB
Go
62 lines
1.6 KiB
Go
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package merlin
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import (
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"encoding/binary"
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"fmt"
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"github.com/mimoo/StrobeGo/strobe"
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)
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const (
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merlinProtocolLabel = "Merlin v1.0"
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domainSeparatorLabel = "dom-sep"
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)
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type Transcript struct {
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s strobe.Strobe
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}
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func NewTranscript(appLabel string) *Transcript {
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t := Transcript{
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s: strobe.InitStrobe(merlinProtocolLabel, 128),
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}
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fmt.Printf("Initialize STROBE-128(%x)\n", merlinProtocolLabel)
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t.AppendMessage([]byte(domainSeparatorLabel), []byte(appLabel))
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return &t
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}
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// Append adds the message to the transcript with the supplied label.
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func (t *Transcript) AppendMessage(label, message []byte) {
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// AD[label || le32(len(message))](message)
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sizeBuffer := make([]byte, 4)
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binary.LittleEndian.PutUint32(sizeBuffer[0:], uint32(len(message)))
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fmt.Printf("meta-AD : %x || LE32(%d)\t# b\"%s\"\n", label, len(message), label)
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t.s.AD(true, label)
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t.s.AD(true, sizeBuffer)
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fmt.Printf("AD : %x\t# b\"%s\"\n", message, message)
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t.s.AD(false, message)
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}
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// ExtractBytes fills the supplied buffer with the verifier's challenge bytes.
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// The label parameter is metadata about the challenge, and is also appended to
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// the transcript. See the Transcript Protocols section of the Merlin website
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// for details on labels.
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func (t *Transcript) ExtractBytes(label []byte, outLen int) []byte {
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sizeBuffer := make([]byte, 4)
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binary.LittleEndian.PutUint32(sizeBuffer[0:], uint32(outLen))
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fmt.Printf("meta-AD : %x || LE32(%d)\t# b\"%s\"\n", label, outLen, label)
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t.s.AD(true, label)
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t.s.AD(true, sizeBuffer)
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// a PRF call directly to the output buffer would be better
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return t.s.PRF(outLen)
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}
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