diff --git a/README.md b/README.md
index 1d3cce2..e4a4b71 100644
--- a/README.md
+++ b/README.md
@@ -16,13 +16,13 @@ Crystal bindings for the [libsodium API](https://libsodium.gitbook.io/doc/)
 ## Features
 
 - [Public-Key Cryptography](https://libsodium.gitbook.io/doc/public-key_cryptography)
-  - [x] [Crypto Box Easy](https://libsodium.gitbook.io/doc/public-key_cryptography/authenticated_encryption)
+  - [x] ☑ [Crypto Box Easy](https://libsodium.gitbook.io/doc/public-key_cryptography/authenticated_encryption)
   - [x] [Sealed Box](https://libsodium.gitbook.io/doc/public-key_cryptography/sealed_boxes)
   - [ ] [Combined Signatures](https://libsodium.gitbook.io/doc/public-key_cryptography/public-key_signatures)
   - [x] [Detached Signatures](https://libsodium.gitbook.io/doc/public-key_cryptography/public-key_signatures)
 - [Secret-Key Cryptography](https://libsodium.gitbook.io/doc/secret-key_cryptography)
   - Secret Box
-    - [x] [Combined mode](https://libsodium.gitbook.io/doc/secret-key_cryptography/authenticated_encryption)
+    - [x] ☑ [Combined mode](https://libsodium.gitbook.io/doc/secret-key_cryptography/authenticated_encryption)
     - [ ] [Detached mode](https://libsodium.gitbook.io/doc/secret-key_cryptography/authenticated_encryption)
   - [x] [Secret Stream](https://libsodium.gitbook.io/doc/secret-key_cryptography/secretstream)
   - [AEAD](https://libsodium.gitbook.io/doc/secret-key_cryptography/aead)
@@ -60,6 +60,7 @@ Several features in libsodium are already provided by Crystal:
 * Random (Use [Random::Secure](https://crystal-lang.org/api/latest/Random/Secure.html))
 * SHA-2 (Use [OpenSSL::Digest](https://crystal-lang.org/api/latest/OpenSSL/Digest.html))
 * HMAC SHA-2 (Use [OpenSSL::HMAC](https://crystal-lang.org/api/latest/OpenSSL/HMAC.html))
+* Hex conversion (Use [String#hexbytes](https://crystal-lang.org/api/latest/String.html#hexbytes%3ABytes-instance-method))
 
 
 ## What should I use for my application?
diff --git a/spec/sodium/crypto_box/secret_key_spec.cr b/spec/sodium/crypto_box/secret_key_spec.cr
index 0f69379..6ba4eb3 100644
--- a/spec/sodium/crypto_box/secret_key_spec.cr
+++ b/spec/sodium/crypto_box/secret_key_spec.cr
@@ -1,6 +1,39 @@
 require "../../spec_helper"
 require "../../../src/sodium/crypto_box/secret_key"
 
+combined_test_vectors = [
+  {
+    alice_sec: "77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a",
+    alice_pub: "8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a",
+    bob_sec:   "5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6fd1c2f8b27ff88e0eb",
+    bob_pub:   "de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f",
+    nonce:     "69696ee955b62b73cd62bda875fc73d68219e0036b7a0b37",
+    plaintext: "be075fc53c81f2d5cf141316ebeb0c7b5228c52a4c62cbd44b66849b64244ffce5e" \
+               "cbaaf33bd751a1ac728d45e6c61296cdc3c01233561f41db66cce314adb310e3be8" \
+               "250c46f06dceea3a7fa1348057e2f6556ad6b1318a024a838f21af1fde048977eb4" \
+               "8f59ffd4924ca1c60902e52f0a089bc76897040e082f937763848645e0705",
+    ciphertext: "f3ffc7703f9400e52a7dfb4b3d3305d98e993b9f48681273c29650ba32fc76ce483" \
+                "32ea7164d96a4476fb8c531a1186ac0dfc17c98dce87b4da7f011ec48c97271d2c2" \
+                "0f9b928fe2270d6fb863d51738b48eeee314a7cc8ab932164548e526ae902243685" \
+                "17acfeabd6bb3732bc0e9da99832b61ca01b6de56244a9e88d5f9b37973f622a43d" \
+                "14a6599b1f654cb45a74e355a5",
+  },
+]
+
+private def box_from_vec(vec)
+  alice = Sodium::CryptoBox::SecretKey.new vec[:alice_sec].hexbytes, vec[:alice_pub].hexbytes
+  bob = Sodium::CryptoBox::SecretKey.new vec[:bob_sec].hexbytes, vec[:bob_pub].hexbytes
+  nonce = Sodium::Nonce.new vec[:nonce].hexbytes
+  plaintext = vec[:plaintext].hexbytes
+  ciphertext = vec[:ciphertext].hexbytes
+
+  alice.box(bob.public_key) do |box1|
+    bob.box(alice.public_key) do |box2|
+      yield box1, box2, nonce, plaintext, ciphertext
+    end
+  end
+end
+
 private def new_key_bytes
   Sodium::CryptoBox::SecretKey.new.to_slice
 end
@@ -65,4 +98,16 @@ describe Sodium::CryptoBox::SecretKey do
 
     String.new(decrypted).should eq(data)
   end
+
+  it "PyNaCl combined test vectors" do
+    combined_test_vectors.each do |vec|
+      box_from_vec(vec) do |box1, box2, nonce, plaintext, ciphertext|
+        encrypted, _ = box1.encrypt_easy plaintext, nonce: nonce
+        encrypted.should eq ciphertext
+
+        decrypted = box2.decrypt_easy ciphertext, nonce: nonce
+        decrypted.should eq plaintext
+      end
+    end
+  end
 end
diff --git a/spec/sodium/secret_box_spec.cr b/spec/sodium/secret_box_spec.cr
index e879fb0..a43b495 100644
--- a/spec/sodium/secret_box_spec.cr
+++ b/spec/sodium/secret_box_spec.cr
@@ -1,17 +1,66 @@
 require "../spec_helper"
 require "../../src/sodium/secret_box"
 
+combined_test_vectors = [
+  {
+    key:       "1b27556473e985d462cd51197a9a46c76009549eac6474f206c4ee0844f68389",
+    nonce:     "69696ee955b62b73cd62bda875fc73d68219e0036b7a0b37",
+    plaintext: "be075fc53c81f2d5cf141316ebeb0c7b5228c52a4c62cbd44b66849b64244ffce5e" \
+               "cbaaf33bd751a1ac728d45e6c61296cdc3c01233561f41db66cce314adb310e3be8" \
+               "250c46f06dceea3a7fa1348057e2f6556ad6b1318a024a838f21af1fde048977eb4" \
+               "8f59ffd4924ca1c60902e52f0a089bc76897040e082f937763848645e0705",
+    ciphertext: "f3ffc7703f9400e52a7dfb4b3d3305d98e993b9f48681273c29650ba32fc76ce483" \
+                "32ea7164d96a4476fb8c531a1186ac0dfc17c98dce87b4da7f011ec48c97271d2c2" \
+                "0f9b928fe2270d6fb863d51738b48eeee314a7cc8ab932164548e526ae902243685" \
+                "17acfeabd6bb3732bc0e9da99832b61ca01b6de56244a9e88d5f9b37973f622a43d" \
+                "14a6599b1f654cb45a74e355a5",
+  },
+]
+
+private def box_from_test_vector(vec)
+  box = Sodium::SecretBox.new vec[:key].hexbytes
+  nonce = Sodium::Nonce.new vec[:nonce].hexbytes
+  plaintext = vec[:plaintext].hexbytes
+  ciphertext = vec[:ciphertext].hexbytes
+
+  {box, nonce, plaintext, ciphertext}
+end
+
 describe Sodium::SecretBox do
   it "encrypts/decrypts" do
-    key = Sodium::SecretBox.new
+    box = Sodium::SecretBox.new
 
     message = "foobar"
-    encrypted, nonce = key.encrypt_easy message
-    decrypted = key.decrypt_easy encrypted, nonce
+    encrypted, nonce = box.encrypt_easy message
+    decrypted = box.decrypt_easy encrypted, nonce
     message.should eq String.new(decrypted)
 
     expect_raises(Sodium::Error::DecryptionFailed) do
-      key.decrypt_easy "badmsgbadmsgbadmsgbadmsgbadmsg".to_slice, nonce
+      box.decrypt_easy "badmsgbadmsgbadmsgbadmsgbadmsg".to_slice, nonce
+    end
+  end
+
+  it "PyNaCl combined test vectors" do
+    combined_test_vectors.each do |vec|
+      box, nonce, plaintext, ciphertext = box_from_test_vector vec
+
+      encrypted = box.encrypt_easy plaintext, nonce
+      encrypted.should eq ciphertext
+
+      decrypted = box.decrypt_easy encrypted, nonce
+      plaintext.should eq decrypted
+    end
+  end
+
+  pending "detached test vectors" do
+    detached_test_vectors.each do |vec|
+      box, nonce, plaintext, ciphertext = box_from_test_vector vec
+
+      encrypted = box.encrypt_detached plaintext, nonce
+      encrypted.should eq ciphertext
+
+      decrypted = box.decrypt_detached encrypted, nonce
+      plaintext.should eq decrypted
     end
   end
 end