Add PKCS1_v_1_5 module

2 files changed, 156 insertions, 0 deletions

diff --git a/lib/Crypto/Signature/PKCS1_v1_5.py b/lib/Crypto/Signature/PKCS1_v1_5.py
new file mode 100644
index 0000000..ae1df05
--- /dev/null
+++ b/lib/Crypto/Signature/PKCS1_v1_5.py
@@ -0,0 +1,127 @@
+# -*- coding: utf-8 -*-
+#
+#  Signature/PKCS1-v1_5.py : PKCS#1 v1.5
+#
+# ===================================================================
+# The contents of this file are dedicated to the public domain.  To
+# the extent that dedication to the public domain is not available,
+# everyone is granted a worldwide, perpetual, royalty-free,
+# non-exclusive license to exercise all rights associated with the
+# contents of this file for any purpose whatsoever.
+# No rights are reserved.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+# ===================================================================
+
+"""RSA digital signature protocol according to PKCS#1 v1.5
+
+See RFC3447 or the original RSA Labs _specification: http://www.rsa.com/rsalabs/node.asp?id=2125
+"""
+
+__revision__ = "$Id$"
+
+__all__ = [ 'sign', 'verify' ]
+
+def sign(mhash, key):
+    """Produce the PKCS#1 signature of a message.
+
+    Typical usage is the following:
+
+    .. python::
+        import Crypto.Signature.PKCS1_v1_5 as PKCS
+        import Crypto.Hash.SHA1 as SHA1
+        import Crypto.PublicKey.RSA as RSA
+
+        message = 'To be signed'
+        key = RSA.importKey('key.der')
+        h = SHA1()
+        h.update(message)
+        signature = PKCS.sign(h, key)
+
+    :Parameters:
+     mhash : hash object
+            The hash that was carried out over the message. This is an object
+            belonging to the `Crypto.Hash` module.
+     key : RSA key object
+            The key to use to sign the message. This is a `Crypto.PublicKey.RSA`
+            object and must have its private half.
+
+    :Return: A string encoding the signature.
+    :Raise ValueError:
+        If the key length is not sufficiently long to deal with the given
+        hash algorithm.
+    """
+    # TODO: Verify the key is RSA
+    blockLen = ceil_shift(key.size(),3)
+    em = EMSA_PKCS1_V1_5_ENCODE(m, blockLen)
+    sig = key.sign(em)
+    return sig
+
+def verify(mhash, key, signature):
+    """Verify that a PKCS#1 signature is authentic.
+
+    This function verifies if the party holding the private half of the key
+    really signed the message with the given hash.
+
+    Typical usage is the following:
+
+    .. python::
+        import Crypto.Signature.PKCS1_v1_5 as PKCS
+        import Crypto.Hash.SHA1 as SHA1
+        import Crypto.PublicKey.RSA as RSA
+
+        key = RSA.importKey('key.der')
+        h = SHA1()
+        h.update(message)
+        if PKCS.verify(h, key, signature):
+            print "The signature is authentic."
+        else:
+            print "The signature is not authentic."
+
+    :Parameters:
+     mhash : hash object
+            The hash that was carried out over the message. This is an object
+            belonging to the `Crypto.Hash` module.
+     key : RSA key object
+            The key to use to verify the message. This is a `Crypto.PublicKey.RSA`
+            object.
+     signature : string
+            The signature that needs to be validated.
+
+    :Return: True if verification is correct. False otherwise.
+    """
+    # TODO: Verify the key is RSA
+    blockLen = ceil_shift(self.size(),3)
+    try:
+        em = EMSA_PKCS1_V1_5_ENCODE(m, blockLen)
+    except ValueError:
+        return 0
+    return key.verify(em)
+
+def EMSA_PKCS1_V1_5_ENCODE(hash, emLen):
+    """
+    Implement the EMSA-PKCS1-V1_5-ENCODE function, as defined
+    in PKCS#1 v2.1 (RFC3447, 9.2).
+
+    :Parameters:
+     hash : hash object
+            The hash object that holds the digest of the message being signed.
+     emLen : int
+            The length in byte the final encoding must have.
+    """
+
+    digest = hash.digest()
+    digestAlgo = DerSequence([hash.oid, DerNull().encode()])
+    digestInfo = DerSequence([digestAlgo.encode(), DerOctetString(digest).encode()]).encode()
+    if emLen<len(digestInfo)+11:
+            raise ValueError("Selected hash algorith has a too long digest (%d bytes)." % len(digest))
+    PS = "\xFF" * (emLen - len(digestInfo) - 3)
+    return "\x00" + "\x01" + PS + "\x00" + digestInfo
+
diff --git a/lib/Crypto/Signature/__init__.py b/lib/Crypto/Signature/__init__.py
new file mode 100644
index 0000000..ba3cb65
--- /dev/null
+++ b/lib/Crypto/Signature/__init__.py
@@ -0,0 +1,29 @@
+# -*- coding: utf-8 -*-
+#
+# ===================================================================
+# The contents of this file are dedicated to the public domain.  To
+# the extent that dedication to the public domain is not available,
+# everyone is granted a worldwide, perpetual, royalty-free,
+# non-exclusive license to exercise all rights associated with the
+# contents of this file for any purpose whatsoever.
+# No rights are reserved.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+# ===================================================================
+
+"""Digital signature protocols
+
+A collection of standardized protocols to carry out digital signature.
+"""
+
+__all__ = [ 'PKCS1_v1_5', 'PKCS1-PSS' ]
+__revision__ = "$Id$"
+
+