From 9fb6e328a01839fc3e133cde3ff369589e60dca9 Mon Sep 17 00:00:00 2001
From: Pavol Rusnak <stick@gk2.sk>
Date: Tue, 8 Nov 2016 16:59:08 +0100
Subject: [PATCH] trezor.crypto: add der module

---
 src/trezor/crypto/der.py        | 21 +++++++++++++
 tests/test_trezor.crypto.der.py | 53 +++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+)
 create mode 100644 src/trezor/crypto/der.py
 create mode 100644 tests/test_trezor.crypto.der.py

diff --git a/src/trezor/crypto/der.py b/src/trezor/crypto/der.py
new file mode 100644
index 0000000000..b5eef5246d
--- /dev/null
+++ b/src/trezor/crypto/der.py
@@ -0,0 +1,21 @@
+def convert_length(l: int):
+    if l < 0x80:
+       return bytes([l])
+    elif l <= 0xFF:
+       return bytes([0x81, l])
+    elif l <= 0xFFFF:
+       return bytes([0x82, l & 0xFF, l >> 8])
+    else:
+       raise ValueError
+
+def convert_int(i: bytes):
+    i = i.lstrip(b'\x00')
+    if i[0] >= 0x80:
+        i = b'\x00' + i
+    return b'\x02' + convert_length(len(i)) + i
+
+def convert_seq(seq: tuple):
+    res = b''
+    for i in seq:
+        res += convert_int(i)
+    return b'\x30' + convert_length(len(res)) + res
diff --git a/tests/test_trezor.crypto.der.py b/tests/test_trezor.crypto.der.py
new file mode 100644
index 0000000000..6bf9d1088e
--- /dev/null
+++ b/tests/test_trezor.crypto.der.py
@@ -0,0 +1,53 @@
+from common import *
+
+from trezor.crypto import der
+
+class TestCryptoDer(unittest.TestCase):
+
+    vectors_sig = [
+        ("9a0b7be0d4ed3146ee262b42202841834698bb3ee39c24e7437df208b8b70771",
+        "2b79ab1e7736219387dffe8d615bbdba87e11477104b867ef47afed1a5ede781",
+        "30450221009a0b7be0d4ed3146ee262b42202841834698bb3ee39c24e7437df208b8b7077102202b79ab1e7736219387dffe8d615bbdba87e11477104b867ef47afed1a5ede781"),
+
+        ("6666666666666666666666666666666666666666666666666666666666666666",
+        "7777777777777777777777777777777777777777777777777777777777777777",
+        "30440220666666666666666666666666666666666666666666666666666666666666666602207777777777777777777777777777777777777777777777777777777777777777"),
+
+        ("6666666666666666666666666666666666666666666666666666666666666666",
+        "eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",
+        "304502206666666666666666666666666666666666666666666666666666666666666666022100eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee"),
+
+        ("eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",
+        "7777777777777777777777777777777777777777777777777777777777777777",
+        "3045022100eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee02207777777777777777777777777777777777777777777777777777777777777777"),
+
+        ("eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee",
+        "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
+        "3046022100eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee022100ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"),
+
+        ("0000000000000000000000000000000000000000000000000000000000000066",
+        "0000000000000000000000000000000000000000000000000000000000000077",
+        "3006020166020177"),
+
+        ("0000000000000000000000000000000000000000000000000000000000000066",
+        "00000000000000000000000000000000000000000000000000000000000000ee",
+        "3007020166020200ee"),
+
+        ("00000000000000000000000000000000000000000000000000000000000000ee",
+        "0000000000000000000000000000000000000000000000000000000000000077",
+        "3007020200ee020177"),
+
+        ("00000000000000000000000000000000000000000000000000000000000000ee",
+        "00000000000000000000000000000000000000000000000000000000000000ff",
+        "3008020200ee020200ff"),
+    ]
+
+    def test_encode_sig_der(self):
+
+        for r, s, d in self.vectors_sig:
+            r, s, d = unhexlify(r), unhexlify(s), unhexlify(d)
+            d2 = der.convert_seq((r,s))
+            self.assertEqual(d, d2)
+
+if __name__ == '__main__':
+    unittest.main()