2 files changed, 22 insertions, 1 deletions
diff --git a/cryptography/hazmat/backends/openssl/backend.py b/cryptography/hazmat/backends/openssl/backend.py
index bbcfa327..021ce8c4 100644
--- a/cryptography/hazmat/backends/openssl/backend.py
+++ b/cryptography/hazmat/backends/openssl/backend.py
@@ -35,7 +35,7 @@ from cryptography.hazmat.primitives.asymmetric.padding import (
     MGF1, PKCS1v15, PSS
 )
 from cryptography.hazmat.primitives.ciphers.algorithms import (
-    AES, ARC4, Blowfish, CAST5, Camellia, IDEA, TripleDES
+    AES, ARC4, Blowfish, CAST5, Camellia, IDEA, SEED, TripleDES
 )
 from cryptography.hazmat.primitives.ciphers.modes import (
     CBC, CFB, CTR, ECB, GCM, OFB
@@ -167,6 +167,12 @@ class Backend(object):
                 mode_cls,
                 GetCipherByName("bf-{mode.name}")
             )
+        for mode_cls in [CBC, CFB, OFB, ECB]:
+            self.register_cipher_adapter(
+                SEED,
+                mode_cls,
+                GetCipherByName("seed-{mode.name}")
+            )
         for cipher_cls, mode_cls in itertools.product(
             [CAST5, IDEA],
             [CBC, OFB, CFB, ECB],
diff --git a/cryptography/hazmat/primitives/ciphers/algorithms.py b/cryptography/hazmat/primitives/ciphers/algorithms.py
index 2d37e0cf..52daf178 100644
--- a/cryptography/hazmat/primitives/ciphers/algorithms.py
+++ b/cryptography/hazmat/primitives/ciphers/algorithms.py
@@ -130,3 +130,18 @@ class IDEA(object):
     @property
     def key_size(self):
         return len(self.key) * 8
+
+
+@utils.register_interface(interfaces.BlockCipherAlgorithm)
+@utils.register_interface(interfaces.CipherAlgorithm)
+class SEED(object):
+    name = "SEED"
+    block_size = 128
+    key_sizes = frozenset([128])
+
+    def __init__(self, key):
+        self.key = _verify_key_size(self, key)
+
+    @property
+    def key_size(self):
+        return len(self.key) * 8