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| -rw-r--r-- | doc/doc-txt/experimental-spec.txt | 52 |
1 files changed, 32 insertions, 20 deletions
diff --git a/doc/doc-txt/experimental-spec.txt b/doc/doc-txt/experimental-spec.txt index feecb3375..f5f72f551 100644 --- a/doc/doc-txt/experimental-spec.txt +++ b/doc/doc-txt/experimental-spec.txt @@ -966,34 +966,46 @@ calculation and one full packet roundtrip time. Operational cost/benefit: The extra data being transmitted costs a minor amount, and the client has -extra costs in storing and retrieving the data. + extra costs in storing and retrieving the data. -In the Exim/Gnutls implementation the extra cost on an initial connection -which is TLS1.2 over a loopback path is about 6ms on 2017-laptop class hardware. -The saved cost on a subsequent connection is about 4ms; three or more -connections become a net win. On longer network paths, two or more -connections will have an average lower startup time thanks to the one -saved packet roundtrip. TLS1.3 will save the crypto cpu costs but not any -packet roundtrips. + In the Exim/Gnutls implementation the extra cost on an initial connection + which is TLS1.2 over a loopback path is about 6ms on 2017-laptop class hardware. + The saved cost on a subsequent connection is about 4ms; three or more + connections become a net win. On longer network paths, two or more + connections will have an average lower startup time thanks to the one + saved packet roundtrip. TLS1.3 will save the crypto cpu costs but not any + packet roundtrips. + + Since a new hints DB is used, the hints DB maintenance should be updated + to additionally handle "tls". Security aspects: The session ticket is encrypted, but is obviously an additional security -vulnarability surface. An attacker able to decrypt it would have access -all connections using the resumed session. -The session ticket encryption key is not committed to storage by the server -and is rotated regularly. Tickets have limited lifetime. + vulnarability surface. An attacker able to decrypt it would have access + all connections using the resumed session. + The session ticket encryption key is not committed to storage by the server + and is rotated regularly. Tickets have limited lifetime. -There is a question-mark over the security of the Diffie-Helman parameters -used for session negotiation. TBD. q-value; cf bug 1895 + There is a question-mark over the security of the Diffie-Helman parameters + used for session negotiation. TBD. q-value; cf bug 1895 Observability: New log_selector "tls_resumption", appends an asterisk to the tls_cipher "X=" -element. - -Variables $tls_{in,out}_resumption have bit 0-4 indicating respectively -support built, client requested ticket, client offered session, -server issued ticket, resume used. A suitable decode list is provided -in the builtin macro _RESUME_DECODE for ${listextract {}{}}. + element. + + Variables $tls_{in,out}_resumption have bit 0-4 indicating respectively + support built, client requested ticket, client offered session, + server issued ticket, resume used. A suitable decode list is provided + in the builtin macro _RESUME_DECODE for ${listextract {}{}}. + +Issues: + In a resumed session: + $tls_{in,out}_{certificate_verified,{peer,our}cert} will be unset + verify = certificate will be false + $tls_{in,out}_cipher will have values different to the original + $tls_{in,out}_bits (is unspecified) + $tls_{in,out}_ocsp will be "not requested" + $tls_{in,out}_peerdn will be unset -------------------------------------------------------------- |