39 lines
1.6 KiB
Text
39 lines
1.6 KiB
Text
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lifelinestyle ::solid
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participantspacing 10
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participant :0 " " as p0
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lifelinestyle p0 #white
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actor "Alice" as A
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participant :0 " " as p1
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lifelinestyle p1 #white
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actor "Bob" as B
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participant :0 " " as p2
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lifelinestyle p2 #white
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parallel
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box over A: ""//R[0]//"" = ""HKDF(0, //S//)""
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box over B: ""//R[0]//"" = ""HKDF(0, //S//)""
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parallel off
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box over A: generate new ratchet keypair ""//T[0]//""
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A->B: ""//R[0]//(//msg0//)"", ""//T[0]//""
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A->B: ""//R[0]//(//msg1//)"", ""//T[0]//""
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A->B: ""//R[0]//(//msg2//)"", ""//T[0]//""
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box over B: generate new ratchet keypair ""//T[1]//""
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box over B: ""//R[1]//"" = ""HKDF(//R[0]//, DH(//T[1]//, //T[0]//))""
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B->A: ""//R[1]//(//msg3//)"", ""//T[1]//""
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box over A: ""//R[1]//"" = ""HKDF(//R[0]//, DH(//T[0]//, //T[1]//))""
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B->A: ""//R[1]//(//msg4//)"", ""//T[1]//""
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B->(13)A: ""//R[1]//(//msg5//)"", ""//T[1]//""
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space -14
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box over A: generate new ratchet keypair ""//T[2]//""
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box over A: ""//R[2]//"" = ""HKDF(//R[1]//, DH(//T[2]//, //T[1]//))""
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A->(3)B: ""//R[2]//(//msg6//)"", ""//T[2]//""
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box over B: ""//R[2]//"" = ""HKDF(//R[1]//, DH(//T[1]//, //T[2]//))""
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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]//""
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