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authorsiddharth ravikumar <s@ricketyspace.net>2022-06-12 16:48:58 -0400
committersiddharth ravikumar <s@ricketyspace.net>2022-06-12 16:48:58 -0400
commitcdb98133c282ee2fb51430001ad0bd8ee8328f7e (patch)
treec31f159d5c9ef9d87cf74fe64a02ed22c6c9dca5 /lib/srp.go
parent400b1906499083e1cac0ce2432ff66b69b925b2f (diff)
lib: add handling for simplified srp
Diffstat (limited to 'lib/srp.go')
-rw-r--r--lib/srp.go83
1 files changed, 83 insertions, 0 deletions
diff --git a/lib/srp.go b/lib/srp.go
index aa3a956..892ba8c 100644
--- a/lib/srp.go
+++ b/lib/srp.go
@@ -173,6 +173,21 @@ func (u *SRPUser) EphemeralKeyPub() (*big.Int, error) {
return pub, nil
}
+func (u *SRPUser) EphemeralKeyPubSimple() (*big.Int, error) {
+ if u.g == nil || u.g.Cmp(big.NewInt(0)) != 1 {
+ return nil, CPError{"g is not initialized"}
+ }
+ if u.b == nil || u.b.Cmp(big.NewInt(0)) != 1 {
+ return nil, CPError{"b is not initialized"}
+ }
+
+ // pub is 'B'
+ pub := new(big.Int)
+ pub.Exp(u.g, u.b, u.n)
+
+ return pub, nil
+}
+
func (u *SRPUser) SetScramblingParam(a *big.Int) error {
b, err := u.EphemeralKeyPub()
if err != nil {
@@ -202,6 +217,22 @@ func (u *SRPUser) SetScramblingParam(a *big.Int) error {
return nil
}
+func (u *SRPUser) SetScramblingParamSimple() error {
+ // random 128-bits
+ r, err := RandomBytes(16)
+ if err != nil {
+ return err
+ }
+
+ // Set scrambling paramter u
+ u.u = new(big.Int)
+ u.u.SetBytes(r)
+ if u.u.Cmp(big.NewInt(0)) != 1 {
+ return CPError{"u is invalid"}
+ }
+ return nil
+}
+
func (u *SRPUser) ComputeSessionKey(a *big.Int) error {
// v^u
vu := new(big.Int)
@@ -346,6 +377,20 @@ func (s *SRPClientSession) SetScramblingParam(b *big.Int) error {
return nil
}
+func (s *SRPClientSession) SetScramblingParamSimple(u []byte) error {
+ if len(u) < 16 {
+ return CPError{"server u is invalid"}
+ }
+
+ // Set scrambling paramter u
+ s.u = new(big.Int)
+ s.u.SetBytes(u)
+ if s.u.Cmp(big.NewInt(0)) != 1 {
+ return CPError{"u is invalid"}
+ }
+ return nil
+}
+
func (s *SRPClientSession) ComputeSessionKey(salt []byte,
pass string, b *big.Int) error {
if len(salt) < 1 {
@@ -396,6 +441,44 @@ func (s *SRPClientSession) ComputeSessionKey(salt []byte,
return nil
}
+func (s *SRPClientSession) ComputeSessionKeySimple(salt []byte,
+ pass string, b *big.Int) error {
+ if len(salt) < 1 {
+ return CPError{"salt invalid"}
+ }
+
+ // salt+pass
+ sp := make([]byte, 0)
+ copy(sp, salt)
+ sp = append(sp, StrToBytes(pass)...)
+
+ // x = H(salt+pass)
+ x := new(big.Int)
+ s.h.Message(sp)
+ x.SetBytes(s.h.Hash())
+
+ // u * x
+ ux := new(big.Int)
+ ux.Mul(s.u, x)
+
+ // a + u*x
+ aux := new(big.Int)
+ aux.Add(s.a, ux)
+
+ // S = (B) ^ (a + u*x)
+ sec := new(big.Int)
+ sec.Exp(b, aux, s.n)
+ sb := sec.Bytes()
+
+ // K = H(S)
+ m := make([]byte, 0)
+ m = append(m, sb...)
+ s.h.Message(m)
+ s.sk = s.h.Hash()
+
+ return nil
+}
+
func (s *SRPClientSession) SetSessionKey(key []byte) {
s.sk = key
}