# Ruby openssl

**URL:** <https://www.ruby-forum.com/t/ruby-openssl/163935>\
**Category:** Ruby\
**Created:** [March 26, 2009, 10:05am UTC](https://www.ruby-forum.com/t/ruby-openssl/163935 "2009-03-26T10:05:03Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![raghu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/b2d939/32.png) [@raghu](https://www.ruby-forum.com/u/raghu)\
**Post date:** [March 26, 2009, 10:05am UTC](https://www.ruby-forum.com/t/ruby-openssl/163935/1 "2009-03-26T10:05:03Z")

</div>

Hi,

Whats the ruby equivalent code for the following decryption code which  
is  
written in java.

1.7 Decrypt Token  
To be completed.  
1.7.1 Sample Java Code

import java.io.UnsupportedEncodingException;  
import java.net.URLDecoder;  
import java.security.GeneralSecurityException;  
import java.security.Key;  
import java.security.MessageDigest;  
import java.security.NoSuchAlgorithmException;  
import java.util.HashMap;  
import java.util.Map;

import javax.crypto.Cipher;  
import javax.crypto.Mac;  
import javax.crypto.spec.IvParameterSpec;  
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

public class TokenDecrypter {  
public static final String UTF8\_ENC = “UTF-8”;  
public byte [] hmacKey = null;  
public byte [] cipherKey = null;

// derive the hmac Key and the CipherKey with initialization using the  
Cert Id

public TokenDecrypter (String certId) throws NoSuchAlgorithmException  
{

```
MessageDigest md = MessageDigest.getInstance("SHA1");
byte [] masterKey = certId.getBytes();
byte [] baseHmac = new byte[masterKey.length +1];
baseHmac[0] = 1; //Use 1 for first bit in the key
System.arraycopy(masterKey, 0, baseHmac, 1, masterKey.length);
md.update(baseHmac);
hmacKey = md.digest();

byte [] baseCipher = new byte[masterKey.length +1];
baseCipher[0] = 0; //Use 0 for first bit in the key
System.arraycopy(masterKey, 0, baseCipher, 1, masterKey.length);
md.update(baseCipher);
byte [] hash = md.digest();

cipherKey = new byte[16]; //16byte = 128 bit encryption is used
    System.arraycopy(hash, 0, cipherKey, 0,16);

```

}

public String decrypt(String cipherTxt) throws  
GeneralSecurityException, UnsupportedEncodingException {

```
Mac hmacObj = Mac.getInstance("HMACSHA1");

// first Base64 Decode
byte[] bin = Base64.decodeBase64(cipherTxt.getBytes());

//seperate the hmac from the cipher
byte [] hmacReceived = new byte[20];
System.arraycopy(bin, bin.length-20, hmacReceived, 0, 20);

//seperate the cipher from the hmac
byte [] cipherBytes = new byte[bin.length-20];
System.arraycopy(bin, 0, cipherBytes, 0, cipherBytes.length);

// Hmac Verification Part
  Key hmacKey = new SecretKeySpec(this.hmacKey, "HMACSHA1");
  hmacObj.init(hmacKey);
  hmacObj.update(cipherBytes);
  byte actual[] = hmacObj.doFinal();

  if (actual.length != hmacReceived.length)
    throw new GeneralSecurityException("Integrity of the message

```

could not be verified");

```
  for (int i=0; i < actual.length; i++) {
      if (actual[i] != hmacReceived[i]) {
        throw new GeneralSecurityException("HMAC verification

```

failure");  
}  
}

```
  // Perform AES Decryption

  byte iv[] = new byte[16]; //CIPHER_BLOCK_SIZE
  System.arraycopy(cipherBytes, 0, iv, 0, iv.length);
  SecretKeySpec key = new SecretKeySpec(this.cipherKey, "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
  IvParameterSpec ivSpec = new IvParameterSpec(iv);
  cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);
  byte[] decrypted = cipher.doFinal(cipherBytes, 16 ,

```

cipherBytes.length-16); //discount the 16 byte IV

```
return new String(decrypted, UTF8_ENC).toString();

```

}

public Map\<String, String\> unwrap(String cypherText) throws  
GeneralSecurityException, UnsupportedEncodingException {  
String decryptedText = decrypt(cypherText);  
Map\<String, String\> keyValuePairs = getKeyValuePairs(decryptedText);  
return keyValuePairs;  
}

public Map\<String, String\> getKeyValuePairs(String decryptedText)  
throws UnsupportedEncodingException {  
Map\<String, String\> keyValuePairs = new HashMap\<String, String\>();

```
String[] items = decryptedText.split("[&=]");

for (int i = 0; i < items.length;) {
  String key = URLDecoder.decode(items[i++], UTF8_ENC);
  String value = URLDecoder.decode(items[i++], UTF8_ENC);
  keyValuePairs.put(key, value);
}

return keyValuePairs;

```

}

public static void main(String[] str) throws Exception {  
String myCertId = “xxxxxxx”;  
TokenDecrypter tokenDecrypter = new TokenDecrypter(myCertId);  
String token = null;[//request.getParameter](https://request.getParameter)(“st”); //Or tokenValue  
from EPI request

```
Map<String, String> keyValuePairs = tokenDecrypter.unwrap(token);

String userName = keyValuePairs.get("un");
String authToken = keyValuePairs.get("at");
String eiasToken = keyValuePairs.get("es");

```

}  
}

---

<div class="post-metadata">

**Author:** ![raghu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/b2d939/32.png) [@raghu](https://www.ruby-forum.com/u/raghu)\
**Post date:** [March 27, 2009, 3:51pm UTC](https://www.ruby-forum.com/t/ruby-openssl/163935/2 "2009-03-27T15:51:17Z")

</div>

[http://www.catb.org/~esr/faqs/smart-questions.html](http://www.catb.org/~esr/faqs/smart-questions.html)

Don’t post homework (or worse, commercial work) problems, because we  
won’t do them for you.

The documentation for ruby openssl can be found by typing “ruby openssl”  
into Google (it’s the first hit)

Example code can be found in the ruby distribution tarball in the  
sample/openssl directory, or at  
[http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/branches/ruby\_1\_8/sample/openssl/](http://svn.ruby-lang.org/cgi-bin/viewvc.cgi/branches/ruby_1_8/sample/openssl/)  
on the web.

The Ruby openssl code is just a very thin wrapper around the openssl  
library, so openssl’s C API documentation will tell you everything you  
need to know.

Then start writing code. Then when you have a specific problem, come  
back here. Narrow down the problem until you find a few lines of your  
Java code which produce a different result to the Ruby code you have  
written.

Adding debugging output to show that the conditions are the same in both  
pieces of code _before_ this snippet runs, but different _after_ it  
runs. Then if you can’t work out why one behaves differently to the  
other, post the two pieces of code here together with the start and end  
debugging output.