initial revision

3 files changed, 121 insertions, 0 deletions

diff --git a/pysnmp/proto/secmod/rfc3414/priv/__init__.py b/pysnmp/proto/secmod/rfc3414/priv/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/pysnmp/proto/secmod/rfc3414/priv/__init__.py
diff --git a/pysnmp/proto/secmod/rfc3414/priv/base.py b/pysnmp/proto/secmod/rfc3414/priv/base.py
new file mode 100644
index 00000000..8690d4de
--- /dev/null
+++ b/pysnmp/proto/secmod/rfc3414/priv/base.py
@@ -0,0 +1,4 @@
+class AbstractEncryptionService:
+    serviceID = None
+    def encryptData(self, encryptKey, dataToEncrypt): pass
+    def decryptData(self, decryptKey, privParameters, encryptedData): pass
diff --git a/pysnmp/proto/secmod/rfc3414/priv/des.py b/pysnmp/proto/secmod/rfc3414/priv/des.py
new file mode 100644
index 00000000..aead8cd2
--- /dev/null
+++ b/pysnmp/proto/secmod/rfc3414/priv/des.py
@@ -0,0 +1,117 @@
+import random, string
+from pysnmp.proto.secmod.rfc3414.priv import base
+from pyasn1.type import univ
+from pysnmp.proto import error
+
+try:
+    from Crypto.Cipher import DES
+except ImportError:
+    DES = None
+    
+random.seed()
+
+# 8.2.4
+
+class Des(base.AbstractEncryptionService):
+    serviceID = (1, 3, 6, 1, 6, 3, 10, 1, 2, 2) # usmDESPrivProtocol
+    _localInt = long(random.random()*0xffffffff)
+    # 8.1.1.1
+    def __getEncryptionKey(self, mibInstrumController, privKey):
+        desKey = privKey[:8]
+        preIV = privKey[8:16]
+
+        snmpEngineBoots, = mibInstrumController.mibBuilder.importSymbols(
+            'SNMP-FRAMEWORK-MIB', 'snmpEngineBoots'
+            )
+        securityEngineBoots = long(snmpEngineBoots.syntax)
+
+        salt = [
+            securityEngineBoots>>24&0xff,
+            securityEngineBoots>>16&0xff,
+            securityEngineBoots>>8&0xff,
+            securityEngineBoots&0xff,
+            self._localInt>>24&0xff,
+            self._localInt>>16&0xff,
+            self._localInt>>8&0xff,
+            self._localInt&0xff
+            ]
+        if self._localInt == 0xffffffff:
+            self._localInt = 0
+        else:
+            self._localInt = self._localInt + 1
+
+        return desKey, \
+               string.join(map(lambda x: chr(x), salt), ''), \
+               string.join(map(lambda x,y: chr(x^ord(y)), salt, preIV), '')
+
+    def __getDecryptionKey(self, mibInstrumController, privKey, salt):
+        return privKey[:8], string.join(
+            map(lambda x,y: chr(ord(x)^ord(y)), salt, privKey[8:16]), ''
+            )
+        
+    # 8.2.4.1
+    def encryptData(self, mibInstrumController, encryptKey, dataToEncrypt):
+        if DES is None:
+            raise error.StatusInformation(
+                errorIndication='encryptionError'
+                )
+        
+        # 8.3.1.1
+        desKey, salt, iv = self.__getEncryptionKey(
+            mibInstrumController, str(encryptKey)
+            )
+
+        # 8.3.1.2
+        privParameters = univ.OctetString(salt)
+
+        # 8.1.1.2
+        desObj = DES.new(desKey, DES.MODE_CBC, iv) # XXX
+        plaintext =  dataToEncrypt + '\x00' * (8 - len(dataToEncrypt) % 8)
+        ciphertext = desObj.encrypt(plaintext)
+
+        # 8.3.1.3 & 4
+        return univ.OctetString(ciphertext), privParameters
+        
+    # 8.2.4.2
+    def decryptData(self, mibInstrumController, decryptKey,
+                    privParameters, encryptedData):
+        if DES is None:
+            raise error.StatusInformation(
+                errorIndication='decryptionError'
+                )
+        
+        # 8.3.2.1
+        if len(privParameters) != 8:
+            raise error.StatusInformation(
+                errorIndication='decryptionError'
+                )
+            
+        # 8.3.2.2
+        salt = str(privParameters)
+
+        # 8.3.2.3
+        desKey, iv = self.__getDecryptionKey(
+            mibInstrumController, str(decryptKey), salt
+            )
+
+        # 8.3.2.4 -> 8.1.1.3
+        if len(encryptedData) % 8 != 0:
+            raise error.StatusInformation(
+                errorIndication='decryptionError'
+                )
+
+        desObj = DES.new(desKey, DES.MODE_CBC, iv)
+        
+        # 8.3.2.6
+        return desObj.decrypt(str(encryptedData))
+
+if __name__ == '__main__':
+    from pysnmp.smi import builder, instrum
+
+    mibInstrumController = instrum.MibInstrumController(
+        builder.MibBuilder()
+        )
+
+    d = Des()
+    ct, p = d.encryptData(mibInstrumController, '1234567890123456', 'security? not my problem!')
+    print d.decryptData(mibInstrumController, '1234567890123456', p, ct)