diff --git a/aezeed/cipherseeed_test.go b/aezeed/cipherseeed_test.go
new file mode 100644
index 00000000..a6215059
--- /dev/null
+++ b/aezeed/cipherseeed_test.go
@@ -0,0 +1,513 @@
+package aezeed
+
+import (
+	"bytes"
+	"math/rand"
+	"testing"
+	"testing/quick"
+	"time"
+)
+
+var (
+	testEntropy = [EntropySize]byte{
+		0x81, 0xb6, 0x37, 0xd8,
+		0x63, 0x59, 0xe6, 0x96,
+		0x0d, 0xe7, 0x95, 0xe4,
+		0x1e, 0x0b, 0x4c, 0xfd,
+	}
+)
+
+func assertCipherSeedEqual(t *testing.T, cipherSeed *CipherSeed,
+	cipherSeed2 *CipherSeed) {
+
+	if cipherSeed.InternalVersion != cipherSeed2.InternalVersion {
+		t.Fatalf("mismatched versions: expected %v, got %v",
+			cipherSeed.InternalVersion, cipherSeed2.InternalVersion)
+	}
+	if cipherSeed.Birthday != cipherSeed2.Birthday {
+		t.Fatalf("mismatched birthday: expected %v, got %v",
+			cipherSeed.Birthday, cipherSeed2.Birthday)
+	}
+	if cipherSeed.Entropy != cipherSeed2.Entropy {
+		t.Fatalf("mismatched versions: expected %x, got %x",
+			cipherSeed.Entropy[:], cipherSeed2.Entropy[:])
+	}
+}
+
+func TestAezeedVersion0TestVectors(t *testing.T) {
+	t.Parallel()
+
+	// TODO(roasbeef):
+}
+
+// TestEmptyPassphraseDerivation tests that the aezeed scheme is able to derive
+// a proper mnemonic, and decipher that mnemonic when the user uses an empty
+// passphrase.
+func TestEmptyPassphraseDerivation(t *testing.T) {
+	t.Parallel()
+
+	// Our empty passphrase...
+	pass := []byte{}
+
+	// We'll now create a new cipher seed with an internal version of zero
+	// to simulate a wallet that just adopted the scheme.
+	cipherSeed, err := New(0, &testEntropy, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// Now that the seed has been created, we'll attempt to convert it to a
+	// valid mnemonic.
+	mnemonic, err := cipherSeed.ToMnemonic(pass)
+	if err != nil {
+		t.Fatalf("unable to create mnemonic: %v", err)
+	}
+
+	// Next, we'll try to decrypt the mnemonic with the passphrase that we
+	// used.
+	cipherSeed2, err := mnemonic.ToCipherSeed(pass)
+	if err != nil {
+		t.Fatalf("unable to decrypt mnemonic: %v", err)
+	}
+
+	// Finally, we'll ensure that the uncovered cipher seed matches
+	// precisely.
+	assertCipherSeedEqual(t, cipherSeed, cipherSeed2)
+}
+
+// TestManualEntropyGeneration tests that if the user doesn't provide a source
+// of entropy, then we do so ourselves.
+func TestManualEntropyGeneration(t *testing.T) {
+	t.Parallel()
+
+	// Our empty passphrase...
+	pass := []byte{}
+
+	// We'll now create a new cipher seed with an internal version of zero
+	// to simulate a wallet that just adopted the scheme.
+	cipherSeed, err := New(0, nil, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// Now that the seed has been created, we'll attempt to convert it to a
+	// valid mnemonic.
+	mnemonic, err := cipherSeed.ToMnemonic(pass)
+	if err != nil {
+		t.Fatalf("unable to create mnemonic: %v", err)
+	}
+
+	// Next, we'll try to decrypt the mnemonic with the passphrase that we
+	// used.
+	cipherSeed2, err := mnemonic.ToCipherSeed(pass)
+	if err != nil {
+		t.Fatalf("unable to decrypt mnemonic: %v", err)
+	}
+
+	// Finally, we'll ensure that the uncovered cipher seed matches
+	// precisely.
+	assertCipherSeedEqual(t, cipherSeed, cipherSeed2)
+}
+
+// TestInvalidPassphraseRejection tests if a caller attempts to use the
+// incorrect passprhase for an enciphered seed, then the proper error is
+// returned.
+func TestInvalidPassphraseRejection(t *testing.T) {
+	t.Parallel()
+
+	// First, we'll generate a new cipher seed with a test passphrase.
+	pass := []byte("test")
+	cipherSeed, err := New(0, &testEntropy, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// Now that we have our cipher seed, we'll encipher it and request a
+	// mnemonic that we can use to recover later.
+	mnemonic, err := cipherSeed.ToMnemonic(pass)
+	if err != nil {
+		t.Fatalf("unable to create mnemonic: %v", err)
+	}
+
+	// If we try to decipher with the wrong passphrase, we should get the
+	// proper error.
+	wrongPass := []byte("kek")
+	if _, err := mnemonic.ToCipherSeed(wrongPass); err != ErrInvalidPass {
+		t.Fatalf("expected ErrInvalidPass, instead got %v", err)
+	}
+}
+
+// TestRawEncipherDecipher tests that callers are able to use the raw methods
+// to map between ciphertext and the raw plaintext deciphered seed.
+func TestRawEncipherDecipher(t *testing.T) {
+	t.Parallel()
+
+	// First, we'll generate a new cipher seed with a test passphrase.
+	pass := []byte("test")
+	cipherSeed, err := New(0, &testEntropy, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// With the cipherseed obtained, we'll now use the raw encipher method
+	// to obtain our final cipher text.
+	cipherText, err := cipherSeed.Encipher(pass)
+	if err != nil {
+		t.Fatalf("unable to encipher seed: %v", err)
+	}
+
+	mnemonic, err := cipherTextToMnemonic(cipherText)
+	if err != nil {
+		t.Fatalf("unable to create mnemonic: %v", err)
+	}
+
+	// Now that we have the ciphertext (mapped to the mnemonic), we'll
+	// attempt to decipher it raw using the user's passphrase.
+	plainSeedBytes, err := mnemonic.Decipher(pass)
+	if err != nil {
+		t.Fatalf("unable to decipher: %v", err)
+	}
+
+	// If we deserialize the plaintext seed bytes, it should exactly match
+	// the original cipher seed.
+	var newSeed CipherSeed
+	err = newSeed.decode(bytes.NewReader(plainSeedBytes[:]))
+	if err != nil {
+		t.Fatalf("unable to decode cipher seed: %v", err)
+	}
+
+	assertCipherSeedEqual(t, cipherSeed, &newSeed)
+}
+
+// TestInvalidExternalVersion tests that if we present a ciphertext with the
+// incorrect version to decipherCipherSeed, then it fails with the expected
+// error.
+func TestInvalidExternalVersion(t *testing.T) {
+	t.Parallel()
+
+	// First, we'll generate a new cipher seed.
+	cipherSeed, err := New(0, &testEntropy, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// With the cipherseed obtained, we'll now use the raw encipher method
+	// to obtain our final cipher text.
+	pass := []byte("newpasswhodis")
+	cipherText, err := cipherSeed.Encipher(pass)
+	if err != nil {
+		t.Fatalf("unable to encipher seed: %v", err)
+	}
+
+	// Now that we have the cipher text, we'll modify the first byte to be
+	// an invalid version.
+	cipherText[0] = 44
+
+	// With the version swapped, if we try to decipher it, (no matter the
+	// passphrase), it should fail.
+	_, err = decipherCipherSeed(cipherText, []byte("kek"))
+	if err != ErrIncorrectVersion {
+		t.Fatalf("wrong error: expected ErrIncorrectVersion, "+
+			"got %v", err)
+	}
+}
+
+// TestChangePassphrase tests that we're able to generate a cipher seed, then
+// change the password. If we attempt to decipher the new enciphered seed, then
+// we should get the exact same seed back.
+func TestChangePassphrase(t *testing.T) {
+	t.Parallel()
+
+	// First, we'll generate a new cipher seed with a test passphrase.
+	pass := []byte("test")
+	cipherSeed, err := New(0, &testEntropy, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// Now that we have our cipher seed, we'll encipher it and request a
+	// mnemonic that we can use to recover later.
+	mnemonic, err := cipherSeed.ToMnemonic(pass)
+	if err != nil {
+		t.Fatalf("unable to create mnemonic: %v", err)
+	}
+
+	// Now that have the mnemonic, we'll attempt to re-encipher the
+	// passphrase in order to get a brand new mnemonic.
+	newPass := []byte("strongerpassyeh!")
+	newmnemonic, err := mnemonic.ChangePass(pass, newPass)
+	if err != nil {
+		t.Fatalf("unable to change passphrase: %v", err)
+	}
+
+	// We'll now attempt to decipher the new mnemonic using the new
+	// passphrase to arrive at (what should be) the original cipher seed.
+	newCipherSeed, err := newmnemonic.ToCipherSeed(newPass)
+	if err != nil {
+		t.Fatalf("unable to decipher cipher seed: %v", err)
+	}
+
+	// Now that we have the cipher seed, we'll verify that the plaintext
+	// seed matches *identically*.
+	assertCipherSeedEqual(t, cipherSeed, newCipherSeed)
+}
+
+// TestChangePassphraseWrongPass tests that if we have a valid enciphered
+// cipherseed, but then try to change the password with the *wrong* password,
+// then we get an error.
+func TestChangePassphraseWrongPass(t *testing.T) {
+	t.Parallel()
+
+	// First, we'll generate a new cipher seed with a test passphrase.
+	pass := []byte("test")
+	cipherSeed, err := New(0, &testEntropy, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// Now that we have our cipher seed, we'll encipher it and request a
+	// mnemonic that we can use to recover later.
+	mnemonic, err := cipherSeed.ToMnemonic(pass)
+	if err != nil {
+		t.Fatalf("unable to create mnemonic: %v", err)
+	}
+
+	// Now that have the mnemonic, we'll attempt to re-encipher the
+	// passphrase in order to get a brand new mnemonic. However, we'll be
+	// using the *wrong* passphrase. This should result in an
+	// ErrInvalidPass error.
+	wrongPass := []byte("kek")
+	newPass := []byte("strongerpassyeh!")
+	_, err = mnemonic.ChangePass(wrongPass, newPass)
+	if err != ErrInvalidPass {
+		t.Fatalf("expected ErrInvalidPass, instead got %v", err)
+	}
+}
+
+// TestMnemonicEncoding uses quickcheck like property based testing to ensure
+// that we're always able to fully recover the original byte stream encoded
+// into the mnemonic phrase.
+func TestMnemonicEncoding(t *testing.T) {
+	t.Parallel()
+
+	// mainScenario is the main driver of our property based test. We'll
+	// ensure that given a random byte string of length 33 bytes, if we
+	// convert that to the mnemonic, then we should be able to reverse the
+	// conversion.
+	mainScenario := func(cipherSeedBytes [EncipheredCipherSeedSize]byte) bool {
+		mnemonic, err := cipherTextToMnemonic(cipherSeedBytes)
+		if err != nil {
+			t.Fatalf("unable to map cipher text: %v", err)
+			return false
+		}
+
+		newCipher := mnemonicToCipherText(&mnemonic)
+
+		if newCipher != cipherSeedBytes {
+			t.Fatalf("cipherseed doesn't match: expected %v, got %v",
+				cipherSeedBytes, newCipher)
+			return false
+		}
+
+		return true
+	}
+
+	if err := quick.Check(mainScenario, nil); err != nil {
+		t.Fatalf("fuzz check failed: %v", err)
+	}
+}
+
+// TestEncipherDecipher is a property-based test that ensures that given a
+// version, entropy, and birthday, then we're able to map that to a cipherseed
+// mnemonic, then back to the original plaintext cipher seed.
+func TestEncipherDecipher(t *testing.T) {
+	t.Parallel()
+
+	// mainScenario is the main driver of our property based test. We'll
+	// ensure that given a random seed tuple (internal version, entropy,
+	// and birthday) we're able to convert that to a valid cipher seed.
+	// Additionally, we should be able to decipher the final mnemonic, and
+	// recover the original cipherseed.
+	mainScenario := func(version uint8, entropy [EntropySize]byte,
+		nowInt int64, pass [20]byte) bool {
+
+		now := time.Unix(nowInt, 0)
+
+		cipherSeed, err := New(version, &entropy, now)
+		if err != nil {
+			t.Fatalf("unable to map cipher text: %v", err)
+			return false
+		}
+
+		mnemonic, err := cipherSeed.ToMnemonic(pass[:])
+		if err != nil {
+			t.Fatalf("unable to generate mnemonic: %v", err)
+			return false
+		}
+
+		cipherSeed2, err := mnemonic.ToCipherSeed(pass[:])
+		if err != nil {
+			t.Fatalf("unable to decrypt cipher seed: %v", err)
+			return false
+		}
+
+		if cipherSeed.InternalVersion != cipherSeed2.InternalVersion {
+			t.Fatalf("mismatched versions: expected %v, got %v",
+				cipherSeed.InternalVersion, cipherSeed2.InternalVersion)
+			return false
+		}
+		if cipherSeed.Birthday != cipherSeed2.Birthday {
+			t.Fatalf("mismatched birthday: expected %v, got %v",
+				cipherSeed.Birthday, cipherSeed2.Birthday)
+			return false
+		}
+		if cipherSeed.Entropy != cipherSeed2.Entropy {
+			t.Fatalf("mismatched versions: expected %x, got %x",
+				cipherSeed.Entropy[:], cipherSeed2.Entropy[:])
+			return false
+		}
+
+		return true
+	}
+
+	if err := quick.Check(mainScenario, nil); err != nil {
+		t.Fatalf("fuzz check failed: %v", err)
+	}
+}
+
+// TestSeedEncodeDecode tests that we're able to reverse the encoding of an
+// arbitrary raw seed.
+func TestSeedEncodeDecode(t *testing.T) {
+	// mainScenario is the primary driver of our property-based test. We'll
+	// ensure that given a random cipher seed, we can encode it an decode
+	// it precisely.
+	mainScenario := func(version uint8, nowInt int64,
+		entropy [EntropySize]byte) bool {
+
+		now := time.Unix(nowInt, 0)
+		seed := CipherSeed{
+			InternalVersion: version,
+			Birthday:        uint16(now.Sub(bitcoinGenesisDate) / (time.Hour * 24)),
+			Entropy:         entropy,
+		}
+
+		var b bytes.Buffer
+		if err := seed.encode(&b); err != nil {
+			t.Fatalf("unable to encode: %v", err)
+			return false
+		}
+
+		var newSeed CipherSeed
+		if err := newSeed.decode(&b); err != nil {
+			t.Fatalf("unable to decode: %v", err)
+			return false
+		}
+
+		if seed.InternalVersion != newSeed.InternalVersion {
+			t.Fatalf("mismatched versions: expected %v, got %v",
+				seed.InternalVersion, newSeed.InternalVersion)
+			return false
+		}
+		if seed.Birthday != newSeed.Birthday {
+			t.Fatalf("mismatched birthday: expected %v, got %v",
+				seed.Birthday, newSeed.Birthday)
+			return false
+		}
+		if seed.Entropy != newSeed.Entropy {
+			t.Fatalf("mismatched versions: expected %x, got %x",
+				seed.Entropy[:], newSeed.Entropy[:])
+			return false
+		}
+
+		return true
+	}
+
+	if err := quick.Check(mainScenario, nil); err != nil {
+		t.Fatalf("fuzz check failed: %v", err)
+	}
+}
+
+// TestDecipherUnknownMnenomicWord tests that if we obtain a mnemonic, the
+// modify one of the words to not be within the word list, then it's detected
+// when we attempt to map it back to the original cipher seed.
+func TestDecipherUnknownMnenomicWord(t *testing.T) {
+	t.Parallel()
+
+	// First, we'll create a new cipher seed with "test" ass a password.
+	pass := []byte("test")
+	cipherSeed, err := New(0, &testEntropy, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// Now that we have our cipher seed, we'll encipher it and request a
+	// mnemonic that we can use to recover later.
+	mnemonic, err := cipherSeed.ToMnemonic(pass)
+	if err != nil {
+		t.Fatalf("unable to create mnemonic: %v", err)
+	}
+
+	// Before we attempt to decrypt the cipher seed, we'll mutate one of
+	// the word so it isn't actually in our final word list.
+	randIndex := rand.Int31n(int32(len(mnemonic)))
+	mnemonic[randIndex] = "kek"
+
+	// If we attempt to map back to the original cipher seed now, then we
+	// should get ErrUnknownMnenomicWord.
+	_, err = mnemonic.ToCipherSeed(pass)
+	if err == nil {
+		t.Fatalf("expected ErrUnknownMnenomicWord error")
+	}
+
+	wordErr, ok := err.(ErrUnknownMnenomicWord)
+	if !ok {
+		t.Fatalf("expected ErrUnknownMnenomicWord instead got %T", err)
+	}
+
+	if wordErr.word != "kek" {
+		t.Fatalf("word mismatch: expected %v, got %v", "kek", wordErr.word)
+	}
+}
+
+// TestDecipherIncorrectMnemonic tests that if we obtain a cipherseed, but then
+// swap out words, then checksum fails.
+func TestDecipherIncorrectMnemonic(t *testing.T) {
+	// First, we'll create a new cipher seed with "test" ass a password.
+	pass := []byte("test")
+	cipherSeed, err := New(0, &testEntropy, time.Now())
+	if err != nil {
+		t.Fatalf("unable to create seed: %v", err)
+	}
+
+	// Now that we have our cipher seed, we'll encipher it and request a
+	// mnemonic that we can use to recover later.
+	mnemonic, err := cipherSeed.ToMnemonic(pass)
+	if err != nil {
+		t.Fatalf("unable to create mnemonic: %v", err)
+	}
+
+	// We'll now swap out two words from the mnemonic, which should trigger
+	// a checksum failure.
+	swapIndex1 := 9
+	swapIndex2 := 13
+	mnemonic[swapIndex1], mnemonic[swapIndex2] = mnemonic[swapIndex2], mnemonic[swapIndex1]
+
+	// If we attempt to decrypt now, we should get a checksum failure.
+	// If we attempt to map back to the original cipher seed now, then we
+	// should get ErrUnknownMnenomicWord.
+	_, err = mnemonic.ToCipherSeed(pass)
+	if err != ErrIncorrectMnemonic {
+		t.Fatalf("expected ErrIncorrectMnemonic error")
+	}
+
+}
+
+// TODO(roasbeef): add test failure checksum fail is modified, new error
+
+func init() {
+	// For the purposes of our test, we'll crank down the scrypt params a
+	// bit.
+	scryptN = 16
+	scryptR = 8
+	scryptP = 1
+}