* Remove the stream ciphers
The unauthenticated stream ciphers (aes-*-cfb, aes-*-ctr, camellia-*-cfb,
chacha20, chacha20-ietf, salsa20) are gone from every build, together
with the SS_ENABLE_LEGACY option, the C++ stream codecs, their C test
oracle and the stream-only tests and configurations. A configuration
naming one of them, or RC4/table, now fails at startup with a message
pointing to an AEAD method, and test_cli checks that.
Shell completions list only the supported methods (and now include the
2022 ones), and the docs and the compatibility contract say the stream
ciphers were removed.
* Drop the Mbed TLS CFB requirement and stale stream-cipher examples
CFB was only needed by the removed stream ciphers, so a system Mbed TLS
built without it no longer fails to configure. The public header example
now uses aes-256-gcm.
Add `ss-local --printable-salt` / `"printable_salt": true`, disabled by
default. For each outgoing TCP salt it picks a prefix length uniformly
from 6-12 bytes and samples those bytes as printable ASCII (0x20-0x7e)
immediately before key derivation. The salt stays 32 bytes with no
framing or markers, so the wire format is unchanged and any stock
server interoperates. Only chacha20-ietf-poly1305 and aes-256-gcm are
accepted; other ciphers fail at startup. UDP, server responses, and
AEAD-2022 are untouched.
Crypto unit tests cover length distribution, empty first writes, exact
framing overhead, salt-tail preservation, byte-at-a-time decryption,
tampering and replay rejection. CLI tests check local-only exposure and
cipher rejection via flag, config key and bad config type. interop.py
gains --printable-salt and --server-bin for independent stock servers.
docs/printable-salt.md records the design, entropy bound, fingerprint
caveats and route-experiment procedure; docs/encoding-experiments.md
and tests/experiments/ hold the Base85/lowpop85/TLS outer-transport
prototypes. docs/measurements/printable-salt-2026-09-23/ archives the
sanitized results of the aborted field trials.
Co-authored-by: Claude <noreply@anthropic.com>
Max Lv
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