Add compatibility layer for digging around in non-public data structures.

1 files changed, 29 insertions, 0 deletions

diff --git a/src/compat.erl b/src/compat.erl
new file mode 100644
index 0000000..bc3101d
--- /dev/null
+++ b/src/compat.erl
@@ -0,0 +1,29 @@
+-module(compat).
+-export([unpack_issuer/1, unpack_signature/1]).
+-include_lib("public_key/include/public_key.hrl").
+
+unpack_issuer(Issuer) ->
+    unpack_issuer(erlang:system_info(otp_release), Issuer).
+unpack_signature(Signature) ->
+    unpack_signature(erlang:system_info(otp_release), Signature).
+
+%% @doc Dig out alg, params and key from issuer.
+unpack_issuer(17, Issuer) ->
+    #'SubjectPublicKeyInfo'{
+       algorithm = #'AlgorithmIdentifier'{algorithm = Alg, parameters = Params},
+       subjectPublicKey = {0, Key}} = Issuer,
+    {Alg, Params, Key};
+unpack_issuer(18, Issuer) ->
+    #'SubjectPublicKeyInfo'{
+       algorithm = #'AlgorithmIdentifier'{algorithm = Alg, parameters = Params},
+       subjectPublicKey = Key} = Issuer,
+    {Alg, Params, Key}.
+
+%% @doc Unpack a #'Certificate'.signature, return the signature.
+unpack_signature(17, Signature) ->
+    {_, Sig} = Signature,
+    Sig;
+unpack_signature(18, Signature) ->
+    Signature.
+
+