Add ability to import RSAPublicKey objects (encoded in DER or PEM)

2 files changed, 36 insertions, 6 deletions

diff --git a/lib/Crypto/PublicKey/RSA.py b/lib/Crypto/PublicKey/RSA.py
index db109a9..99d851d 100644
--- a/lib/Crypto/PublicKey/RSA.py
+++ b/lib/Crypto/PublicKey/RSA.py
@@ -557,6 +557,9 @@ class RSAImplementation(object):
 
             # Keep on trying PKCS#1, but now for a public key
             if len(der)==2:
+                # The DER object is an RSAPublicKey SEQUENCE with two elements
+                if der.hasOnlyInts():
+                    return self.construct(der[:])
                 # The DER object is a SubjectPublicKeyInfo SEQUENCE with two elements:
                 # an 'algorithm' (or 'algorithmIdentifier') SEQUENCE and a 'subjectPublicKey' BIT STRING.
                 # 'algorithm' takes the value given a few lines above.
@@ -590,13 +593,16 @@ class RSAImplementation(object):
         :Parameter externKey:
             The RSA key to import, encoded as a string.
 
-            The key can be in any of the following formats:
+            An RSA public key can be in any of the following formats:
 
-            - X.509 `subjectPublicKeyInfo` DER SEQUENCE (binary, public key only)
-            - X.509 `subjectPublicKeyInfo` DER SEQUENCE (PEM encoding, public key only)
-            - `PKCS#1`_ `RSAPrivateKey` DER SEQUENCE (binary, private key only)
-            - `PKCS#8`_ `PrivateKeyInfo` DER SEQUENCE (binary, private key only)
-            - PKCS#8 `PrivateKeyInfo` DER SEQUENCE (PEM encoding, private key only)
+            - X.509 `subjectPublicKeyInfo` DER SEQUENCE (binary or PEM encoding)
+            - `PKCS#1`_ `RSAPublicKey` DER SEQUENCE (binary or PEM encoding)
+            - OpenSSH (textual public key only)
+
+            An RSA private key can be in any of the following formats:
+
+            - PKCS#1 `RSAPrivateKey` DER SEQUENCE (binary or PEM encoding)
+            - `PKCS#8`_ `PrivateKeyInfo` DER SEQUENCE (binary or PEM encoding)
             - OpenSSH (textual public key only)
 
             For details about the PEM encoding, see `RFC1421`_/`RFC1423`_.
diff --git a/lib/Crypto/SelfTest/PublicKey/test_importKey.py b/lib/Crypto/SelfTest/PublicKey/test_importKey.py
index 0fd59f7..28a7eee 100644
--- a/lib/Crypto/SelfTest/PublicKey/test_importKey.py
+++ b/lib/Crypto/SelfTest/PublicKey/test_importKey.py
@@ -30,6 +30,15 @@ from Crypto.PublicKey import RSA
 from Crypto.SelfTest.st_common import *
 from Crypto.Util.py3compat import *
 from Crypto.Util.number import inverse
+from Crypto.Util import asn1
+
+def der2pem(der, text='PUBLIC'):
+    import binascii
+    chunks = [ binascii.b2a_base64(der[i:i+48]) for i in range(0, len(der), 48) ]
+    pem  = b('-----BEGIN %s KEY-----\n' % text)
+    pem += b('').join(chunks)
+    pem += b('-----END %s KEY-----' % text)
+    return pem
 
 class ImportKeyTests(unittest.TestCase):
     # 512-bit RSA key generated with openssl
@@ -246,6 +255,21 @@ Lr7UkvEtFrRhDDKMtuIIq19FrL4pUIMymPMSLBn3hJLe30Dw48GQM4UCAwEAAQ==
         self.assertEqual(key.p, self.p)
         self.assertEqual(key.q, self.q)
 
+    def testImportKey11(self):
+        """Verify import of RSAPublicKey DER SEQUENCE"""
+        der = asn1.DerSequence([17, 3]).encode()
+        key = self.rsa.importKey(der)
+        self.assertEqual(key.n, 17)
+        self.assertEqual(key.e, 3)
+
+    def testImportKey12(self):
+        """Verify import of RSAPublicKey DER SEQUENCE, encoded with PEM"""
+        der = asn1.DerSequence([17, 3]).encode()
+        pem = der2pem(der)
+        key = self.rsa.importKey(pem)
+        self.assertEqual(key.n, 17)
+        self.assertEqual(key.e, 3)
+
     ###
     def testExportKey1(self):
         key = self.rsa.construct([self.n, self.e, self.d, self.p, self.q, self.pInv])