diff --git a/contracts/src/main/kotlin/com/r3corda/contracts/asset/Cash.kt b/contracts/src/main/kotlin/com/r3corda/contracts/asset/Cash.kt
index 7a93ac0c03..a34cd9f158 100644
--- a/contracts/src/main/kotlin/com/r3corda/contracts/asset/Cash.kt
+++ b/contracts/src/main/kotlin/com/r3corda/contracts/asset/Cash.kt
@@ -8,6 +8,7 @@ import com.r3corda.core.contracts.clauses.*
 import com.r3corda.core.crypto.*
 import com.r3corda.core.node.services.Wallet
 import com.r3corda.core.utilities.Emoji
+import java.math.BigInteger
 import java.security.PublicKey
 import java.util.*
 
@@ -334,7 +335,7 @@ infix fun Cash.State.`with deposit`(deposit: PartyAndReference): Cash.State = wi
 // Unit testing helpers. These could go in a separate file but it's hardly worth it for just a few functions.
 
 /** A randomly generated key. */
-val DUMMY_CASH_ISSUER_KEY by lazy { generateKeyPair() }
+val DUMMY_CASH_ISSUER_KEY by lazy { entropyToKeyPair(BigInteger.valueOf(10)) }
 /** A dummy, randomly generated issuer party by the name of "Snake Oil Issuer" */
 val DUMMY_CASH_ISSUER by lazy { Party("Snake Oil Issuer", DUMMY_CASH_ISSUER_KEY.public).ref(1) }
 /** An extension property that lets you write 100.DOLLARS.CASH */
diff --git a/core/src/main/kotlin/com/r3corda/core/crypto/CryptoUtilities.kt b/core/src/main/kotlin/com/r3corda/core/crypto/CryptoUtilities.kt
index 1bace21711..f7682c03e2 100644
--- a/core/src/main/kotlin/com/r3corda/core/crypto/CryptoUtilities.kt
+++ b/core/src/main/kotlin/com/r3corda/core/crypto/CryptoUtilities.kt
@@ -5,10 +5,14 @@ import com.r3corda.core.serialization.OpaqueBytes
 import com.r3corda.core.serialization.SerializedBytes
 import com.r3corda.core.serialization.deserialize
 import net.i2p.crypto.eddsa.EdDSAEngine
+import net.i2p.crypto.eddsa.EdDSAPrivateKey
 import net.i2p.crypto.eddsa.EdDSAPublicKey
+import net.i2p.crypto.eddsa.KeyPairGenerator
+import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable
+import net.i2p.crypto.eddsa.spec.EdDSAPrivateKeySpec
+import net.i2p.crypto.eddsa.spec.EdDSAPublicKeySpec
 import java.math.BigInteger
 import java.security.*
-import net.i2p.crypto.eddsa.KeyPairGenerator as EddsaKeyPairGenerator
 
 fun newSecureRandom(): SecureRandom {
     if (System.getProperty("os.name") == "Linux") {
@@ -115,6 +119,7 @@ object NullPublicKey : PublicKey, Comparable<PublicKey> {
     override fun toString() = "NULL_KEY"
 }
 
+// TODO: Clean up this duplication between Null and Dummy public key
 class DummyPublicKey(val s: String) : PublicKey, Comparable<PublicKey> {
     override fun getAlgorithm() = "DUMMY"
     override fun getEncoded() = s.toByteArray()
@@ -125,6 +130,9 @@ class DummyPublicKey(val s: String) : PublicKey, Comparable<PublicKey> {
     override fun toString() = "PUBKEY[$s]"
 }
 
+/** A signature with a key and value of zero. Useful when you want a signature object that you know won't ever be used. */
+object NullSignature : DigitalSignature.WithKey(NullPublicKey, ByteArray(32))
+
 /** Utility to simplify the act of signing a byte array */
 fun PrivateKey.signWithECDSA(bits: ByteArray): DigitalSignature {
     val signer = EdDSAEngine()
@@ -163,10 +171,24 @@ fun PublicKey.toStringShort(): String {
     } ?: toString()
 }
 
+fun Iterable<PublicKey>.toStringsShort(): String = map { it.toStringShort() }.toString()
+
 // Allow Kotlin destructuring:    val (private, public) = keypair
 operator fun KeyPair.component1() = this.private
-
 operator fun KeyPair.component2() = this.public
 
 /** A simple wrapper that will make it easier to swap out the EC algorithm we use in future */
-fun generateKeyPair(): KeyPair = EddsaKeyPairGenerator().generateKeyPair()
+fun generateKeyPair(): KeyPair = KeyPairGenerator().generateKeyPair()
+
+/**
+ * Returns a keypair derived from the given private key entropy. This is useful for unit tests and other cases where
+ * you want hard-coded private keys.
+ */
+fun entropyToKeyPair(entropy: BigInteger): KeyPair {
+    val params = EdDSANamedCurveTable.getByName(EdDSANamedCurveTable.CURVE_ED25519_SHA512)
+    val bits = entropy.toByteArray().copyOf(params.curve.field.getb() / 8)
+    val priv = EdDSAPrivateKeySpec(bits, params)
+    val pub = EdDSAPublicKeySpec(priv.a, params)
+    val key = KeyPair(EdDSAPublicKey(pub), EdDSAPrivateKey(priv))
+    return key
+}
diff --git a/core/src/main/kotlin/com/r3corda/core/testing/CoreTestUtils.kt b/core/src/main/kotlin/com/r3corda/core/testing/CoreTestUtils.kt
index 704601cdec..1a80c1a024 100644
--- a/core/src/main/kotlin/com/r3corda/core/testing/CoreTestUtils.kt
+++ b/core/src/main/kotlin/com/r3corda/core/testing/CoreTestUtils.kt
@@ -7,14 +7,12 @@ import com.google.common.net.HostAndPort
 import com.r3corda.core.contracts.Attachment
 import com.r3corda.core.contracts.StateRef
 import com.r3corda.core.contracts.TransactionBuilder
-import com.r3corda.core.crypto.DummyPublicKey
-import com.r3corda.core.crypto.Party
-import com.r3corda.core.crypto.SecureHash
-import com.r3corda.core.crypto.generateKeyPair
+import com.r3corda.core.crypto.*
 import com.r3corda.core.node.services.IdentityService
 import com.r3corda.core.node.services.StorageService
 import com.r3corda.core.node.services.testing.MockIdentityService
 import com.r3corda.core.node.services.testing.MockStorageService
+import java.math.BigInteger
 import java.net.ServerSocket
 import java.security.KeyPair
 import java.security.PublicKey
@@ -73,7 +71,7 @@ val CHARLIE: Party get() = Party("Charlie", CHARLIE_PUBKEY)
 val MEGA_CORP: Party get() = Party("MegaCorp", MEGA_CORP_PUBKEY)
 val MINI_CORP: Party get() = Party("MiniCorp", MINI_CORP_PUBKEY)
 
-val DUMMY_NOTARY_KEY: KeyPair by lazy { generateKeyPair() }
+val DUMMY_NOTARY_KEY: KeyPair by lazy { entropyToKeyPair(BigInteger.valueOf(20)) }
 val DUMMY_NOTARY: Party get() = Party("Notary Service", DUMMY_NOTARY_KEY.public)
 
 val ALL_TEST_KEYS: List<KeyPair> get() = listOf(MEGA_CORP_KEY, MINI_CORP_KEY, ALICE_KEY, BOB_KEY, DUMMY_NOTARY_KEY)