diff --git a/ssh-pubkey/ssh-pubkey b/ssh-pubkey/ssh-pubkey
old mode 100644
new mode 100755
index 010148a..12f899f
--- a/ssh-pubkey/ssh-pubkey
+++ b/ssh-pubkey/ssh-pubkey
@@ -2,6 +2,38 @@
 set -e
 set -u
 
+fn_warn_rsa() { (
+    echo 'WARNING'
+    echo '    ~/.ssh/id_rsa is less than the required 3072 bits'
+    echo '    (some modern services will reject your key)'
+
+    echo ''
+    echo 'SOLUTION'
+    echo '    Generate a new key, and update accordingly'
+
+    my_ts="$(date -u "+%F_%H.%M.%S")"
+
+    echo ''
+    echo '    # OPTION 1: Generate a more efficient, ED25519 256-bit key'
+    echo '    #           and update your ~/.ssh/config accordingly'
+    echo "    mv ~/.ssh/id_rsa ~/.ssh/id_rsa.${my_ts}.bak"
+    # shellcheck disable=SC2016
+    echo '    ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519 -q -N ""'
+    echo "    echo 'Host *
+        IdentityFile ~/.ssh/id_ed25519
+        IdentityFile ~/.ssh/id_rsa.${my_ts}.bak' >> ~/.ssh/config"
+
+    echo ''
+    echo '    # OPTION 2: Generate a larger, 4096-bit RSA key"'
+    echo '    #           and update your ~/.ssh/config accordingly'
+    echo "    mv ~/.ssh/id_rsa ~/.ssh/id_rsa.${my_ts}.bak"
+    # shellcheck disable=SC2016
+    echo '    ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_rsa -q -N ""'
+    echo "    echo 'Host *
+        IdentityFile ~/.ssh/id_rsa
+        IdentityFile ~/.ssh/id_rsa.${my_ts}.bak' >> ~/.ssh/config"
+); }
+
 main() {
 
     if ! test -d ~/.ssh; then
@@ -20,25 +52,49 @@ main() {
         chmod 0600 ~/.ssh/authorized_keys
     fi
 
-    if ! test -f ~/.ssh/id_rsa; then
-        ssh-keygen -b 2048 -t rsa -f ~/.ssh/id_rsa -q -N ""
+    my_keytype=''
+    if test -f ~/.ssh/id_ed25519; then
+        my_keytype='ed25519'
+        if ! test -f ~/.ssh/id_ed25519.pub; then
+            echo >&2 ""
+            ssh-keygen -y -f ~/.ssh/id_ed25519 > ~/.ssh/id_ed25519.pub
+        fi
+    elif test -f ~/.ssh/id_rsa; then
+        my_keytype='rsa'
+        if ! test -f ~/.ssh/id_rsa.pub; then
+            echo >&2 ""
+            ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub
+        fi
+    elif test -f ~/.ssh/id_ecda; then
+        my_keytype='ecdsa'
+        if ! test -f ~/.ssh/id_ecdsa.pub; then
+            echo >&2 ""
+            ssh-keygen -y -f ~/.ssh/id_ecda > ~/.ssh/id_ecda.pub
+        fi
+    else
+        my_keytype='rsa'
         echo >&2 ""
-    fi
-
-    if ! test -f ~/.ssh/id_rsa.pub; then
+        ssh-keygen -b 4096 -t rsa -f ~/.ssh/id_rsa -q -N ""
         ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub
-        echo >&2 ""
     fi
 
     # TODO use the comment (if any) for the name of the file
     echo >&2 ""
     #shellcheck disable=SC2088
-    echo >&2 "~/Downloads/id_rsa.$(whoami).pub":
+    echo >&2 "~/Downloads/id_${my_keytype}.$(whoami).pub":
     echo >&2 ""
-    rm -f "$HOME/Downloads/id_rsa.$(whoami).pub"
-    cp -RPp "$HOME/.ssh/id_rsa.pub" "$HOME/Downloads/id_rsa.$(whoami).pub"
-    cat "$HOME/Downloads/id_rsa.$(whoami).pub"
+    rm -f "$HOME/Downloads/id_${my_keytype}.$(whoami).pub"
+    cp -RPp "$HOME/.ssh/id_${my_keytype}.pub" "$HOME/Downloads/id_${my_keytype}.$(whoami).pub"
+    cat "$HOME/Downloads/id_${my_keytype}.$(whoami).pub"
     echo >&2 ""
+
+    if test -f ~/.ssh/id_rsa; then
+        my_rsa_size="$(wc < ~/.ssh/id_rsa | rev | cut -d' ' -f1 | rev)"
+        if test "${my_rsa_size}" -lt 2500; then
+            fn_warn_rsa >&2
+            echo >&2 ""
+        fi
+    fi
 }
 
 main