Develop Reference

Cipher functions:EVP_DecryptFinal_ex:DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH

Im trying to implement AES in an Android application. The server is a PHP server.
This is the AES code :
public class AES{
private String SecretKey = "89432hjfsd891787";
private String iv = "fedcba9876543210";
private IvParameterSpec ivspec;
private SecretKeySpec keyspec;
private Cipher cipher;
public AES()
{
ivspec = new IvParameterSpec(iv.getBytes());
keyspec = new SecretKeySpec(SecretKey.getBytes(), "AES");
try {
cipher = Cipher.getInstance("AES/CBC/NoPadding");
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public byte[] encrypt(String text) throws Exception
{
if(text == null || text.length() == 0)
throw new Exception("Empty string");
byte[] encrypted = null;
try {
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
encrypted = cipher.doFinal(padString(text).getBytes());
} catch (Exception e)
{
throw new Exception("[encrypt] " + e.getMessage());
}
return encrypted;
}
public byte[] decrypt(String code) throws Exception
{
if(code == null || code.length() == 0)
throw new Exception("Empty string");
byte[] decrypted = null;
try {
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
decrypted = cipher.doFinal(hexToBytes(code));
} catch (Exception e)
{
throw new Exception("[decrypt] " + e.getMessage());
}
return decrypted;
}
public static String bytesToHex(byte[] data)
{
if (data==null)
{
return null;
}
int len = data.length;
String str = "";
for (int i=0; i<len; i++) {
if ((data[i]&0xFF)<16)
str = str + "0" + java.lang.Integer.toHexString(data[i]&0xFF);
else
str = str + java.lang.Integer.toHexString(data[i]&0xFF);
}
return str;
}
public static byte[] hexToBytes(String str) {
if (str==null) {
return null;
} else if (str.length() < 2) {
return null;
} else {
int len = str.length() / 2;
byte[] buffer = new byte[len];
for (int i=0; i<len; i++) {
buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
}
return buffer;
}
}
private static String padString(String source)
{
char paddingChar = ' ';
int size = 16;
int x = source.length() % size;
int padLength = size - x;
for (int i = 0; i < padLength; i++) {
source += paddingChar;
}
return source;
}
}
I get an error while decrypting the incoming string : Cipher functions:EVP_DecryptFinal_ex:DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH
How do i go about this?

Manually padding the String representation of the plaintext with spaces is not a good padding mechanism. Instead, you should use AES/CBC/PKCS5Padding which will handle the padding as prescribed in PKCS #5/#7.
You should also:
generate a unique IV per encryption operation rather than re-using the same value for all messages
Use an authenticated mode of operation (GCM, HMAC/SHA-256 MAC over cipher text, etc.)
Store the key in hexadecimal representation of the raw bytes rather than an ASCII/UTF-8 String encoding (not specified in your code)
Encode the cipher text in Base64 or Hex before serializing/transmitting. Encoding errors can contribute to padding exceptions during decryption.

How to write a hash function in Android similar to the Python function?

I am currently developing a distributed system application. I want to verify a Python generated hash in the Android application. I have a python method to do hashing in given string variables.
This is the python function and it works well.
hash_value = hashlib.sha1("PARAMETER123".encode("UTF-8")).hexdigest()
I want to implement the same function in my Android application. I hope some expert can help as soon as possible.

You can try the following code snippet,
String text = "PARAMETER123";
MessageDigest md = MessageDigest.getInstance("SHA-1");
byte[] textBytes = text.getBytes("UTF-8");
md.update(textBytes, 0, textBytes.length);
byte[] sha1hash = md.digest();
String encrypted_text = = convertToHex(sha1hash);
and the convertToHex() method
private static String convertToHex(byte[] data) {
StringBuilder buf = new StringBuilder();
for (byte b : data) {
int halfbyte = (b >>> 4) & 0x0F;
int two_halfs = 0;
do {
buf.append((0 <= halfbyte) && (halfbyte <= 9) ? (char) ('0' + halfbyte) : (char) ('a' + (halfbyte - 10)));
halfbyte = b & 0x0F;
} while (two_halfs++ < 1);
}
return buf.toString();
}
This will convert a UTF-8 based text into a SHA1 hex.
Reference: https://stackoverflow.com/a/5980789/2506025

Here is a simple SHA1 method for Java:
String sha1Hash( String toHash )
{
String hash = null;
try
{
MessageDigest digest = MessageDigest.getInstance( "SHA-1" );
byte[] bytes = toHash.getBytes("UTF-8");
digest.update(bytes, 0, bytes.length);
bytes = digest.digest();
// This is ~55x faster than looping and String.formating()
hash = bytesToHex( bytes );
}
catch( NoSuchAlgorithmException e )
{
e.printStackTrace();
}
catch( UnsupportedEncodingException e )
{
e.printStackTrace();
}
return hash;
}
// http://stackoverflow.com/questions/9655181/convert-from-byte-array-to-hex-string-in-java
final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
public static String bytesToHex( byte[] bytes )
{
char[] hexChars = new char[ bytes.length * 2 ];
for( int j = 0; j < bytes.length; j++ )
{
int v = bytes[ j ] & 0xFF;
hexChars[ j * 2 ] = hexArray[ v >>> 4 ];
hexChars[ j * 2 + 1 ] = hexArray[ v & 0x0F ];
}
return new String( hexChars );
}
You can include those methods and call sha1hash.

how to encode pass with sha1 and Base64?

I need provide hashing password with sha1 and Base64 like next:
base64(sha1(password))
here is what i tried for:
private static String convertToHex(byte[] data) {
StringBuffer buf = new StringBuffer();
for (int i = 0; i < data.length; i++) {
int halfbyte = (data[i] >>> 4) & 0x0F;
int two_halfs = 0;
do {
if ((0 <= halfbyte) && (halfbyte <= 9)) {
buf.append((char) ('0' + halfbyte));
}
else {
buf.append((char) ('a' + (halfbyte - 10)));
}
halfbyte = data[i] & 0x0F;
} while(two_halfs++ < 1);
}
return buf.toString();
}
public static String SHA1(String password) throws NoSuchAlgorithmException, UnsupportedEncodingException {
MessageDigest md = MessageDigest.getInstance("SHA-1");
md.update(password.getBytes("iso-8859-1"), 0, password.length());
byte[] sha1hash = md.digest();
return convertToHex(sha1hash);
}
and than :
String encodedPass = Base64.encodeToString(password.getBytes(), Base64.DEFAULT);
but this doesn't work correctly...
Maybe there some mistake or some much easier way to do it?

the problem was next:
convertToHex(sha1hash) - return string, but for correct work of Base64 I was needed to put byte [] here:
Base64.encodeToString(byte[], Base64.DEFAULT);
so solution is pretty simple:
public static String encodePassword(String password) throws NoSuchAlgorithmException, UnsupportedEncodingException {
String result;
MessageDigest md = MessageDigest.getInstance("SHA-1");
md.update(password.getBytes("iso-8859-1"), 0, password.length());
byte[] sha1hash = md.digest();
result = Base64.encodeToString(sha1hash, Base64.DEFAULT);
result = result.substring(0, result.length()-1);
return result;
}

Converting a string sent via SMS into RSA Public/Private key in android

I've been working on it for several days but without success, I' m doing SMS encryption in android using RSA encryption, the problem is how can I convert a String to public key and use it for encryption, I'm sending the publicKey converted into String via SMS but I'm not able to get the key back.
This is how my algorithm works but when I send "puk" as a string via Sms and make encryption it doesn't work anymore!!! plz help me . . .
private final static String RSA = "RSA";
public static PublicKey uk;
public static PrivateKey rk;
public static String puk;
public static void generateKey() throws Exception
{
KeyPairGenerator gen = KeyPairGenerator.getInstance(RSA);
gen.initialize(128, new SecureRandom());
KeyPair keyPair = gen.generateKeyPair();
uk = keyPair.getPublic();
rk = keyPair.getPrivate();
puk = uk.toString();
}
private static byte[] encrypt(String text, PublicKey pubRSA) throws Exception
{
Cipher cipher = Cipher.getInstance(RSA);
cipher.init(Cipher.ENCRYPT_MODE, pubRSA);
return cipher.doFinal(text.getBytes());
}
public final static String encrypt(String text)
{
try {
return byte2hex(encrypt(text, uk));
}
catch(Exception e)
{
e.printStackTrace();
}
return null;
}
public final static String decrypt(String data)
{
try{
String text = new String(decrypt(hex2byte(data.getBytes())));
return text+" OK";
}
catch (Exception e)
{
return "Error: "+e;
}
}
private static byte[] decrypt(byte[] src) throws Exception
{
Cipher cipher = Cipher.getInstance(RSA);
cipher.init(Cipher.DECRYPT_MODE, rk);
return cipher.doFinal(src);
}
public static String byte2hex(byte[] b)
{
String hs = "";
String stmp = "";
for (int n = 0; n < b.length; n ++)
{
stmp = Integer.toHexString(b[n] & 0xFF);
if (stmp.length() == 1)
hs += ("0" + stmp);
else
hs += stmp;
}
return hs.toUpperCase();
}
public static byte[] hex2byte(byte[] b)
{
if ((b.length % 2) != 0)
throw new IllegalArgumentException("hello");
byte[] b2 = new byte[b.length / 2];
for (int n = 0; n < b.length; n += 2)
{
String item = new String(b, n, 2);
b2[n/2] = (byte)Integer.parseInt(item, 16);
}
return b2;
}

How to generate HMAC-SHA1 Signature in android?

This is my base String:
String args ="oauth_consumer_key="+enc(consumerkey) +
"&oauth_nonce="+enc(generateNonce()) +
"&oauth_signature_method=HMAC-SHA1" +
"&oauth_timestamp="+ timestamp +
"&oauth_token="+enc(Home.consToken) +
"&oauth_verifier="+verifier+"&oauth_version=1.0";
String base ="POST&"+enc("https://api.linkedin.com/uas/oauth /accessToken") +"&"+ enc(args);
String signature =computeHmac(base,consumer_secret+"&"+secretToken);
This is my Header:
String header = "OAuth " +
"oauth_consumer_key=\""+ enc(consumerkey)+ "\"," +
"oauth_nonce=\""+ enc(generateNonce()) + "\"," +
"oauth_signature_method=\"HMAC-SHA1\"," +
"oauth_timestamp=\""+ timestamp + "\"," +
"oauth_token=\""+Home.consToken + "\"," +
"oauth_signature=\""+enc(signature)+"\","+
"oauth_verifier=\""+verifier +"\","+
"oauth_version=\""+1.0+"\"" ;
I am using following method to generate Signature:
public String computeHmac(String baseString, String key)
throws NoSuchAlgorithmException, InvalidKeyException, IllegalStateException, UnsupportedEncodingException
{
Mac mac = Mac.getInstance("HmacSHA1");
SecretKeySpec secret = new SecretKeySpec(key.getBytes(), mac.getAlgorithm());
mac.init(secret);
byte[] digest = mac.doFinal(baseString.getBytes());
byte[] result=Base64.encodeBase64(digest);
return new String(result);
}
while executing this code i am getting the following error...
oauth_problem=signature_invalid&
oauth_problem_advice=com.linkedin.security.auth.pub.LoginDeniedInvalidAuthTokenException
can anybody help me out this?
Thanks...

Femi's answer is absolutely correct, however, it wasn't obvious for me what exactly is intval(b). As i understood it's b & 0xFF.
Also I applied some optimizations (that I found here) and here is my code:
private static String hmacSha1(String value, String key)
throws UnsupportedEncodingException, NoSuchAlgorithmException,
InvalidKeyException {
String type = "HmacSHA1";
SecretKeySpec secret = new SecretKeySpec(key.getBytes(), type);
Mac mac = Mac.getInstance(type);
mac.init(secret);
byte[] bytes = mac.doFinal(value.getBytes());
return bytesToHex(bytes);
}
private final static char[] hexArray = "0123456789abcdef".toCharArray();
private static String bytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
int v;
for (int j = 0; j < bytes.length; j++) {
v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars);
}

Messy, but I'm using this:
static String hash_hmac(String type, String value, String key)
{
try {
javax.crypto.Mac mac = javax.crypto.Mac.getInstance(type);
javax.crypto.spec.SecretKeySpec secret = new javax.crypto.spec.SecretKeySpec(key.getBytes(), type);
mac.init(secret);
byte[] digest = mac.doFinal(value.getBytes());
StringBuilder sb = new StringBuilder(digest.length*2);
String s;
for (byte b : digest){
s = Integer.toHexString(intval(b));
if(s.length() == 1) sb.append('0');
sb.append(s);
}
return sb.toString();
} catch (Exception e) {
android.util.Log.v("TAG","Exception ["+e.getMessage()+"]", e);
}
return "";
}
You then invoke it like this:
hash_hmac("HmacSHA1", value, key);