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Thread: invalid encoding for signature

  1. #1
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    Default invalid encoding for signature

    Hi every body!

    I am writing a java code which creates some signature using SHA1 and I want to store the signature in db. I used MYSQL and I put the signature in a column by VARCHAR type. when I fetch the signature to verify it, the 'Verification=signature.verify(Sign);" make an error which is :
    invalid encoding for signature

    Variable type of Sign is byte[]. but I fetch String type from DB. then I converted it to byte[] by :
    Sign=rs.getString("sign").getBytes();

    I think this conversion spoils the signature.What shall I do? How can I make the encoding proper?

    this is the code:

     //create signature
     
            Signature signature = Signature.getInstance("DSA");
            signature.initSign(privkey);
            signature.update(datatoSign);
            byte[] Sign=signature.sign();
     
           mystatment.executeUpdate("UPDATE mytable SET sign = '"+Sign+"' ");
     
    //Now I a will fetch the tuple AND verfiy the signature by public key
     
    SQL="SELECT * FROM notebooks "
    rs=(stat.executeQuery(SQL));
    Sign=rs.getString("sign").getBytes();
     
     
    boolean Verification;
    signature.initVerify(pubkey);
    signature.update(datatoSign);
    Verification=signature.verify(Sign); //--------------this the error generating line


    I am looking to here from you


  2. #2
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    Default Re: invalid encoding for signature

    You're making it too difficult. Use something like Commons Codec, to base64 encode your string before you save it and base64 decode when you read it out of the database. Converting from byte[] to String between your database and your code can introduce conversion errors based on different character sets - which is what you suspect.

    Creating a base64 encoded String looks something like:

    byte[] theArray = ...;
    String hash = new String( Base64.encodeBase64( theArray ) );
    Need Java help? Check out the HotJoe Java Help forums!

  3. The Following User Says Thank You to stdunbar For This Useful Post:

    Silvery (July 2nd, 2012)

  4. #3
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    Default Re: invalid encoding for signature

    Yes, you are right. So thanks for your useful comment.

    I changed the code in this form:

     //create signature
     
            Signature signature = Signature.getInstance("DSA");
            signature.initSign(privkey);
            signature.update(datatoSign);
            byte[] Sign=signature.sign();
    //encode the Sign to Base64 
    String MySign=new String (Base64.encode(Sign));
     
           mystatment.executeUpdate("UPDATE mytable SET sign = '"+MySign+"' ");
     
    //Now I a will fetch the tuple AND verfiy the signature by public key
     
    SQL="SELECT * FROM notebooks "
    rs=(stat.executeQuery(SQL));
     
    //decode the fetched signature from DB 
    TheSign=Base64.decode(rs.getString("sign"));
     
    boolean Verification;
    signature.initVerify(pubkey);
    signature.update(datatoSign);
    Verification=signature.verify(TheSign);

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