Month: February 2024
ClientHello 2 – Secrets and Keys in TLS 1.3
Listing 12.2: ClientHello message structure uint16 ProtocolVersion;opaque Random[32];uint8 CipherSuite[2]; /* Cryptographic suite selector */struct { ProtocolVersion legacy_version = 0x0303; /* TLS v1.2 */ Random random; opaque legacy_session_id<0..32>; CipherSuite cipher_suites<2..2^16-2>; opaque legacy_compression_methods<1..2^8-1>; Extension extensions<8..2^16-1>;} ClientHello; In turned out, however, that the implementation of TLS version negotiation was flawed in many TLS servers. As a result, servers would reject a well-formed ClientHello message…
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12.6.2 ClientHello According to TLS specification, ClientHello must be the first message Bob sends to Alice. Bob must also send ClientHello if Alice has responded with HelloRetryRequest message because of a mismatch in their cryptographic parameters. In the latter case, Bob must respond with the same ClientHello message, altering only specific parameter values. If HelloRetryRequest…
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