diff --git a/lib/ssh/src/ssh.hrl b/lib/ssh/src/ssh.hrl
index aecce6c1efea..5cf53b1b4b99 100644
--- a/lib/ssh/src/ssh.hrl
+++ b/lib/ssh/src/ssh.hrl
@@ -128,64 +128,80 @@
 -type open_socket()           :: gen_tcp:socket().
 
 -type subsystem_spec()        :: {Name::string(), mod_args()} .
-                              
+
 -type algs_list()             :: list( alg_entry() ).
--type alg_entry()             :: {kex, [kex_alg()]} 
+-type alg_entry()             :: {kex, [kex_alg()]}
                                | {public_key, [pubkey_alg()]}
                                | {cipher, double_algs(cipher_alg())}
                                | {mac, double_algs(mac_alg())}
                                | {compression, double_algs(compression_alg())} .
 
--type kex_alg()          :: 'diffie-hellman-group-exchange-sha1' |
-                            'diffie-hellman-group-exchange-sha256' |
-                            'diffie-hellman-group1-sha1' |
-                            'diffie-hellman-group14-sha1' |
-                            'diffie-hellman-group14-sha256' |
-                            'diffie-hellman-group16-sha512' |
-                            'diffie-hellman-group18-sha512' |
-                            'curve25519-sha256' |
-                            'curve25519-sha256@libssh.org' |
-                            'curve448-sha512' |
-                            'ecdh-sha2-nistp256' |
-                            'ecdh-sha2-nistp384' |
-                            'ecdh-sha2-nistp521'
-                            .
-
--type pubkey_alg()       :: 'ecdsa-sha2-nistp256' |
-                            'ecdsa-sha2-nistp384' |
-                            'ecdsa-sha2-nistp521' |
-                            'ssh-ed25519'  |
-                            'ssh-ed448'  |
-                            'rsa-sha2-256' |
-                            'rsa-sha2-512' |
-                            'ssh-dss' |
-                            'ssh-rsa'
-                            .
-
--type cipher_alg()       :: '3des-cbc' |
-                            'AEAD_AES_128_GCM' |
-                            'AEAD_AES_256_GCM' |
-                            'aes128-cbc' |
-                            'aes128-ctr' |
-                            'aes128-gcm@openssh.com' |
-                            'aes192-ctr' |
-                            'aes192-cbc' |
-                            'aes256-cbc' |
-                            'aes256-ctr' |
-                            'aes256-gcm@openssh.com' |
-                            'chacha20-poly1305@openssh.com'
-                            .
+-type kex_alg()  ::
+        'diffie-hellman-group-exchange-sha256' |
+        'diffie-hellman-group14-sha256' |
+        'diffie-hellman-group16-sha512' |
+        'diffie-hellman-group18-sha512' |
+        'curve25519-sha256' |
+        'curve25519-sha256@libssh.org' |
+        'curve448-sha512' |
+        'ecdh-sha2-nistp256' |
+        'ecdh-sha2-nistp384' |
+        'ecdh-sha2-nistp521' |
+        legacy_kex_alg().
+
+-type legacy_kex_alg()  ::
+        %%  Gone in OpenSSH 7.3.p1
+        'diffie-hellman-group1-sha1' |
+        %%  Gone in OpenSSH 8.2
+        'diffie-hellman-group14-sha1' |
+        'diffie-hellman-group-exchange-sha1'.
+
+-type pubkey_alg()  ::
+        'ecdsa-sha2-nistp256' |
+        'ecdsa-sha2-nistp384' |
+        'ecdsa-sha2-nistp521' |
+        'ssh-ed25519' |
+        'ssh-ed448' |
+        'rsa-sha2-256' |
+        'rsa-sha2-512'.
+
+-type legacy_pubkey_alg()  ::
+        'ssh-rsa' |
+        %% Gone in OpenSSH 7.3.p1:
+        'ssh-dss'.
+
+-type cipher_alg()  ::
+        'aes128-ctr' |
+        'aes128-gcm@openssh.com' |
+        'aes192-ctr' |
+        'aes256-ctr' |
+        'aes256-gcm@openssh.com' |
+        'chacha20-poly1305@openssh.com' |
+        legacy_cipher_alg()
+        .
 
--type mac_alg()          :: 'AEAD_AES_128_GCM' |
-                            'AEAD_AES_256_GCM' |
-                            'hmac-sha1' |
-                            'hmac-sha1-etm@openssh.com' |
-                            'hmac-sha1-96' |
-                            'hmac-sha2-256' |
-                            'hmac-sha2-512' |
-                            'hmac-sha2-256-etm@openssh.com' |
-                            'hmac-sha2-512-etm@openssh.com'
-                            .
+-type legacy_cipher_alg()  ::
+        'AEAD_AES_128_GCM' |
+        'AEAD_AES_256_GCM' |
+        %% Gone in OpenSSH 7.6
+        'aes128-cbc' |
+        'aes192-cbc' |
+        'aes256-cbc' |
+        '3des-cbc'.
+
+-type mac_alg()  ::
+        'hmac-sha1' |
+        'hmac-sha1-etm@openssh.com' |
+        'hmac-sha2-256' |
+        'hmac-sha2-512' |
+        'hmac-sha2-256-etm@openssh.com' |
+        'hmac-sha2-512-etm@openssh.com' |
+        legacy_mac_alg().
+
+-type legacy_mac_alg()  ::
+        'AEAD_AES_128_GCM' |
+        'AEAD_AES_256_GCM' |
+        'hmac-sha1-96'.
 
 -type compression_alg()  :: 'none' |
                             'zlib' |