1 files changed, 106 insertions, 0 deletions
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpConstants.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpConstants.java
new file mode 100644
index 000000000..90991ba15
--- /dev/null
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpConstants.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2015 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.sufficientlysecure.keychain.pgp;
+
+import org.spongycastle.bcpg.CompressionAlgorithmTags;
+import org.spongycastle.bcpg.HashAlgorithmTags;
+import org.spongycastle.bcpg.SymmetricKeyAlgorithmTags;
+
+import java.util.ArrayList;
+
+public class PgpConstants {
+
+    public static ArrayList<Integer> sPreferredSymmetricAlgorithms = new ArrayList<>();
+    public static ArrayList<Integer> sPreferredHashAlgorithms = new ArrayList<>();
+    public static ArrayList<Integer> sPreferredCompressionAlgorithms = new ArrayList<>();
+
+    // TODO: use hashmaps for contains in O(1) and intersections!
+
+    /*
+     * Most preferred is first
+     * These arrays are written as preferred algorithms into the keys on creation.
+     * Other implementations may choose to honor this selection.
+     *
+     * These lists also define the only algorithms which are used in OpenKeychain.
+     * We do not support algorithms such as MD5
+     */
+    static {
+        sPreferredSymmetricAlgorithms.add(SymmetricKeyAlgorithmTags.AES_256);
+        sPreferredSymmetricAlgorithms.add(SymmetricKeyAlgorithmTags.AES_192);
+        sPreferredSymmetricAlgorithms.add(SymmetricKeyAlgorithmTags.AES_128);
+        sPreferredSymmetricAlgorithms.add(SymmetricKeyAlgorithmTags.TWOFISH);
+
+        // NOTE: some implementations do not support SHA512, thus we choose SHA256 as default (Mailvelope?)
+        sPreferredHashAlgorithms.add(HashAlgorithmTags.SHA256);
+        sPreferredHashAlgorithms.add(HashAlgorithmTags.SHA512);
+        sPreferredHashAlgorithms.add(HashAlgorithmTags.SHA384);
+        sPreferredHashAlgorithms.add(HashAlgorithmTags.SHA224);
+        sPreferredHashAlgorithms.add(HashAlgorithmTags.SHA1);
+        sPreferredHashAlgorithms.add(HashAlgorithmTags.RIPEMD160);
+
+        sPreferredCompressionAlgorithms.add(CompressionAlgorithmTags.ZLIB);
+        sPreferredCompressionAlgorithms.add(CompressionAlgorithmTags.BZIP2);
+        sPreferredCompressionAlgorithms.add(CompressionAlgorithmTags.ZIP);
+    }
+
+    /*
+     * Note: s2kcount is a number between 0 and 0xff that controls the
+     * number of times to iterate the password hash before use. More
+     * iterations are useful against offline attacks, as it takes more
+     * time to check each password. The actual number of iterations is
+     * rather complex, and also depends on the hash function in use.
+     * Refer to Section 3.7.1.3 in rfc4880.txt. Bigger numbers give
+     * you more iterations.  As a rough rule of thumb, when using
+     * SHA256 as the hashing function, 0x10 gives you about 64
+     * iterations, 0x20 about 128, 0x30 about 256 and so on till 0xf0,
+     * or about 1 million iterations. The maximum you can go to is
+     * 0xff, or about 2 million iterations.
+     * from http://kbsriram.com/2013/01/generating-rsa-keys-with-bouncycastle.html
+     *
+     * Bouncy Castle default: 0x60
+     * kbsriram proposes: 0xc0
+     * OpenKeychain: 0x90
+     */
+    public static final int SECRET_KEY_ENCRYPTOR_S2K_COUNT = 0x90;
+    public static final int SECRET_KEY_ENCRYPTOR_HASH_ALGO = HashAlgorithmTags.SHA256;
+    public static final int SECRET_KEY_ENCRYPTOR_SYMMETRIC_ALGO = SymmetricKeyAlgorithmTags.AES_256;
+    public static final int SECRET_KEY_SIGNATURE_HASH_ALGO = HashAlgorithmTags.SHA256;
+    // NOTE: only SHA1 is supported for key checksum calculations in OpenPGP,
+    // see http://tools.ietf.org/html/rfc488 0#section-5.5.3
+    public static final int SECRET_KEY_SIGNATURE_CHECKSUM_HASH_ALGO = HashAlgorithmTags.SHA1;
+
+    public static interface OpenKeychainSymmetricKeyAlgorithmTags extends SymmetricKeyAlgorithmTags {
+        public static final int USE_PREFERRED = -1;
+    }
+
+    public static interface OpenKeychainHashAlgorithmTags extends HashAlgorithmTags {
+        public static final int USE_PREFERRED = -1;
+    }
+
+    public static interface OpenKeychainCompressionAlgorithmTags extends CompressionAlgorithmTags {
+        public static final int USE_PREFERRED = -1;
+    }
+
+    public static int[] getAsArray(ArrayList<Integer> list) {
+        int[] array = new int[list.size()];
+        for (int i = 0; i < list.size(); i++) {
+            array[i] = list.get(i);
+        }
+        return array;
+    }
+}