matrix-spec/proposals/xxxx-sas-v2.md
2020-05-11 11:54:50 -04:00

37 lines
1.3 KiB
Markdown

# SAS verification, v2
## Proposal
A new `key_agreement_protocol`, `curve25519-hkdf-sha256` is introduced. It is
the same as `curve25519` except that the info parameter for the HKDF is the
concatenation of:
* The string `MATRIX_KEY_VERIFICATION_SAS|`.
* The Matrix ID of the user who sent the `m.key.verification.start` message,
followed by `|`.
* The Device ID of the device which sent the `m.key.verification.start`
message, followed by `|`.
* The public key from the `m.key.verification.key` message sent by the device
which sent the `m.key.verification.start` message, followed by `|`.
* The Matrix ID of the user who sent the `m.key.verification.accept` message,
followed by `|`.
* The Device ID of the device which sent the `m.key.verification.accept`
message, followed by `|`.
* The public key from the `m.key.verification.key` message sent by the device
which sent the `m.key.verification.accept` message, followed by `|`.
* The `transaction_id` being used.
The differences from `curve25519` are the addition of the public keys, and the
addition of `|` as delimiter between the fields.
The `key_agreement_protocol` `curve25519` is deprecated and may be removed in
the future.
## Potential issues
## Alternatives
## Security considerations
## Unstable prefix