Added checksum address encoder.

hyperledger · Feb 26, 2018 · 8a0caa8 · 8a0caa8
1 parent 3738e4e
commit 8a0caa8
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diff --git a/crypto/src/main/java/org/web3j/crypto/Keys.java b/crypto/src/main/java/org/web3j/crypto/Keys.java
@@ -85,6 +85,32 @@ public static byte[] getAddress(byte[] publicKey) {
         return Arrays.copyOfRange(hash, hash.length - 20, hash.length);  // right most 160 bits
     }
 
+    /**
+     * Checksum address encoding as per
+     * <a href="https://github.com/ethereum/EIPs/blob/master/EIPS/eip-55.md">EIP-55</a>.
+     *
+     * @param address a valid hex encoded address
+     * @return hex encoded checksum address
+     */
+    public static String toChecksumAddress(String address) {
+        String lowercaseAddress = Numeric.cleanHexPrefix(address).toLowerCase();
+        String addressHash = Numeric.cleanHexPrefix(Hash.sha3String(lowercaseAddress));
+
+        StringBuilder result = new StringBuilder(lowercaseAddress.length() + 2);
+
+        result.append("0x");
+
+        for (int i = 0; i < lowercaseAddress.length(); i++) {
+            if (Integer.parseInt(String.valueOf(addressHash.charAt(i)), 16) >= 8) {
+                result.append(String.valueOf(lowercaseAddress.charAt(i)).toUpperCase());
+            } else {
+                result.append(lowercaseAddress.charAt(i));
+            }
+        }
+
+        return result.toString();
+    }
+
     public static byte[] serialize(ECKeyPair ecKeyPair) {
         byte[] privateKey = Numeric.toBytesPadded(ecKeyPair.getPrivateKey(), PRIVATE_KEY_SIZE);
         byte[] publicKey = Numeric.toBytesPadded(ecKeyPair.getPublicKey(), PUBLIC_KEY_SIZE);

diff --git a/crypto/src/test/java/org/web3j/crypto/KeysTest.java b/crypto/src/test/java/org/web3j/crypto/KeysTest.java
@@ -89,6 +89,36 @@ public void testGetAddressZeroPadded() {
                 equalTo(expected));
     }
 
+    @Test
+    public void testToChecksumAddress() {
+        // Test cases as per https://github.com/ethereum/EIPs/blob/master/EIPS/eip-55.md#test-cases
+
+        assertThat(Keys.toChecksumAddress("0xfb6916095ca1df60bb79ce92ce3ea74c37c5d359"),
+                is("0xfB6916095ca1df60bB79Ce92cE3Ea74c37c5d359"));
+
+        // All uppercase
+        assertThat(Keys.toChecksumAddress("0x52908400098527886E0F7030069857D2E4169EE7"),
+                is("0x52908400098527886E0F7030069857D2E4169EE7"));
+        assertThat(Keys.toChecksumAddress("0x8617E340B3D01FA5F11F306F4090FD50E238070D"),
+                is("0x8617E340B3D01FA5F11F306F4090FD50E238070D"));
+
+        // All lowercase
+        assertThat(Keys.toChecksumAddress("0xde709f2102306220921060314715629080e2fb77"),
+                is("0xde709f2102306220921060314715629080e2fb77"));
+        assertThat(Keys.toChecksumAddress("0x27b1fdb04752bbc536007a920d24acb045561c26"),
+                is("0x27b1fdb04752bbc536007a920d24acb045561c26"));
+
+        // Normal
+        assertThat(Keys.toChecksumAddress("0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"),
+                is("0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"));
+        assertThat(Keys.toChecksumAddress("0xfB6916095ca1df60bB79Ce92cE3Ea74c37c5d359"),
+                is("0xfB6916095ca1df60bB79Ce92cE3Ea74c37c5d359"));
+        assertThat(Keys.toChecksumAddress("0xdbF03B407c01E7cD3CBea99509d93f8DDDC8C6FB"),
+                is("0xdbF03B407c01E7cD3CBea99509d93f8DDDC8C6FB"));
+        assertThat(Keys.toChecksumAddress("0xD1220A0cf47c7B9Be7A2E6BA89F429762e7b9aDb"),
+                is("0xD1220A0cf47c7B9Be7A2E6BA89F429762e7b9aDb"));
+    }
+
     @Test
     public void testSerializeECKey() {
         assertThat(Keys.serialize(SampleKeys.KEY_PAIR), is(ENCODED));