Crypto: new SigContext (WIP) (proposal #148)

core/java/src/net/i2p/crypto/SigContext.java

+package net.i2p.crypto;
+
+import java.security.spec.AlgorithmParameterSpec;
+
+import net.i2p.data.DataHelper;
+
+/**
+ * Defines the context for signing with personalized hashes.
+ * See proposal 148.
+ *
+ * @since 0.9.40
+ */
+public enum SigContext {
+
+    SC_NONE     (null),
+    SC_DATAGRAM ("sign_datagramI2P"),
+    SC_I2CP     ("I2CP_SessionConf"),
+    SC_NETDB    ("network_database"),
+    SC_NTCP     ("NTCP_1_handshake"),
+    SC_SSU      ("SSUHandshakeSign"),
+    SC_STREAMING("streaming_i2psig"),
+    SC_SU3      ("i2pSU3FileFormat"),
+    SC_TEST     ("test1234test5678"),
+
+    ;
+
+    private final SigContextSpec spec;
+
+    /**
+     * The 16 bytes for this type, or null for none
+     */
+    SigContext(String p) {
+        spec = new SigContextSpec(p);
+    }
+
+    /**
+     * The AlgorithmParameterSpec.
+     * Pass this as an argument in setParameter()
+     * to the Blake sign/verify engines.
+     */
+    public SigContextSpec getSpec() { return spec; }
+
+    /**
+     * The AlgorithmParameterSpec.
+     * Pass this as an argument in setParameter()
+     * to the Blake sign/verify engines.
+     */
+    public static class SigContextSpec implements AlgorithmParameterSpec {
+        private final byte[] b;
+
+        /**
+         * The 16 bytes for this type, or null for none
+         */
+        public SigContextSpec(String p) {
+            if (p != null) {
+                b = DataHelper.getASCII(p);
+                if (b.length != 16)
+                    throw new IllegalArgumentException();
+            } else {
+                b = null;
+            }
+        }
+
+        /**
+         * The 16 bytes for this type, or null for none
+         */
+        public byte[] getData() { return b; }
+    }
+}