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authorIngela Anderton Andin <ingela@erlang.org>2015-04-17 12:31:02 +0200
committerIngela Anderton Andin <ingela@erlang.org>2015-04-20 08:43:15 +0200
commitc783dce20bbb14e5b5c4797e35ea5090737bb146 (patch)
tree703e6561760e8bc7c5c1d9dc7621e6a3a9f2900e /lib/public_key/src/public_key.erl
parent3bf1096068c3a123a23e6a1499152976a2da131e (diff)
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public_key: Reject bad signatures as early as possible
Erlang bitstring type only uses as many bits as required, and does not use padding to create complete bytes as ASN1 compact_bitstring did. crypto:verify/5 will now fail, for some incorrect signatures as it expects complete bytes which an incorrect signature may not have. Instead of catching the failing crypto function and then returning false we check the input and reject it right away.
Diffstat (limited to 'lib/public_key/src/public_key.erl')
-rw-r--r--lib/public_key/src/public_key.erl39
1 files changed, 23 insertions, 16 deletions
diff --git a/lib/public_key/src/public_key.erl b/lib/public_key/src/public_key.erl
index 7ecb624311..261054637d 100644
--- a/lib/public_key/src/public_key.erl
+++ b/lib/public_key/src/public_key.erl
@@ -458,22 +458,12 @@ sign(Digest, none, #'DSAPrivateKey'{} = Key) ->
| dsa_public_key() | ec_public_key()) -> boolean().
%% Description: Verifies a digital signature.
%%--------------------------------------------------------------------
-verify(DigestOrPlainText, DigestType, Signature,
- #'RSAPublicKey'{modulus = Mod, publicExponent = Exp}) ->
- crypto:verify(rsa, DigestType, DigestOrPlainText, Signature,
- [Exp, Mod]);
-
-verify(DigestOrPlaintext, DigestType, Signature, {#'ECPoint'{point = Point}, Param}) ->
- ECCurve = ec_curve_spec(Param),
- crypto:verify(ecdsa, DigestType, DigestOrPlaintext, Signature, [Point, ECCurve]);
-
-%% Backwards compatibility
-verify(Digest, none, Signature, {_, #'Dss-Parms'{}} = Key ) ->
- verify({digest,Digest}, sha, Signature, Key);
-
-verify(DigestOrPlainText, sha = DigestType, Signature, {Key, #'Dss-Parms'{p = P, q = Q, g = G}})
- when is_integer(Key), is_binary(Signature) ->
- crypto:verify(dss, DigestType, DigestOrPlainText, Signature, [P, Q, G, Key]).
+verify(DigestOrPlainText, DigestType, Signature, Key) when is_binary(Signature) ->
+ do_verify(DigestOrPlainText, DigestType, Signature, Key);
+verify(_,_,_,_) ->
+ %% If Signature is a bitstring and not a binary we know already at this
+ %% point that the signature is invalid.
+ false.
%%--------------------------------------------------------------------
-spec pkix_dist_point(der_encoded() | #'OTPCertificate'{}) ->
@@ -753,6 +743,23 @@ ssh_encode(Entries, Type) when is_list(Entries),
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
+do_verify(DigestOrPlainText, DigestType, Signature,
+ #'RSAPublicKey'{modulus = Mod, publicExponent = Exp}) ->
+ crypto:verify(rsa, DigestType, DigestOrPlainText, Signature,
+ [Exp, Mod]);
+
+do_verify(DigestOrPlaintext, DigestType, Signature, {#'ECPoint'{point = Point}, Param}) ->
+ ECCurve = ec_curve_spec(Param),
+ crypto:verify(ecdsa, DigestType, DigestOrPlaintext, Signature, [Point, ECCurve]);
+
+%% Backwards compatibility
+do_verify(Digest, none, Signature, {_, #'Dss-Parms'{}} = Key ) ->
+ verify({digest,Digest}, sha, Signature, Key);
+
+do_verify(DigestOrPlainText, sha = DigestType, Signature, {Key, #'Dss-Parms'{p = P, q = Q, g = G}})
+ when is_integer(Key), is_binary(Signature) ->
+ crypto:verify(dss, DigestType, DigestOrPlainText, Signature, [P, Q, G, Key]).
+
do_pem_entry_encode(Asn1Type, Entity, CipherInfo, Password) ->
Der = der_encode(Asn1Type, Entity),
DecryptDer = pubkey_pem:cipher(Der, CipherInfo, Password),