diff --git a/runtime-sdk/src/crypto/signature/sr25519.rs b/runtime-sdk/src/crypto/signature/sr25519.rs
index bab1905eac..e845e497a6 100644
--- a/runtime-sdk/src/crypto/signature/sr25519.rs
+++ b/runtime-sdk/src/crypto/signature/sr25519.rs
@@ -69,3 +69,68 @@ impl From<&'static str> for PublicKey {
         PublicKey::from_bytes(&base64::decode(s).unwrap()).unwrap()
     }
 }
+
+/// A memory-backed signer for Sr25519.
+pub struct MemorySigner {
+    kp: schnorrkel::Keypair,
+}
+
+impl MemorySigner {
+    /// Creates a new signer from a seed.
+    pub fn new_from_seed(seed: &[u8]) -> Result<Self, Error> {
+        let sk =
+            schnorrkel::MiniSecretKey::from_bytes(&seed).map_err(|_| Error::InvalidArgument)?;
+        let kp = sk.expand_to_keypair(schnorrkel::keys::ExpansionMode::Ed25519);
+        Ok(Self { kp })
+    }
+
+    /// Generates a new signer deterministically from a test key name string.
+    pub fn new_test(name: &str) -> Self {
+        let mut digest = Sha512Trunc256::new();
+        digest.update(name.as_bytes());
+        let seed = digest.finalize();
+
+        Self::new_from_seed(&seed).unwrap()
+    }
+
+    /// Public key corresponding to the signer.
+    pub fn public(&self) -> PublicKey {
+        PublicKey::from_bytes(&self.kp.public.to_bytes()).unwrap()
+    }
+
+    /// Generates a signature with the private key over the context and message.
+    pub fn context_sign(&self, context: &[u8], message: &[u8]) -> Result<Signature, Error> {
+        // Convert the context to a Sr25519 SigningContext.
+        let context = schnorrkel::context::SigningContext::new(context);
+
+        // Generate a SigningTranscript from the context, and a pre-hash
+        // of the message.
+        //
+        // Note: This requires using Sha512Trunc256 instead of our hash,
+        // due to the need for FixedOutput.
+        let mut digest = Sha512Trunc256::new();
+        digest.update(message);
+        let transcript = context.hash256(digest);
+
+        let signature = self.kp.sign(transcript);
+
+        Ok(signature.to_bytes().to_vec().into())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_memory_signer() {
+        let signer = MemorySigner::new_test("memory signer test");
+        let ctx = b"oasis-core/test: context";
+        let message = b"this is a message";
+        let signature = signer.context_sign(ctx, message).unwrap();
+        let pk = signer.public();
+
+        pk.verify(ctx, message, &signature)
+            .expect("signature should verify");
+    }
+}
diff --git a/runtime-sdk/src/testing/keys.rs b/runtime-sdk/src/testing/keys.rs
index 3d0723b306..33c17faf94 100644
--- a/runtime-sdk/src/testing/keys.rs
+++ b/runtime-sdk/src/testing/keys.rs
@@ -1,10 +1,8 @@
 //! Module that contains known test keys.
 
-// TODO: Should be derived from seeds once implemented in the Rust version.
-
 /// Define an ed25519 test key.
 macro_rules! test_key_ed25519 {
-    ($doc:expr, $name:ident, $pk:expr) => {
+    ($doc:expr, $name:ident, $seed:expr) => {
         #[doc = " Test key "]
         #[doc=$doc]
         #[doc = "."]
@@ -25,7 +23,14 @@ macro_rules! test_key_ed25519 {
             #[doc=$doc]
             #[doc = "."]
             pub fn pk_ed25519() -> ed25519::PublicKey {
-                $pk.into()
+                signer().public()
+            }
+
+            #[doc = " Test Ed25519 signer "]
+            #[doc=$doc]
+            #[doc = "."]
+            pub fn signer() -> ed25519::MemorySigner {
+                ed25519::MemorySigner::new_test($seed)
             }
 
             #[doc = " Test address derivation information "]
@@ -90,7 +95,7 @@ macro_rules! test_key_secp256k1 {
 
 /// Define an sr25519 test key.
 macro_rules! test_key_sr25519 {
-    ($doc:expr, $name:ident, $pk:expr) => {
+    ($doc:expr, $name:ident, $seed:expr) => {
         #[doc = " Test key "]
         #[doc=$doc]
         #[doc = "."]
@@ -111,7 +116,14 @@ macro_rules! test_key_sr25519 {
             #[doc=$doc]
             #[doc = "."]
             pub fn pk_sr25519() -> sr25519::PublicKey {
-                $pk.into()
+                signer().public()
+            }
+
+            #[doc = " Test Sr25519 signer "]
+            #[doc=$doc]
+            #[doc = "."]
+            pub fn signer() -> sr25519::MemorySigner {
+                sr25519::MemorySigner::new_test($seed)
             }
 
             #[doc = " Test address derivation information "]
@@ -131,10 +143,11 @@ macro_rules! test_key_sr25519 {
     };
 }
 
-test_key_ed25519!("A", alice, "NcPzNW3YU2T+ugNUtUWtoQnRvbOL9dYSaBfbjHLP1pE=");
-test_key_ed25519!("B", bob, "YgkEiVSR4SMQdfXw+ppuFYlqH0seutnCKk8KG8PyAx0=");
-test_key_ed25519!("C", charlie, "8l1AQE+ETOPLckiNJ7NOD+AfZdaPw6wguir/vSF11YI=");
-test_key_secp256k1!("D", dave, "AwF6GNjbybMzhi3XRj5R1oTiMMkO1nAwB7NZAlH1X4BE");
-test_key_secp256k1!("E", erin, "A9i0oSK+5sLSONbMYGmaFUA+Fb8zzqYEMUMspacIgO09");
-test_key_sr25519!("F", frank, "ljm9ZwdAldhlyWM2B4C+3gQZis+ceaxnt6QA4rOcP0k=");
-test_key_sr25519!("G", grace, "0MHrNhjVTOFWmsOgpWcC3L8jIX3ZatKr0/yxMPtwckc=");
+test_key_ed25519!("Alice", alice, "oasis-runtime-sdk/test-keys: alice");
+test_key_ed25519!("Bob", bob, "oasis-runtime-sdk/test-keys: bob");
+test_key_ed25519!("Charlie", charlie, "oasis-runtime-sdk/test-keys: charlie");
+test_key_ed25519!("Cory", cory, "ekiden test entity key seed");
+test_key_secp256k1!("Dave", dave, "AwF6GNjbybMzhi3XRj5R1oTiMMkO1nAwB7NZAlH1X4BE");
+test_key_secp256k1!("Erin", erin, "A9i0oSK+5sLSONbMYGmaFUA+Fb8zzqYEMUMspacIgO09");
+test_key_sr25519!("Frank", frank, "oasis-runtime-sdk/test-keys: frank");
+test_key_sr25519!("Grace", grace, "oasis-runtime-sdk/test-keys: grace");