1 files changed, 69 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..3ed1d9d11
--- /dev/null
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpConstants.java
@@ -0,0 +1,69 @@
+package org.sufficientlysecure.keychain.pgp;
+
+import org.spongycastle.bcpg.CompressionAlgorithmTags;
+import org.spongycastle.bcpg.HashAlgorithmTags;
+import org.spongycastle.bcpg.SymmetricKeyAlgorithmTags;
+
+public class PgpConstants {
+
+    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;
+    }
+
+    // most preferred is first
+    public static final int[] PREFERRED_SYMMETRIC_ALGORITHMS = new int[]{
+            SymmetricKeyAlgorithmTags.AES_256,
+            SymmetricKeyAlgorithmTags.AES_192,
+            SymmetricKeyAlgorithmTags.AES_128,
+            SymmetricKeyAlgorithmTags.TWOFISH
+    };
+
+    public static final int[] PREFERRED_HASH_ALGORITHMS = new int[]{
+            HashAlgorithmTags.SHA256,
+            HashAlgorithmTags.SHA512,
+            HashAlgorithmTags.SHA384,
+            HashAlgorithmTags.SHA224,
+            HashAlgorithmTags.RIPEMD160
+    };
+
+    public static final int[] PREFERRED_COMPRESSION_ALGORITHMS = new int[]{
+            CompressionAlgorithmTags.ZLIB,
+            CompressionAlgorithmTags.BZIP2,
+            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
+     * we use 0x90, a good trade-off between usability and security against offline attacks
+     */
+    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.
+    public static final int SECRET_KEY_SIGNATURE_CHECKSUM_HASH_ALGO = HashAlgorithmTags.SHA1;
+
+
+}