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package otr3
import "math/big"
type smp struct {
state smpState
question *string
secret *big.Int
s1 *smp1State
s2 *smp2State
s3 *smp3State
}
const smpVersion = 1
func (s *smp) wipe() {
s.state = nil
s.question = nil
wipeBigInt(s.secret)
s.secret = nil
s.s1 = nil
s.s2 = nil
s.s3 = nil
}
func (s *smp) ensureSMP() {
if s.state != nil {
return
}
s.state = smpStateExpect1{}
}
// SMPQuestion returns the current SMP question and ok if there is one, and not ok if there isn't one.
func (c *Conversation) SMPQuestion() (string, bool) {
if c.smp.question == nil {
return "", false
}
return *c.smp.question, true
}
func generateSMPSecret(initiatorFingerprint, recipientFingerprint, ssid, secret []byte, v otrVersion) *big.Int {
h := v.hash2Instance()
h.Write([]byte{smpVersion})
h.Write(initiatorFingerprint)
h.Write(recipientFingerprint)
h.Write(ssid)
h.Write(secret)
return new(big.Int).SetBytes(h.Sum(nil))
}
func generateDZKP(r, a, c *big.Int) *big.Int {
return subMod(r, mul(a, c), q)
}
func generateZKP(r, a *big.Int, ix byte, v otrVersion) (c, d *big.Int) {
c = hashMPIsBN(v.hash2Instance(), ix, modExp(g1, r))
d = generateDZKP(r, a, c)
return
}
func verifyZKP(d, gen, c *big.Int, ix byte, v otrVersion) bool {
r := modExp(g1, d)
s := modExp(gen, c)
t := hashMPIsBN(v.hash2Instance(), ix, mulMod(r, s, p))
return eq(c, t)
}
func verifyZKP2(g2, g3, d5, d6, pb, qb, cp *big.Int, ix byte, v otrVersion) bool {
l := mulMod(
modExp(g3, d5),
modExp(pb, cp),
p)
r := mulMod(mul(modExp(g1, d5),
modExp(g2, d6)),
modExp(qb, cp),
p)
t := hashMPIsBN(v.hash2Instance(), ix, l, r)
return eq(cp, t)
}
func verifyZKP3(cp, g2, g3, d5, d6, pa, qa *big.Int, ix byte, v otrVersion) bool {
l := mulMod(modExp(g3, d5), modExp(pa, cp), p)
r := mulMod(mul(modExp(g1, d5), modExp(g2, d6)), modExp(qa, cp), p)
t := hashMPIsBN(v.hash2Instance(), ix, l, r)
return eq(cp, t)
}
func verifyZKP4(cr, g3a, d7, qaqb, ra *big.Int, ix byte, v otrVersion) bool {
l := mulMod(modExp(g1, d7), modExp(g3a, cr), p)
r := mulMod(modExp(qaqb, d7), modExp(ra, cr), p)
t := hashMPIsBN(v.hash2Instance(), ix, l, r)
return eq(cr, t)
}
func genSMPTLV(tp uint16, mpis ...*big.Int) tlv {
data := make([]byte, 0, 1000)
data = appendWord(data, uint32(len(mpis)))
data = appendMPIs(data, mpis...)
length := uint16(len(data))
out := tlv{
tlvType: tp,
tlvLength: length,
tlvValue: data,
}
return out
}
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