support SHA256 signatures

src/highlevelcrypto.py

@@ -30,11 +30,28 @@ def decryptFast(msg,cryptor):
     return cryptor.decrypt(msg)
 # Signs with hex private key
 def sign(msg,hexPrivkey):
-    return makeCryptor(hexPrivkey).sign(msg)
+    # pyelliptic is upgrading from SHA1 to SHA256 for signing. We must 
+    # upgrade PyBitmessage gracefully. 
+    # https://github.com/yann2192/pyelliptic/pull/33
+    # More discussion: https://github.com/yann2192/pyelliptic/issues/32
+    return makeCryptor(hexPrivkey).sign(msg, digest_alg=OpenSSL.EVP_ecdsa) # SHA1
+    #return makeCryptor(hexPrivkey).sign(msg, digest_alg=OpenSSL.EVP_sha256) # SHA256. We should switch to this eventually.
 # Verifies with hex public key
 def verify(msg,sig,hexPubkey):
+    # As mentioned above, we must upgrade gracefully to use SHA256. So
+    # let us check the signature using both SHA1 and SHA256 and if one
+    # of them passes then we will be satisfied. Eventually this can 
+    # be simplified and we'll only check with SHA256. 
     try:
-        return makePubCryptor(hexPubkey).verify(sig,msg)
+        sigVerifyPassed = makePubCryptor(hexPubkey).verify(sig,msg,digest_alg=OpenSSL.EVP_ecdsa) # old SHA1 algorithm.
+    except:
+        sigVerifyPassed = False
+    if sigVerifyPassed:
+        # The signature check passed using SHA1
+        return True
+    # The signature check using SHA1 failed. Let us try it with SHA256. 
+    try:
+        return makePubCryptor(hexPubkey).verify(sig,msg,digest_alg=OpenSSL.EVP_sha256)
     except:
         return False
 

src/pyelliptic/ecc.py

@@ -299,7 +299,7 @@ class ECC:
             if privkey is not None:
                 OpenSSL.BN_free(priv_key)
 
-    def sign(self, inputb):
+    def sign(self, inputb, digest_alg=OpenSSL.EVP_ecdsa):
         """
         Sign the input with ECDSA method and returns the signature
         """
@@ -338,11 +338,11 @@ class ECC:
                 raise Exception("[OpenSSL] EC_KEY_check_key FAIL ...")
 
             OpenSSL.EVP_MD_CTX_init(md_ctx)
-            OpenSSL.EVP_DigestInit(md_ctx, OpenSSL.EVP_ecdsa())
+            OpenSSL.EVP_DigestInit_ex(md_ctx, digest_alg(), None)
 
             if (OpenSSL.EVP_DigestUpdate(md_ctx, buff, size)) == 0:
                 raise Exception("[OpenSSL] EVP_DigestUpdate FAIL ...")
-            OpenSSL.EVP_DigestFinal(md_ctx, digest, dgst_len)
+            OpenSSL.EVP_DigestFinal_ex(md_ctx, digest, dgst_len)
             OpenSSL.ECDSA_sign(0, digest, dgst_len.contents, sig, siglen, key)
             if (OpenSSL.ECDSA_verify(0, digest, dgst_len.contents, sig,
                                      siglen.contents, key)) != 1:
@@ -358,7 +358,7 @@ class ECC:
             OpenSSL.EC_POINT_free(pub_key)
             OpenSSL.EVP_MD_CTX_destroy(md_ctx)
 
-    def verify(self, sig, inputb):
+    def verify(self, sig, inputb, digest_alg=OpenSSL.EVP_ecdsa):
         """
         Verify the signature with the input and the local public key.
         Returns a boolean
@@ -392,11 +392,11 @@ class ECC:
                 raise Exception("[OpenSSL] EC_KEY_check_key FAIL ...")
 
             OpenSSL.EVP_MD_CTX_init(md_ctx)
-            OpenSSL.EVP_DigestInit(md_ctx, OpenSSL.EVP_ecdsa())
+            OpenSSL.EVP_DigestInit_ex(md_ctx, digest_alg(), None)
             if (OpenSSL.EVP_DigestUpdate(md_ctx, binputb, len(inputb))) == 0:
                 raise Exception("[OpenSSL] EVP_DigestUpdate FAIL ...")
 
-            OpenSSL.EVP_DigestFinal(md_ctx, digest, dgst_len)
+            OpenSSL.EVP_DigestFinal_ex(md_ctx, digest, dgst_len)
             ret = OpenSSL.ECDSA_verify(
                 0, digest, dgst_len.contents, bsig, len(sig), key)
 

src/pyelliptic/openssl.py

@@ -231,6 +231,10 @@ class _OpenSSL:
         self.EVP_DigestInit.restype = ctypes.c_int
         self._lib.EVP_DigestInit.argtypes = [ctypes.c_void_p, ctypes.c_void_p]
 
+        self.EVP_DigestInit_ex = self._lib.EVP_DigestInit_ex
+        self.EVP_DigestInit_ex.restype = ctypes.c_int
+        self._lib.EVP_DigestInit_ex.argtypes = 3 * [ctypes.c_void_p]
+        
         self.EVP_DigestUpdate = self._lib.EVP_DigestUpdate
         self.EVP_DigestUpdate.restype = ctypes.c_int
         self.EVP_DigestUpdate.argtypes = [ctypes.c_void_p,
@@ -241,6 +245,11 @@ class _OpenSSL:
         self.EVP_DigestFinal.argtypes = [ctypes.c_void_p,
                                          ctypes.c_void_p, ctypes.c_void_p]
 
+        self.EVP_DigestFinal_ex = self._lib.EVP_DigestFinal_ex
+        self.EVP_DigestFinal_ex.restype = ctypes.c_int
+        self.EVP_DigestFinal_ex.argtypes = [ctypes.c_void_p,
+                                            ctypes.c_void_p, ctypes.c_void_p]
+        
         self.EVP_ecdsa = self._lib.EVP_ecdsa
         self._lib.EVP_ecdsa.restype = ctypes.c_void_p
         self._lib.EVP_ecdsa.argtypes = []