#11793 deprecated legacy ciphers for conch

docs/conch/man/conch.1

@@ -108,7 +108,7 @@ Enable compression.
 .It Fl c Ar cipher_spec
 Selects encryption algorithms to be used for this connection, as a comma-separated list of ciphers in order of preference.  The list that
 .Nm
-supports is (in order of default preference): aes256-ctr, aes256-cbc, aes192-ctr, aes192-cbc, aes128-ctr, aes128-cbc, cast128-ctr, cast128-cbc, blowfish-ctr, blowfish, idea-ctr, idea-cbc, 3des-ctr, 3des-cbc.
+supports is (in order of default preference): aes256-ctr, aes256-cbc, aes192-ctr, aes192-cbc, aes128-ctr, aes128-cbc, 3des-ctr, 3des-cbc.
 .It Fl e Ar ch | ^ch | none
 Sets the escape character for sessions with a PTY (default:
 .Ql ~ ) .

src/twisted/conch/ssh/transport.py

@@ -94,17 +94,13 @@ class SSHCiphers:
 
     cipherMap = {
         b"3des-cbc": (algorithms.TripleDES, 24, modes.CBC),
-        b"blowfish-cbc": (algorithms.Blowfish, 16, modes.CBC),
         b"aes256-cbc": (algorithms.AES, 32, modes.CBC),
         b"aes192-cbc": (algorithms.AES, 24, modes.CBC),
         b"aes128-cbc": (algorithms.AES, 16, modes.CBC),
-        b"cast128-cbc": (algorithms.CAST5, 16, modes.CBC),
         b"aes128-ctr": (algorithms.AES, 16, modes.CTR),
         b"aes192-ctr": (algorithms.AES, 24, modes.CTR),
         b"aes256-ctr": (algorithms.AES, 32, modes.CTR),
         b"3des-ctr": (algorithms.TripleDES, 24, modes.CTR),
-        b"blowfish-ctr": (algorithms.Blowfish, 16, modes.CTR),
-        b"cast128-ctr": (algorithms.CAST5, 16, modes.CTR),
         b"none": (None, 0, modes.CBC),
     }
     macMap = {
@@ -284,10 +280,6 @@ def _getSupportedCiphers():
         b"aes192-cbc",
         b"aes128-ctr",
         b"aes128-cbc",
-        b"cast128-ctr",
-        b"cast128-cbc",
-        b"blowfish-ctr",
-        b"blowfish-cbc",
         b"3des-ctr",
         b"3des-cbc",
     ]

src/twisted/newsfragments/11793.removal

@@ -0,0 +1 @@
+Twisted Conch has removed and no longer supports legacy ciphers (CAST5, SEED, IDEA, Blowfish) as the upstream library "cryptography" has deprecated them since version 37.