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DH ratchet sequence diagram

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Richard van der Hoff 2020-11-23 18:31:08 +00:00
parent 11d34f79af
commit b9771dae61
2 changed files with 40 additions and 0 deletions
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lifelinestyle ::solid
participantspacing 10
participant :0 " " as p0
lifelinestyle p0 #white
actor "Alice" as A
participant :0 " " as p1
lifelinestyle p1 #white
actor "Bob" as B
participant :0 " " as p2
lifelinestyle p2 #white
parallel
box over A: ""//R[0]//"" = ""HKDF(0, //S//)""
box over B: ""//R[0]//"" = ""HKDF(0, //S//)""
parallel off
box over A: generate new ratchet keypair ""//T[0]//""
A->B: ""//R[0]//(//msg0//)"", ""//T[0]//""
A->B: ""//R[0]//(//msg1//)"", ""//T[0]//""
A->B: ""//R[0]//(//msg2//)"", ""//T[0]//""
box over B: generate new ratchet keypair ""//T[1]//""
box over B: ""//R[1]//"" = ""HKDF(//R[0]//, DH(//T[1]//, //T[0]//))""
B->A: ""//R[1]//(//msg3//)"", ""//T[1]//""
box over A: ""//R[1]//"" = ""HKDF(//R[0]//, DH(//T[0]//, //T[1]//))""
B->A: ""//R[1]//(//msg4//)"", ""//T[1]//""
B->(13)A: ""//R[1]//(//msg5//)"", ""//T[1]//""
space -14
box over A: generate new ratchet keypair ""//T[2]//""
box over A: ""//R[2]//"" = ""HKDF(//R[1]//, DH(//T[2]//, //T[1]//))""
A->(3)B: ""//R[2]//(//msg6//)"", ""//T[2]//""
box over B: ""//R[2]//"" = ""HKDF(//R[1]//, DH(//T[1]//, //T[2]//))""
box over p0,p2 #EDF2AE:<size:10>where:\n ""//S//"" is the shared secret derived from the 3ECDH exchange\n ""//R[n]//"" is a root key\n ""//T[n]//"" is a ratchet keypair\n ""HKDF(//salt//, //key//)"" means performing an HMAC-based key derivation with a salt value of ""//salt//"" and input key material of ""//key//""\n ""DH(//k1//, //k2//)"" means performing Diffie-Hellman with the private half of ""//k1//"" and the public half of ""//k2//""\n ""//R[n]//(//msg//)"" means a message encrypted with a key derived from root key ""//R[n]//""