joinmarket: add pkg and local dependencies

pkgs/joinmarket/python-bitcointx/default.nix

@@ -0,0 +1,27 @@
+{ lib, buildPythonPackage, fetchurl, secp256k1, openssl }:
+
+buildPythonPackage rec {
+  pname = "python-bitcointx";
+  version = "1.1.1";
+
+  src = fetchurl {
+    url = "https://github.com/Simplexum/${pname}/archive/${pname}-v${version}.tar.gz";
+    sha256 = "35edd694473517508367338888633954eaa91b2622b3caada8fd3030ddcacba2";
+  };
+
+  patchPhase = ''
+    for path in core/secp256k1.py tests/test_load_secp256k1.py; do
+      substituteInPlace "bitcointx/$path" \
+        --replace "ctypes.util.find_library('secp256k1')" "'${secp256k1}/lib/libsecp256k1.so'"
+    done
+    substituteInPlace bitcointx/core/key.py \
+      --replace "ctypes.util.find_library('ssl')" "'${openssl.out}/lib/libssl.so'"
+  '';
+
+  meta = with lib; {
+    description = "Interface to Bitcoin transaction data structures";
+    homepage = "https://github.com/Simplexum/python-bitcointx";
+    maintainers = with maintainers; [ nixbitcoin ];
+    license = licenses.gpl3;
+  };
+}

pkgs/joinmarket/python-bitcointx/get-sha256.sh

@@ -0,0 +1,24 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash -p git gnupg
+set -euo pipefail
+
+TMPDIR="$(mktemp -d -p /tmp)"
+trap "rm -rf $TMPDIR" EXIT
+cd $TMPDIR
+
+echo "Fetching latest release"
+git clone https://github.com/simplexum/python-bitcointx 2> /dev/null
+cd python-bitcointx
+latest=$(git describe --tags `git rev-list --tags --max-count=1`)
+echo "Latest release is ${latest}"
+
+# GPG verification
+export GNUPGHOME=$TMPDIR
+echo "Fetching Dimitry Pethukov's Key"
+gpg --keyserver hkps://keyserver.ubuntu.com --recv-keys B17A35BBA187395784E2A6B32301D26BDC15160D 2> /dev/null
+echo "Verifying latest release"
+git verify-commit ${latest}
+
+echo "tag: ${latest}"
+# The prefix option is necessary because GitHub prefixes the archive contents in this format
+echo "sha256: $(git archive --format tar.gz --prefix=python-bitcointx-"${latest}"/ ${latest} | sha256sum | cut -d\  -f1)"