diff --git a/src/test/crypto_tests.cpp b/src/test/crypto_tests.cpp
--- a/src/test/crypto_tests.cpp
+++ b/src/test/crypto_tests.cpp
@@ -403,6 +403,25 @@
         "647320746f20626520686173686564206265666f7265206265696e6720757365"
         "642062792074686520484d414320616c676f726974686d2e",
         "9b09ffa71b942fcb27635fbcd5b0e944bfdc63644f0713938a7f51535c3a35e2");
+    // Test case with key length 63 bytes.
+    TestHMACSHA256(
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a6566",
+        "7768617420646f2079612077616e7420666f72206e6f7468696e673f",
+        "9de4b546756c83516720a4ad7fe7bdbeac4298c6fdd82b15f895a6d10b0769a6");
+    // Test case with key length 64 bytes.
+    TestHMACSHA256(
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665",
+        "7768617420646f2079612077616e7420666f72206e6f7468696e673f",
+        "528c609a4c9254c274585334946b7c2661bad8f1fc406b20f6892478d19163dd");
+    // Test case with key length 65 bytes.
+    TestHMACSHA256(
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a",
+        "7768617420646f2079612077616e7420666f72206e6f7468696e673f",
+        "d06af337f359a2330deffb8e3cbe4b5b7aa8ca1f208528cdbd245d5dc63c4483");
 }
 
 BOOST_AUTO_TEST_CASE(hmac_sha512_testvectors) {
@@ -450,6 +469,34 @@
         "642062792074686520484d414320616c676f726974686d2e",
         "e37b6a775dc87dbaa4dfa9f96e5e3ffddebd71f8867289865df5a32d20cdc944"
         "b6022cac3c4982b10d5eeb55c3e4de15134676fb6de0446065c97440fa8c6a58");
+    // Test case with key length 127 bytes.
+    TestHMACSHA512(
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a6566",
+        "7768617420646f2079612077616e7420666f72206e6f7468696e673f",
+        "267424dfb8eeb999f3e5ec39a4fe9fd14c923e6187e0897063e5c9e02b2e624a"
+        "c04413e762977df71a9fb5d562b37f89dfdfb930fce2ed1fa783bbc2a203d80e");
+    // Test case with key length 128 bytes.
+    TestHMACSHA512(
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665",
+        "7768617420646f2079612077616e7420666f72206e6f7468696e673f",
+        "43aaac07bb1dd97c82c04df921f83b16a68d76815cd1a30d3455ad43a3d80484"
+        "2bb35462be42cc2e4b5902de4d204c1c66d93b47d1383e3e13a3788687d61258");
+    // Test case with key length 129 bytes.
+    TestHMACSHA512(
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a6566654a6566654a6566654a6566654a6566654a6566654a6566654a656665"
+        "4a",
+        "7768617420646f2079612077616e7420666f72206e6f7468696e673f",
+        "0b273325191cfc1b4b71d5075c8fcad67696309d292b1dad2cd23983a35feb8e"
+        "fb29795e79f2ef27f68cb1e16d76178c307a67beaad9456fac5fdffeadb16e2c");
 }
 
 BOOST_AUTO_TEST_CASE(aes_testvectors) {