diff --git a/Cargo.lock b/Cargo.lock
index 5c9f21f..808912b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -289,6 +289,22 @@ version = "1.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c2db04e74f0a9a93103b50e90b96024c9b2bdca8bce6a632ec71b88736d3d359"
 
+[[package]]
+name = "dsa"
+version = "0.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48bc224a9084ad760195584ce5abb3c2c34a225fa312a128ad245a6b412b7689"
+dependencies = [
+ "digest",
+ "num-bigint-dig",
+ "num-traits",
+ "pkcs8",
+ "rfc6979",
+ "sha2",
+ "signature",
+ "zeroize",
+]
+
 [[package]]
 name = "ecdsa"
 version = "0.16.9"
@@ -1155,9 +1171,9 @@ dependencies = [
 
 [[package]]
 name = "spin"
-version = "0.9.8"
+version = "0.9.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
+checksum = "3763264f6b73151db08c50ff20d7d8a0b8796e021cdea7ceedad07b80155fa0e"
 
 [[package]]
 name = "spki"
@@ -1235,6 +1251,7 @@ version = "0.6.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3b86f5297f0f04d08cabaa0f6bff7cb6aec4d9c3b49d87990d63da9d9156a8c3"
 dependencies = [
+ "dsa",
  "ed25519-dalek",
  "num-bigint-dig",
  "p256",
@@ -1243,6 +1260,7 @@ dependencies = [
  "rand_core",
  "rsa",
  "sec1",
+ "sha1",
  "sha2",
  "signature",
  "ssh-cipher",
diff --git a/Cargo.toml b/Cargo.toml
index 1575731..2d64a7f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -27,16 +27,21 @@ tokio = { version = "1", optional = true, features = ["rt", "net", "time"] }
 tokio-util = { version = "0.7", optional = true, features = ["codec"] }
 service-binding = { version = "^3", optional = true }
 ssh-encoding = { version = "0.2" }
-ssh-key = { version = "0.6", features = ["crypto", "alloc"] }
+ssh-key = { version = "0.6", default-features = false, features = ["std"] }
 thiserror = "2"
 subtle = { version = "2", default-features = false }
 signature = { version = "2", features = ["alloc"] }
 secrecy = "0.10"
 
 [features]
-default = ["agent"]
-codec = ["tokio-util"]
-agent = ["futures", "log", "tokio", "async-trait", "codec", "service-binding"]
+default = ["agent", "crypto-all"]
+codec = ["dep:tokio-util"]
+crypto-all = ["ssh-key/crypto", "crypto-dsa", "crypto-ecdsa", "crypto-ed25519", "crypto-rsa"]
+crypto-dsa = ["ssh-key/dsa"]
+crypto-ecdsa = ["ssh-key/p256", "ssh-key/p384", "ssh-key/p521"]
+crypto-ed25519 = ["ssh-key/ed25519"]
+crypto-rsa = ["ssh-key/rsa"]
+agent = ["dep:futures", "dep:log", "dep:tokio", "dep:async-trait", "codec", "dep:service-binding"]
 
 [dev-dependencies]
 env_logger = "0.11.10"
diff --git a/src/lib.rs b/src/lib.rs
index 3e66c40..56c52cd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,8 @@
-#![doc = include_str!("../README.md")]
+#![cfg_attr(feature = "default", doc = include_str!("../README.md"))]
+#![cfg_attr(
+    not(feature = "default"),
+    doc = "Documentation available using the default feature"
+)]
 #![deny(missing_debug_implementations)]
 #![deny(unsafe_code)]
 #![deny(missing_docs)]
diff --git a/src/proto/extension/message.rs b/src/proto/extension/message.rs
index aca12e2..cb77ce8 100644
--- a/src/proto/extension/message.rs
+++ b/src/proto/extension/message.rs
@@ -130,6 +130,7 @@ impl MessageExtension for SessionBind {
 }
 
 #[cfg(test)]
+#[cfg(feature = "crypto-ed25519")]
 mod tests {
     use testresult::TestResult;