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  Using keytool to create certificate chain

JDK provides a command line tool -- keytool to handle key and certificate generation. This tool has a set of options which can be used to generate keys, create certificates, import keys, install certificate and export certificates etc. In this tutorial, we will show how to create certificate chain using keytool. If you want to understand how to create certificate chain programmably, please refer to Generate certificate in Java -- Certificate chain. To begin, we first generate a key pair whi...

   JAVA,KEYTOOL,CERTIFICATE CHAIN,CERTIFICATE     2015-12-17 07:09:33

  Generate signed certificate from CSR in Java

In our previous tutorial, we have explained how to generate CSR which can be sent to CA for generating a signed certificate. In this tutorial, we will explain how to generate the signed certificate from CSR in Java. We will not use an actual CA but a self-signed certificate to act as a CA certificate. Since the CSR contains the subject information where a certificate needs to be generated and signed for. The key here is to extract the subject information from the CSR and then set it as the subje...

   JAVA,CSR,SIGN CERTIFICATE     2020-10-24 07:03:17

  One reason why mcrypt responds slowly

This morning one colleague came over and talked about one script which used mcrypt responded very slowly, the server configurations are fine. But the reason for the slowness is unknown. Here is one script which reproduces the issue: <?php $dmcryptText = "dummy"; $key = "foobar"; $size = mcrypt_get_iv_size(MCRYPT_BLOWFISH,MCRYPT_MODE_ECB); $iv = mcrypt_create_iv($size); //Take care $m = mcrypt_ecb(MCRYPT_BLOWFISH, $key, $dmcryptText, MCRYPT_DECRYPT, $iv); var_dump($m); When 20 requests of&...

   SOLUTION,SLOW,MCRYPT,RESPONSE,PHP     2012-09-27 12:03:16

  Different types of keystore in Java -- Windows-MY

Windows-MY is a type of keystore on Windows which is managed by the Windows operating system. It stores the user keys and certificates which can be used to perform cryptographic operations such as signature verification, data encryption etc. Since it's a kind of native keystore, Java doesn't have a general API to access it. To help Java applications access the keys and certificates stored in Windows-MY keystore, Java provides a separate API -- SunMSCAPI. The SunMSCAPI provider is ...

   JAVA,KEYSTORE,WINDOWS-MY,SUNMSCAPI     2016-01-09 05:45:59

  Creating Dynamic PDF files using HTML and PHP

There always arise a need for converting content from one file format to another one. Some may need to convert some text into HTML and some may need to convert some HTML content to an image format. The main reason for the need to convert from one file format to another is because the target file format is best suited for targeted medium where the content need to be displayed. The targeted medium may be an email, a printed hard copy or a web browser. The text format is best suited for sending ema...

   PHP,HTML,PDF,Conversion,Generate,Library     2011-11-18 12:10:53

  Implementation of +,-,*,/ with bitwise operator

There is a question asked on Stackoverflow : Divide a number by 3 without using *,/,+,-,% operators. This question is an Oracle interview question. Some people give excellent answers. You can go there and take a look. Usually we need to use bitwise operators to do this kind of implementations. Here I want to show you ways to implement +,-,*,/ with bitwise operators. A bitwise operation operates on one or more bit patterns or binary numerals at the level of their individual bits. It is a fast, pr...

   Bitwise operator,Shift,Add,Subtract,Multiplication,Division     2012-08-05 01:52:47

  Content based HTTP Cache

Browsers may cache the webpages we visited, when user types a URL on the address bar, the browser may cache the webpage returned from server while displaying it. If there is no update on the webpage, then next time when the browser requests the same page, it will not download the page again, instead it will load the cached page. If the website explicitly specify that the page is updated, then the browser will download the page again from the server. What's HTTP Cache? You may be familiar with th...

   HTTP Cache,Web crawler     2013-05-24 05:12:59

  Essential Rules To Protect Your Credit Card When Shopping Online

You have to protect yourself and your credit card online while shopping. There are a number of ways to do this, but some prove more technical than others. Your basic best defense includes sensible use and layers of protection. The best way to do this is to pick and choose which stores at which you charge purchases. You can reduce the chance of losing your card details to a thief by declining to allow the retailer to store your credit card. Use a password manager to save your passwords and make a...

   SECURITY,CREDIT CARD,MASTERCARD     2019-10-09 08:40:07

  Signature sign/verification demo in Java

Digital signature is commonly used in areas where data authentication and integrity are required. It is extremely important to have signature while transferring sensitive data from one peer to other peers through network since there might be malicious applications or man-in-the-middle attacks which may alter the data along the way. Java provides some APIs to generate and verify digital signature. One important class is Signature.  When generating the signature, a private key needs to be pa...

   SECURITY,JAVA,SIGNATURE     2015-11-21 09:48:12

  Fix --go_out: protoc-gen-go: plugins are not supported

When generating RPC code using proto file template in GoLang, one may face the issue like below when running the command protoc. Error: exit status 1 Output: --go_out: protoc-gen-go: plugins are not supported; use 'protoc --go-grpc_out=...' to generate gRPC See https://grpc.io/docs/languages/go/quickstart/#regenerate-grpc-code for more information. Normally this issue is caused because the version of protoc-gen-go being used is not correct. One way to fix the issue is to follow the instructions ...

   GOLANG,PROTO BUFFER,PLUGIN     2021-07-09 03:41:11

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