diff --git a/src/libWiiPy/title/cert.py b/src/libWiiPy/title/cert.py
index 486e33e..63bbe1c 100644
--- a/src/libWiiPy/title/cert.py
+++ b/src/libWiiPy/title/cert.py
@@ -210,23 +210,44 @@ def verify_ca_cert(ca_cert: Certificate) -> bool:
     bool
         Whether the certificate is valid or not.
     """
-    root_key_modulus = (b'\xf8$lX\xba\xe7P\x03\x01\xfb\xb7\xc2\xeb\xe0\x01\x05q\xda\x92#x\xf0QN\xc0\x03\x1d\xd0\xd2\x1e'
-                        b'\xd3\xd0~\xfc\x85 i\xb5\xde\x9b\xb9Q\xa8\xbc\x90\xa2D\x92m7\x92\x95\xae\x946\xaa\xa6\xa3\x02Q'
-                        b'\x0c{\x1d\xed\xd5\xfb \x86\x9d\x7f0\x16\xf6\xbee\xd3\x83\xa1m\xb32\x1b\x955\x18\x90\xb1p\x02'
-                        b'\x93~\xe1\x93\xf5~\x99\xa2GN\x9d8$\xc7\xae\xe3\x85A\xf5g\xe7Q\x8cz\x0e8\xe7\xeb\xafA\x19\x1b'
-                        b'\xcf\xf1{B\xa6\xb4\xed\xe6\xce\x8d\xe71\x8f\x7fR\x04\xb3\x99\x0e"gE\xaf\xd4\x85\xb2D\x93\x00'
-                        b'\x8b\x08\xc7\xf6\xb7\xe5k\x02\xb3\xe8\xfe\x0c\x9d\x85\x9c\xb8\xb6\x82#\xb8\xab\'\xee_e8\x07'
-                        b'\x8b-\xb9\x1e*\x15>\x85\x81\x80r\xa2;m\xd92\x81\x05Oo\xb0\xf6\xf5\xad(>\xca\x0bz\xf3TU\xe0='
-                        b'\xa7\xb6\x83&\xf3\xec\x83J\xf3\x14\x04\x8a\xc6\xdf \xd2\x85\x08g<\xabb\xa2\xc7\xbc\x13\x1aS>'
-                        b'\x0bf\x80k\x1c0fK7#1\xbd\xc4\xb0\xca\xd8\xd1\x1e\xe7\xbb\xd9(UH\xaa\xec\x1ff\xe8!\xb3\xc8'
-                        b'\xa0Gi\x00\xc5\xe6\x88\xe8\x0c\xce<a\xd6\x9c\xbb\xa17\xc6`Ozr\xdd\x8c{>=Q)\r\xaajY{\x08\x1f'
-                        b'\x9d63\xa3Fz5a\t\xac\xa7\xdd}./\xb2\xc1\xae\xb8\xe2\x0fH\x92\xd8\xb9\xf8\xb4oN<\x11\xf4\xf4}'
-                        b'\x8bu}\xfe\xfe\xa3\x89\x9c3Y\\^\xfd\xeb\xcb\xab\xe8A>:\x9a\x80<i5n\xb2\xb2\xad\\\xc4\xc8XE^'
-                        b'\xf5\xf7\xb3\x06D\xb4|d\x06\x8c\xdf\x80\x9fv\x02Z-\xb4F\xe0=|\xf6/4\xe7\x02E{\x02\xa4\xcf]'
-                        b'\x9d\xd5<\xa5:|\xa6)x\x8cg\xca\x08\xbf\xec\xcaC\xa9W\xad\x16\xc9N\x1c\xd8u\xca\x10}\xce~\x01'
-                        b'\x18\xf0\xdfk\xfe\xe5\x1d\xdb\xd9\x91\xc2n`\xcdHX\xaaY,\x82\x00u\xf2\x9fRl\x91|o\xe5@>\xa7'
-                        b'\xd4\xa5\x0c\xec;s\x84\xde\x88n\x82\xd2\xebMNB\xb5\xf2\xb1I\xa8\x1e\xa7\xceqD\xdc)\x94\xcf'
-                        b'\xc4N\x1f\x91\xcb\xd4\x95')
+    if ca_cert.issuer != "Root" or ca_cert.child_name.find("CA") == -1:
+        raise ValueError("The provided certificate is not a CA certificate!")
+    if ca_cert.child_name == "CA00000001":
+        root_key_modulus = \
+            (b'\xf8$lX\xba\xe7P\x03\x01\xfb\xb7\xc2\xeb\xe0\x01\x05q\xda\x92#x\xf0QN\xc0\x03\x1d\xd0\xd2\x1e\xd3\xd0~'
+             b'\xfc\x85 i\xb5\xde\x9b\xb9Q\xa8\xbc\x90\xa2D\x92m7\x92\x95\xae\x946\xaa\xa6\xa3\x02Q\x0c{\x1d\xed\xd5'
+             b'\xfb \x86\x9d\x7f0\x16\xf6\xbee\xd3\x83\xa1m\xb32\x1b\x955\x18\x90\xb1p\x02\x93~\xe1\x93\xf5~\x99\xa2GN'
+             b'\x9d8$\xc7\xae\xe3\x85A\xf5g\xe7Q\x8cz\x0e8\xe7\xeb\xafA\x19\x1b\xcf\xf1{B\xa6\xb4\xed\xe6\xce\x8d\xe71'
+             b'\x8f\x7fR\x04\xb3\x99\x0e"gE\xaf\xd4\x85\xb2D\x93\x00\x8b\x08\xc7\xf6\xb7\xe5k\x02\xb3\xe8\xfe\x0c\x9d'
+             b'\x85\x9c\xb8\xb6\x82#\xb8\xab\'\xee_e8\x07\x8b-\xb9\x1e*\x15>\x85\x81\x80r\xa2;m\xd92\x81\x05Oo\xb0\xf6'
+             b'\xf5\xad(>\xca\x0bz\xf3TU\xe0=\xa7\xb6\x83&\xf3\xec\x83J\xf3\x14\x04\x8a\xc6\xdf \xd2\x85\x08g<\xabb\xa2'
+             b'\xc7\xbc\x13\x1aS>\x0bf\x80k\x1c0fK7#1\xbd\xc4\xb0\xca\xd8\xd1\x1e\xe7\xbb\xd9(UH\xaa\xec\x1ff\xe8!\xb3'
+             b'\xc8\xa0Gi\x00\xc5\xe6\x88\xe8\x0c\xce<a\xd6\x9c\xbb\xa17\xc6`Ozr\xdd\x8c{>=Q)\r\xaajY{\x08\x1f\x9d63'
+             b'\xa3Fz5a\t\xac\xa7\xdd}./\xb2\xc1\xae\xb8\xe2\x0fH\x92\xd8\xb9\xf8\xb4oN<\x11\xf4\xf4}\x8bu}\xfe\xfe\xa3'
+             b'\x89\x9c3Y\\^\xfd\xeb\xcb\xab\xe8A>:\x9a\x80<i5n\xb2\xb2\xad\\\xc4\xc8XE^\xf5\xf7\xb3\x06D\xb4|d\x06\x8c'
+             b'\xdf\x80\x9fv\x02Z-\xb4F\xe0=|\xf6/4\xe7\x02E{\x02\xa4\xcf]\x9d\xd5<\xa5:|\xa6)x\x8cg\xca\x08\xbf\xec'
+             b'\xcaC\xa9W\xad\x16\xc9N\x1c\xd8u\xca\x10}\xce~\x01\x18\xf0\xdfk\xfe\xe5\x1d\xdb\xd9\x91\xc2n`\xcdHX\xaa'
+             b'Y,\x82\x00u\xf2\x9fRl\x91|o\xe5@>\xa7\xd4\xa5\x0c\xec;s\x84\xde\x88n\x82\xd2\xebMNB\xb5\xf2\xb1I\xa8\x1e'
+             b'\xa7\xceqD\xdc)\x94\xcf\xc4N\x1f\x91\xcb\xd4\x95')
+    elif ca_cert.child_name == "CA00000002":
+        root_key_modulus = \
+            (b'\x00\xd0\x1f\xe1\x00\xd45V\xb2KV\xda\xe9q\xb5\xa5\xd3\x84\xb90\x03\xbe\x1b\xbf(\xa20[\x06\x06EF}[\x02Q'
+             b'\xd2V\x1a\'O\x9e\x9f\x9c\xecdaP\xab=*\xe36hf\xac\xa4\xba\xe8\x1a\xe3\xd7\x9a\xa6\xb0J\x8b\xcb\xa7\xe6'
+             b'\xfbd\x89E\xeb\xdf\xdb\x85\xba\t\x1f\xd7\xd1\x14\xb5\xa3\xa7\x80\xe3\xa2.n\xcd\x87\xb5\xa4\xc6\xf9\x10'
+             b'\xe4\x03"\x08\x81K\x0c\xee\xa1\xa1}\xf79i_a~\xf65(\xdb\x94\x967\xa0V\x03\x7f{2A8\x95\xc0\xa8\xf1\x98.'
+             b'\x15e\xe3\x8e\xed\xc2.Y\x0e\xe2g{\x86\t\xf4\x8c.0?\xbc@\\\xac\x18\x04/\x82 \x84\xe4\x93h\x03\xda\x7fA4'
+             b'\x92HV+\x8e\xe1/x\xf8\x03$c0\xbc{\xe7\xeerJ\xf4X\xa4r\xe7\xabF\xa1\xa7\xc1\x0c/\x18\xfa\x07\xc3\xdd\xd8'
+             b'\x98\x06\xa1\x1c\x9c\xc10\xb2G\xa3<\x8dG\xdeg\xf2\x9eUw\xb1\x1cCI=[\xbav4\xa7\xe4\xe7\x151\xb7\xdfY\x81'
+             b'\xfe$\xa1\x14UL\xbd\x8f\x00\\\xe1\xdb5\x08\\\xcf\xc7x\x06\xb6\xde%@h\xa2l\xb5I-E\x80C\x8f\xe1\xe5\xa9'
+             b'\xedu\xc5\xedE\x1d\xcex\x949\xcc\xc3\xba(\xa21*\x1b\x87\x19\xef\x0fs\xb7\x13\x95\x0c\x02Y\x1atb\xa6\x07'
+             b'\xf3|\n\xa7\xa1\x8f\xa9C\xa3mu*_A\x92\xf0\x13a\x00\xaa\x9c\xb4\x1b\xbe\x14\xbe\xb1\xf9\xfci/\xdf\xa0\x94'
+             b'F\xdeZ\x9d\xde,\xa5\xf6\x8c\x1c\x0c!B\x92\x87\xcb-\xaa\xa3\xd2cu/s\xe0\x9f\xafDy\xd2\x81t)\xf6\x98\x00'
+             b'\xaf\xdekY-\xc1\x98\x82\xbd\xf5\x81\xcc\xab\xf2\xcb\x91\x02\x9e\xf3\\L\xfd\xbb\xffI\xc1\xfa\x1b/\xe3\x1d'
+             b'\xe7\xa5`\xec\xb4~\xbc\xfe2B[\x95o\x81\xb6\x99\x17H~;x\x91Q\xdb.x\xb1\xfd.\xbe~bk>\xa1e\xb4\xfb\x00\xcc'
+             b'\xb7Q\xafPs)\xc4\xa3\x93\x9e\xa6\xdd\x9cP\xa0\xe78k\x01EykA\xafa\xf7\x85U\x94O;\xc2-\xc3\xbd\r\x00\xf8y'
+             b'\x8aB\xb1\xaa\xa0\x83 e\x9a\xc79Z\xb4\xf3)')
+    else:
+        raise ValueError("The provided CA certificate is not valid!")
     root_key_exponent = 0x00010001
     cert_hash = SHA1.new(ca_cert.dump()[576:])
     public_key = RSA.construct((int.from_bytes(root_key_modulus), root_key_exponent))
@@ -253,6 +274,12 @@ def verify_cert_sig(ca_cert: Certificate, target_cert: Certificate) -> bool:
     bool
         Whether the certificate's signature is valid or not.
     """
+    if ca_cert.issuer != "Root" or ca_cert.child_name.find("CA") == -1:
+        raise ValueError("The provided certificate is not a CA certificate!")
+    # The issuer of the TMD/Ticket certs is Root-CA0000000X, so prepend "Root-" to the CA cert child name. If these
+    # don't match, then there's probably a mismatch between retail and development certs.
+    if f"Root-{ca_cert.child_name}" != target_cert.issuer:
+        raise ValueError("The certificate you are trying to verify does not match the provided CA certificate!")
     cert_hash = SHA1.new(target_cert.dump()[320:])
     public_key = RSA.construct((ca_cert.pub_key_modulus, ca_cert.pub_key_exponent))
     try:
@@ -278,6 +305,10 @@ def verify_tmd_sig(tmd_cert: Certificate, tmd: TMD) -> bool:
     bool
         Whether the TMD's signature is valid or not.
     """
+    if tmd_cert.issuer.find("Root-CA") == -1 or tmd_cert.child_name.find("CP") == -1:
+        raise ValueError("The provided TMD certificate is not valid!")
+    if f"{tmd_cert.issuer}-{tmd_cert.child_name}" != tmd.signature_issuer:
+        raise ValueError("The signature you are trying to verify was not created with the provided TMD certificate!")
     tmd_hash = SHA1.new(tmd.dump()[320:])
     public_key = RSA.construct((tmd_cert.pub_key_modulus, tmd_cert.pub_key_exponent))
     try:
@@ -303,6 +334,10 @@ def verify_ticket_sig(ticket_cert: Certificate, ticket: Ticket) -> bool:
     bool
         Whether the Ticket's signature is valid or not.
     """
+    if ticket_cert.issuer.find("Root-CA") == -1 or ticket_cert.child_name.find("XS") == -1:
+        raise ValueError("The provided Ticket certificate is not valid!")
+    if f"{ticket_cert.issuer}-{ticket_cert.child_name}" != ticket.signature_issuer:
+        raise ValueError("The signature you are trying to verify was not created with the provided Ticket certificate!")
     ticket_hash = SHA1.new(ticket.dump()[320:])
     public_key = RSA.construct((ticket_cert.pub_key_modulus, ticket_cert.pub_key_exponent))
     try:
diff --git a/src/libWiiPy/title/ticket.py b/src/libWiiPy/title/ticket.py
index 8485ab3..fb85c6a 100644
--- a/src/libWiiPy/title/ticket.py
+++ b/src/libWiiPy/title/ticket.py
@@ -107,7 +107,7 @@ class Ticket:
             self.signature = ticket_data.read(256)
             # Signature issuer.
             ticket_data.seek(0x140)
-            self.signature_issuer = str(ticket_data.read(64).decode())
+            self.signature_issuer = str(ticket_data.read(64).replace(b'\x00', b'').decode())
             # ECDH data.
             ticket_data.seek(0x180)
             self.ecdh_data = ticket_data.read(60)
@@ -182,7 +182,10 @@ class Ticket:
         # Padding to 64 bytes.
         ticket_data += b'\x00' * 60
         # Signature issuer.
-        ticket_data += str.encode(self.signature_issuer)
+        signature_issuer = self.signature_issuer.encode()
+        while len(signature_issuer) < 0x40:
+            signature_issuer += b'\x00'
+        ticket_data += signature_issuer
         # ECDH data.
         ticket_data += self.ecdh_data
         # Ticket version.
diff --git a/src/libWiiPy/title/tmd.py b/src/libWiiPy/title/tmd.py
index 96958d6..bdc2e1a 100644
--- a/src/libWiiPy/title/tmd.py
+++ b/src/libWiiPy/title/tmd.py
@@ -83,7 +83,7 @@ class TMD:
             self.signature = tmd_data.read(256)
             # Signing certificate issuer.
             tmd_data.seek(0x140)
-            self.signature_issuer = str(tmd_data.read(64).decode())
+            self.signature_issuer = str(tmd_data.read(64).replace(b'\x00', b'').decode())
             # TMD version, seems to usually be 0, but I've seen references to other numbers.
             tmd_data.seek(0x180)
             self.tmd_version = int.from_bytes(tmd_data.read(1))
@@ -175,7 +175,10 @@ class TMD:
         # Padding to 64 bytes.
         tmd_data += b'\x00' * 60
         # Signing certificate issuer.
-        tmd_data += str.encode(self.signature_issuer)
+        signature_issuer = self.signature_issuer.encode()
+        while len(signature_issuer) < 0x40:
+            signature_issuer += b'\x00'
+        tmd_data += signature_issuer
         # TMD version.
         tmd_data += int.to_bytes(self.tmd_version, 1)
         # Certificate Authority CRL version.