**To Generate Private Key**
```console
openssl genrsa -out privatekey.pem 2048
```

**To Sign**
```console
openssl dgst -sha256 -sign privatekey.pem -out data.txt.signature data.txt
```

**To Generate The Public Key**

`dgst -verify` requires the public key
```console
openssl rsa -in privatekey.pem -outform PEM -pubout -out publickey.pem
```
**To Verify**
```console
openssl dgst -sha256 -verify publickey.pem -signature data.txt.signature data.txt
```
- In case of success: prints `&quot;Verified OK&quot;`, return code `0`
- In case of failure: prints `&quot;Verification Failure&quot;`, return code `1`

Yes, the [dgst][1] and [rsautl][2] component of OpenSSL can be used to compute a signature given an RSA key pair.

### Signing: ###

    openssl dgst -sha256 data.txt &gt; hash
    openssl rsautl -sign -inkey privatekey.pem -keyform PEM -in hash &gt;signature


### Verifying just the signature: ###

    openssl rsautl -verify -inkey publickey.pem -pubin -keyform PEM -in signature


*Update: Capturing Reto&#39;s comments from below because this is an important nuance.  Presumably if you are going to the trouble to verify, you want to know the signature was produced on the plaintext to which it is attached:* 

This might sound obvious for some but: Be aware, `rsautl verify` just decrypts the file `signature`. The output of this call is guaranteed to be produced by the owner of the private key, but beside that nothing else is being checked. So to actually verify the consistency of `data.txt` you have to regenerate the digest and then compare it against the output of `openssl rsautl -verify`.

### Verifying that the owner of the private key does vouch for `data.txt`: ###

    openssl dgst -sha256 -verify publickey.pem -signature signature data.txt

For this operation, _openssl_ requires the public key, the signature, and the message.

  [1]: http://www.openssl.org/docs/apps/dgst.html#
  [2]: http://www.openssl.org/docs/apps/rsautl.html

To **digitally sign** document in openssl it will work 

For this first your certificate should be trusted
it would be look like this 

    -----BEGIN TRUSTED CERTIFICATE-----
    MIIDbjCCAlYCCQCOyunl25ProDANBgkqhkiG9w0BAQUFADB5MQswCQYDVQQGEwJJ
    ...
    -----END TRUSTED CERTIFICATE-----

Then use following command 

    smime -sign -signer certificate.pem -inkey private.key -in test.txt \
        -out test1.txt -from ashish -to singhal

    insert into OPT (email, campaign_id) values(&#39;mom@cox.net&#39;,100)
    where not exists( select * from OPT where (email =&quot;mom@cox.net&quot; and campaign_id =100)) ;

&gt; Error report: SQL Error: ORA-00933: SQL command not properly ended
&gt; 00933. 00000 -  &quot;SQL command not properly ended&quot;
&gt; *Cause:    
&gt; *Action:

how to insert a new row if it doesn&#39;t exists in Oracle?

Oracle insert if not exists statement

Is it possible to set the font for all the TextViews in a activity? I can set the font for a single textView by using: 

        TextView tv=(TextView)findViewById(R.id.textView1); 
        Typeface face=Typeface.createFromAsset(getAssets(), &quot;font.ttf&quot;); 
        tv.setTypeface(face);

But I would like to change all the textViews at once, instead of setting it manually for every textView, any info would be appreciated!

Set font for all textViews in activity?

Is there a way to digitally sign a x509 certificate or any document using openssl?

Digital signature for a file using openssl

<p>Is there a way to digitally sign a x509 certificate or any document using openssl?</p>


I&#39;m currently a student and I&#39;m studying PHP, I&#39;m trying to make a simple encrypt/decrypt of data in PHP. I made some online research and some of them were quite confusing(at least for me).

Here&#39;s what I&#39;m trying to do:

I have a table consisting of these fields **(UserID,Fname,Lname,Email,Password)**

What I want to have is have the all fields encrypted and then be decrypted(Is it possible to use `sha256` for encryption/decryption, if not any encryption algorithm)

Another thing I want to learn is how to create a one way `hash(sha256)` combined with a good &quot;salt&quot;.
(Basically I just want to have a simple implementation of encryption/decryption, `hash(sha256)+salt)
`
Sir/Ma&#39;am, your answers would be of great help and be very much appreciated. Thank you++

How to encrypt/decrypt data in php?

My team got handed over some server side code (in Java) that generates random tokens and I have a question regarding the same -

The purpose of these tokens is fairly sensitive - used for session id, password reset links etc. So they do need to be cryptographically random to avoid somebody guessing them or brute force them feasibly. The token is a &quot;long&quot; so it is 64 bits long.

The code currently uses the `java.util.Random` class to generate these tokens. The [documentation][1] for `java.util.Random` clearly states the following: 

&gt; Instances of java.util.Random are not cryptographically secure. Consider instead using SecureRandom to get a cryptographically secure pseudo-random number generator for use by security-sensitive applications.

However, the way the code is currently using `java.util.Random` is this - It instantiates the `java.security.SecureRandom` class and then uses the `SecureRandom.nextLong()` method to obtain the seed that is used for instantiating the `java.util.Random`class. Then it uses `java.util.Random.nextLong()` method to generate the token.


So my question now - Is it still insecure given that the `java.util.Random` is being seeded using `java.security.SecureRandom`? Do I need to modify the code so that it uses `java.security.SecureRandom` exclusively to generate the tokens?

 Currently the code seed&#39;s the `Random` once at startup


  [1]: https://docs.oracle.com/javase/7/docs/api/java/util/Random.html

Difference between java.util.Random and java.security.SecureRandom

I&#39;m using a [Java scrypt library](https://github.com/wg/scrypt) for password storage. It calls for an `N`, `r` and `p` value when I encrypt things, which its documentation refers to as &quot;CPU cost&quot;, &quot;memory cost&quot; and &quot;parallelization cost&quot; parameters. Only problem is, I don&#39;t actually know what they specifically mean, or what good values would be for them; perhaps they correspond somehow to the -t, -m and -M switches on [Colin Percival&#39;s original app](http://www.tarsnap.com/scrypt.html)?

Does anyone have any suggestions for this? The library itself lists N = 16384, r = 8 and p = 1, but I don&#39;t know if this is strong or weak or what.

What are optimal scrypt work factors?

For a payment provider, I need to calculate a hash-based message authentication code, using HMAC-SHA256. That is causing me quite a bit of trouble.

The payment provider gives two examples of orrectly calculated authentication code in pseudo-code. All keys are in hex.

###Method 1 

    key = 57617b5d2349434b34734345635073433835777e2d244c31715535255a366773755a4d70532a5879793238235f707c4f7865753f3f446e633a21575643303f66
    message = &quot;amount=100&amp;currency=EUR&quot;
    MAC = HMAC-SHA256( hexDecode(key), message )
    result = b436e3e86cb3800b3864aeecc8d06c126f005e7645803461717a8e4b2de3a905

###Method 2

    message = &quot;amount=100&amp;currency=EUR&quot;
    Ki = 61574d6b157f757d02457573556645750e0341481b127a07476303136c005145436c7b46651c6e4f4f040e1569464a794e534309097258550c17616075060950
    Ko = 0b3d27017f151f17682f1f193f0c2f1f64692b227178106d2d096979066a3b2f2906112c0f760425256e647f032c2013243929636318323f667d0b0a1f6c633a
    MAC = SHA256( hexDecode(Ko) + SHA256( hexDecode(Ki) + message ) )
    result = b436e3e86cb3800b3864aeecc8d06c126f005e7645803461717a8e4b2de3a905

I tried to write the code to do this, after doing some research, but I keep coming up with different results.





    private static void Main(string[] args)
        {
            var key = &quot;57617b5d2349434b34734345635073433835777e2d244c31715535255a366773755a4d70532a5879793238235f707c4f7865753f3f446e633a21575643303f66&quot;;
            var ki = &quot;61574d6b157f757d02457573556645750e0341481b127a07476303136c005145436c7b46651c6e4f4f040e1569464a794e534309097258550c17616075060950&quot;;
            var ko = &quot;0b3d27017f151f17682f1f193f0c2f1f64692b227178106d2d096979066a3b2f2906112c0f760425256e647f032c2013243929636318323f667d0b0a1f6c633a&quot;;
            var mm = &quot;amount=100&amp;currency=EUR&quot;;

            var result1 = CalcHMACSHA256Hash(HexDecode(key), mm);

            var result2 = CalcSha256Hash(string.Format(&quot;{0}{1}&quot;, HexDecode(ko), CalcSha256Hash(HexDecode(ki) + mm)));

            Console.WriteLine(&quot;Expected: b436e3e86cb3800b3864aeecc8d06c126f005e7645803461717a8e4b2de3a905&quot;);
            Console.WriteLine(&quot;Actual 1: &quot; + result1);
            Console.WriteLine(&quot;Actual 2: &quot; + result2);

            Console.WriteLine(&quot;------------------------------&quot;);
            Console.ReadKey();

        }

        private static string HexDecode(string hex)
        {
            var sb = new StringBuilder();
            for (int i = 0; i &lt;= hex.Length - 2; i += 2)
            {
                sb.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hex.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
            }
            return sb.ToString();
        }

        private static string CalcHMACSHA256Hash(string plaintext, string salt)
        {
            string result = &quot;&quot;;
            var enc = Encoding.Default;
            byte[]
            baText2BeHashed = enc.GetBytes(plaintext),
            baSalt = enc.GetBytes(salt);
            System.Security.Cryptography.HMACSHA256 hasher = new HMACSHA256(baSalt);
            byte[] baHashedText = hasher.ComputeHash(baText2BeHashed);
            result = string.Join(&quot;&quot;, baHashedText.ToList().Select(b =&gt; b.ToString(&quot;x2&quot;)).ToArray());
            return result;
        }


        public static string CalcSha256Hash(string input)
        {
            SHA256 sha256 = new SHA256Managed();
            byte[] sha256Bytes = Encoding.Default.GetBytes(input);
            byte[] cryString = sha256.ComputeHash(sha256Bytes);
            string sha256Str = string.Empty;
            for (int i = 0; i &lt; cryString.Length; i++)
            {
                sha256Str += cryString[i].ToString(&quot;x2&quot;);
            }
            return sha256Str;
        }


And this is the result I get:

    Expected: b436e3e86cb3800b3864aeecc8d06c126f005e7645803461717a8e4b2de3a905
    Actual 1: 421ce16f2036bb9f2a3770c16f01e9220f0232d45580584ca41768fd16c15fe6
    Actual 2: 290f14398bf8c0959dfc963e2fd9c377534c6fec1983025d2ab192382f132b92

So with none of the two methods, I can get the result the provider example wants.

**What am I missing here? Is it encoding? Is my hexDecode screwed up?**

Test tool from payment provider: http://tech.dibs.dk/dibs_api/other_features/hmac_tool/

PHP sample code: http://tech.dibspayment.com/dibs_api/other_features/mac_calculation/

Calculating HMACSHA256 using c# to match payment provider example

I have been searching the Internet for ***good*** c++ AES code sample/tutorial that teaches the basics of the encryption technology and the use of the Library but so far I have had no luck getting decent material.

good: Easy to understand (Just the basics for on the go study).

Example of AES using Crypto++

I&#39;ve generated a private key with:

    openssl genrsa [-out file] –des3

After this I&#39;ve generated a public key with:

    openssl rsa –pubout -in private.key [-out file]

I want to sign some messages with my private key, and verify some other messages with my public key, using code like this:

    public String sign(String message) throws SignatureException{
        try {
            Signature sign = Signature.getInstance(&quot;SHA1withRSA&quot;);
            sign.initSign(privateKey);
            sign.update(message.getBytes(&quot;UTF-8&quot;));
            return new String(Base64.encodeBase64(sign.sign()),&quot;UTF-8&quot;);
        } catch (Exception ex) {
            throw new SignatureException(ex);
        }
    }

    public boolean verify(String message, String signature) throws SignatureException{
        try {
            Signature sign = Signature.getInstance(&quot;SHA1withRSA&quot;);
            sign.initVerify(publicKey);
            sign.update(message.getBytes(&quot;UTF-8&quot;));
            return sign.verify(Base64.decodeBase64(signature.getBytes(&quot;UTF-8&quot;)));
        } catch (Exception ex) {
            throw new SignatureException(ex);
        }
    }

I found a solution to convert my private key to PKCS8 format and load it. It works with some code like this:

    public PrivateKey getPrivateKey(String filename) throws Exception {

        File f = new File(filename);
        FileInputStream fis = new FileInputStream(f);
        DataInputStream dis = new DataInputStream(fis);
        byte[] keyBytes = new byte[(int) f.length()];
        dis.readFully(keyBytes);
        dis.close();
        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory kf =
                KeyFactory.getInstance(&quot;RSA&quot;);
        return kf.generatePrivate(spec);
    }

And finally my question is: **How do I load my RSA Public Key from a file?**

I think maybe I need to convert my public key file to x509 format, and use `X509EncodedKeySpec`. But how can I do this?

Load RSA public key from file

I am running Windows Vista and am attempting to connect via https to upload a file in a multi part form but I am having some trouble with the local issuer certificate. I am just trying to figure out why this isnt working now, and go back to my cURL code later after this is worked out. Im running the command:

    openssl s_client -connect connect_to_site.com:443

It gives me an digital certificate from VeriSign, Inc., but also shoots out an error:

    Verify return code: 20 (unable to get local issuer certificate)

What is the local issuer certificate? Is that a certificate from my own computer? Is there a way around this? I have tried using -CAfile mozilla.pem file but still gives me same error.

OpenSSL Verify return code: 20 (unable to get local issuer certificate)

I am writing a small piece of code which reads public and private key stored in .pem file. I am using the following commands to generate the keys.  

Below command to generate pair of key.  
 

       $openssl genrsa -out mykey.pem 2048
This command to generate the private key

    $openssl pkcs8 -topk8 -inform PEM -outform PEM -in mykey.pem \
        -out private_key.pem -nocrypt
and this command to get the public key.  

    $ openssl rsa -in mykey.pem -pubout -outform DER -out public_key.der
I have written two methods which reads the private key and public key respectively.

       public  PrivateKey getPemPrivateKey(String filename, String algorithm) throws Exception {
          File f = new File(filename);
          FileInputStream fis = new FileInputStream(f);
          DataInputStream dis = new DataInputStream(fis);
          byte[] keyBytes = new byte[(int) f.length()];
          dis.readFully(keyBytes);
          dis.close();
          
          String temp = new String(keyBytes);
          String privKeyPEM = temp.replace(&quot;-----BEGIN PRIVATE KEY-----\n&quot;, &quot;&quot;);
          privKeyPEM = privKeyPEM.replace(&quot;-----END PRIVATE KEY-----&quot;, &quot;&quot;);
          //System.out.println(&quot;Private key\n&quot;+privKeyPEM);
    
          Base64 b64 = new Base64();
          byte [] decoded = b64.decode(privKeyPEM);
         
          PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(decoded);
          KeyFactory kf = KeyFactory.getInstance(algorithm);
          return kf.generatePrivate(spec);
          }
       
       public  PublicKey getPemPublicKey(String filename, String algorithm) throws Exception {
          File f = new File(filename);
          FileInputStream fis = new FileInputStream(f);
          DataInputStream dis = new DataInputStream(fis);
          byte[] keyBytes = new byte[(int) f.length()];
          dis.readFully(keyBytes);
          dis.close();
          
          String temp = new String(keyBytes);
          String publicKeyPEM = temp.replace(&quot;-----BEGIN PUBLIC KEY-----\n&quot;, &quot;&quot;);
          publicKeyPEM = publicKeyPEM.replace(&quot;-----END PUBLIC KEY-----&quot;, &quot;&quot;);
          
    
          Base64 b64 = new Base64();
          byte [] decoded = b64.decode(publicKeyPEM);
         
          X509EncodedKeySpec spec =
                new X509EncodedKeySpec(decoded);
          KeyFactory kf = KeyFactory.getInstance(algorithm);
          return kf.generatePublic(spec);
          }
I feel like this is a naive way of doing it. I couldn&#39;t get any better way of doing it over internet. Can anyone suggest me what is the best way of writing the same code to handle the generic cases. I don&#39; want to use any kind of third party library.   
I have very basic knowledge of singing/encrypting and hardly use any java security APIs. So if I am not making sense somewhere then please point out.


How to read .pem file to get private and public key

I had a look at [this][1] question, and wanted to do it for myself. When I ran this code (taken straight from [this answer][2]):

	$textToEncrypt = &quot;My super secret information.&quot;;
	$encryptionMethod = &quot;AES-256-CBC&quot;;  // AES is used by the U.S. gov&#39;t to encrypt top secret documents.
	$secretHash = &quot;25c6c7ff35b9979b151f2136cd13b0ff&quot;;

	//To encrypt
	$encryptedMessage = openssl_encrypt($textToEncrypt, $encryptionMethod, $secretHash, &#39;1234567812345678&#39;);

	//To Decrypt
	$decryptedMessage = openssl_decrypt($encryptedMessage, $encryptionMethod, $secretHash);

	//Result
	echo &quot;Encrypted: $encryptedMessage &lt;br&gt;Decrypted: $decryptedMessage&quot;;

However I get the warning
    
    openssl_encrypt(): Using an empty Initialization Vector (iv) is potentially insecure and not recommended

So I went and had a look at the [docs][3], but there &#39;is no documentation&#39;. I found this [comment][4], but still no mention of what the Initialization Vector should be and how I should use it. Can anyone enlighten me?

I know I could have done some more Googleing, but Stackoverflow comes up first in so many search results I thought this question might be useful to anyone else who was having this problem.


  [1]: https://stackoverflow.com/questions/1391132/two-way-encryption-in-php
  [2]: https://stackoverflow.com/a/6639179/962144
  [3]: http://www.php.net/manual/en/function.openssl-encrypt.php
  [4]: http://www.php.net/manual/en/function.openssl-encrypt.php#99188

Use of Initialization Vector in openssl_encrypt

While generating the private key using this command

    genrsa -out my-prvkey.pem 1024
            
It throws the error like below 

&gt; Loadind &#39;screen&#39; into random state -done Generating RSA private
&gt; key,1024 bit long modulus
&gt; .........................................+++++++
&gt; ...........................+++++++++ unable to write &#39;random state&#39; e
&gt; is 65537 (0*10001)

This makes any problem while creating a public certificate. I&#39;m running this command in windows. Can anyone help me for the fix?


How to fix &quot;unable to write &#39;random state&#39; &quot; in openssl

I am implementing a demo for RSA Encryption and Decryption in Android. I can Perform Encryption very well, but In Decryption I get an Exception: `&gt;&gt;java.security.InvalidKeyException: unknown key type passed to RSA`.
    

        KeyPairGenerator kpg;
    	KeyPair kp;
    	PublicKey publicKey;
    	PrivateKey privateKey;
    	byte [] encryptedBytes,decryptedBytes;
        Cipher cipher,cipher1;
        String encrypted,decrypted;
    
        public String RSAEncrypt (final String plain) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException 
        {
        	kpg = KeyPairGenerator.getInstance(&quot;RSA&quot;);
            kpg.initialize(1024);
            kp = kpg.genKeyPair();
            publicKey = kp.getPublic();
            privateKey = kp.getPrivate();
            
            cipher = Cipher.getInstance(&quot;RSA&quot;);
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            encryptedBytes = cipher.doFinal(plain.getBytes());
            encrypted = new String(encryptedBytes);
            System.out.println(&quot;EEncrypted?????&quot;+encrypted);
            return encrypted;
    
        }
    	
    	public String RSADecrypt (final String result) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException 
        {
    
            cipher1=Cipher.getInstance(&quot;RSA&quot;);
            cipher1.init(Cipher.DECRYPT_MODE, privateKey);
            decryptedBytes = cipher1.doFinal(result.getBytes());
            decrypted = new String(decryptedBytes);
            System.out.println(&quot;DDecrypted?????&quot;+decrypted);
            return decrypted;
    
        }
    
   

And I am calling the function from here:
    
    encrypt.setOnClickListener(new OnClickListener()
            { 
    			public void onClick(View arg0) 
    			{
    					try
    					{
    						RSAEncrypt rsaencrypt=new RSAEncrypt();
    						rsaencrypt.RSAEncrypt(name);
    						
    						result=rsaencrypt.RSAEncrypt(name);
    						Toast.makeText(getBaseContext(), result.toString(),Toast.LENGTH_SHORT).show();
    
    						System.out.println(&quot;Result:&quot;+result);
    					}
    					catch(Exception e)
    					{
    						e.printStackTrace();
    						Toast.makeText(getBaseContext(), e.toString(),Toast.LENGTH_LONG).show();
    					}
    			}
    		});
            
            decrypt.setOnClickListener(new OnClickListener()
            { 
    			public void onClick(View arg0) 
    			{
    				{
    					try
    					{
    						RSAEncrypt rsadecrypt=new RSAEncrypt();
    						
    						rsadecrypt.RSADecrypt(result);
    						
    					    ans=rsadecrypt.RSADecrypt(result);
    						System.out.println(&quot;Result is&quot;+ans);
    						Toast.makeText(getBaseContext(), ans.toString(),Toast.LENGTH_LONG).show();
    					}
    					catch(Exception e)
    					{
    						e.printStackTrace();
    						Toast.makeText(getBaseContext(), e.toString(),Toast.LENGTH_LONG).show();
    						System.out.println(&quot;Exception is&gt;&gt;&quot;+e);
    					}
    			}
    		});

RSA Encryption Decryption in Android

Where can i find some documentation on the format of an RSA public key?

An RSA public key formatted by `OpenSSH`:

&gt; ssh-rsa AAAAB3NzaC1yc2EAAAABJQAAAQB/nAmOjTmezNUDKYvEeIRf2YnwM9/uUG1d0BYsc8/tRtx+RGi7N2lUbp728MXGwdnL9od4cItzky/zVdLZE2cycOa18xBK9cOWmcKS0A8FYBxEQWJ/q9YVUgZbFKfYGaGQxsER+A0w/fX8ALuk78ktP31K69LcQgxIsl7rNzxsoOQKJ/CIxOGMMxczYTiEoLvQhapFQMs3FL96didKr/QbrfB1WT6s3838SEaXfgZvLef1YB2xmfhbT9OXFE3FXvh2UPBfN+ffE7iiayQf/2XR+8j4N4bW30DiPtOQLGUrH1y5X/rpNZNlWW2+jGIxqZtgWg7lTy3mXy5x836Sj/6L

The same public key formatted for use in Secure Shell [(RFC 4716 - The Secure Shell (SSH) Public Key File Format)][1]:

    ---- BEGIN SSH2 PUBLIC KEY ----
    AAAAB3NzaC1yc2EAAAABJQAAAQB/nAmOjTmezNUDKYvEeIRf2YnwM9/uUG1d0BYs
    c8/tRtx+RGi7N2lUbp728MXGwdnL9od4cItzky/zVdLZE2cycOa18xBK9cOWmcKS
    0A8FYBxEQWJ/q9YVUgZbFKfYGaGQxsER+A0w/fX8ALuk78ktP31K69LcQgxIsl7r
    NzxsoOQKJ/CIxOGMMxczYTiEoLvQhapFQMs3FL96didKr/QbrfB1WT6s3838SEaX
    fgZvLef1YB2xmfhbT9OXFE3FXvh2UPBfN+ffE7iiayQf/2XR+8j4N4bW30DiPtOQ
    LGUrH1y5X/rpNZNlWW2+jGIxqZtgWg7lTy3mXy5x836Sj/6L
    ---- END SSH2 PUBLIC KEY ----

The same public key formatted as an RSA public key (note the *five* **`-`**, and no space):

    -----BEGIN RSA PUBLIC KEY-----
    MIIBCgKCAQEA+xGZ/wcz9ugFpP07Nspo6U17l0YhFiFpxxU4pTk3Lifz9R3zsIsu
    ERwta7+fWIfxOo208ett/jhskiVodSEt3QBGh4XBipyWopKwZ93HHaDVZAALi/2A
    +xTBtWdEo7XGUujKDvC2/aZKukfjpOiUI8AhLAfjmlcD/UZ1QPh0mHsglRNCmpCw
    mwSXA9VNmhz+PiB+Dml4WWnKW/VHo2ujTXxq7+efMU4H2fny3Se3KYOsFPFGZ1TN
    QSYlFuShWrHPtiLmUdPoP6CV2mML1tk+l7DIIqXrQhLUKDACeM5roMx0kLhUWB8P
    +0uj1CNlNN4JRZlC7xFfqiMbFRU9Z4N6YwIDAQAB
    -----END RSA PUBLIC KEY-----

The hex dump of the base-64 encoded data:

    00 00 00 07 73 73 68 2d 72 73 61 00 00 00 01 25 00 00 01 00 7f 9c 09
    8e 8d 39 9e cc d5 03 29 8b c4 78 84 5f d9 89 f0 33 df ee 50 6d 5d d0 
    16 2c 73 cf ed 46 dc 7e 44 68 bb 37 69 54 6e 9e f6 f0 c5 c6 c1 d9 cb
    f6 87 78 70 8b 73 93 2f f3 55 d2 d9 13 67 32 70 e6 b5 f3 10 4a f5 c3 
    96 99 c2 92 d0 0f 05 60 1c 44 41 62 7f ab d6 15 52 06 5b 14 a7 d8 19 
    a1 90 c6 c1 11 f8 0d 30 fd f5 fc 00 bb a4 ef c9 2d 3f 7d 4a eb d2 dc 
    42 0c 48 b2 5e eb 37 3c 6c a0 e4 0a 27 f0 88 c4 e1 8c 33 17 33 61 38 
    84 a0 bb d0 85 aa 45 40 cb 37 14 bf 7a 76 27 4a af f4 1b ad f0 75 59 
    3e ac df cd fc 48 46 97 7e 06 6f 2d e7 f5 60 1d b1 99 f8 5b 4f d3 97 
    14 4d c5 5e f8 76 50 f0 5f 37 e7 df 13 b8 a2 6b 24 1f ff 65 d1 fb c8 
    f8 37 86 d6 df 40 e2 3e d3 90 2c 65 2b 1f 5c b9 5f fa e9 35 93 65 59 
    6d be 8c 62 31 a9 9b 60 5a 0e e5 4f 2d e6 5f 2e 71 f3 7e 92 8f fe 8b

i&#39;ve [read that there are a couple of formats][2]&lt;sup&gt;[&#128343;][3]&lt;/sup&gt;:

&gt; Key data may be encoded in three general ways:
&gt; 
&gt; -  Binary DER-encoded format. This is sometimes called ASN.1 BER-encoded
&gt; - PEM or base64 format. This is the same data as the DER-encoded file but it is encoded in base64 with additional header and footer lines
&gt; - XML format.

If it&#39;s [ASN.1][4], the hex certainly doesn&#39;t look like it.

What&#39;s the format of an RSA public key?

-----------

See also
--------

- [RSA Key Formats][2]
- [Abstract Syntax Notation One][4]
- [Convert Base64 Public Key to XML Signature][5] &lt;sup&gt;[&#128343;][6]&lt;/sup&gt;
- [Decode PEM formats][7]


  [1]: https://www.rfc-editor.org/rfc/rfc4716
  [2]: http://www.cryptosys.net/pki/rsakeyformats.html
  [3]: https://archive.fo/AnIlM
  [4]: http://en.wikipedia.org/wiki/Abstract_Syntax_Notation_One
  [5]: http://tools.ailon.org/tools/XmlKey
  [6]: https://archive.fo/mAYWx
  [7]: https://lapo.it/asn1js/

RSA Public Key format

I&#39;m using `crypto/rsa`, and trying to find a way to *properly* save and load a key. Is there a correct way to create a `[]byte` from an `rsa.PrivateKey`. If so, is there a way to properly do so for an `rsa.PublicKey`?

Thank you all very much.

Save and load crypto/rsa PrivateKey to and from the disk

Am I mistaken in thinking that the security of RSA encryption, in general, is limited by the amount of known prime numbers?

To crack (or create) a private key, one has to combine the right pair of prime numbers.

Is it impossible to publish a list of all the prime numbers in the range used by RSA? Or is that list sufficiently large to make this brute force attack unlikely? Wouldn&#39;t there be &quot;commonly used&quot; prime numbers?



Content Type	Original Author	Original Content on Stackoverflow
Question	Ajay kumar	View Question on Stackoverflow
Solution 1 - Cryptography	reto	View Answer on Stackoverflow
Solution 2 - Cryptography	Anders Lindahl	View Answer on Stackoverflow
Solution 3 - Cryptography	Ashish Singhal	View Answer on Stackoverflow

Digital signature for a file using openssl

Cryptography Problem Overview

Cryptography Solutions

Solution 1 - Cryptography

Solution 2 - Cryptography

Signing:

Verifying just the signature:

Verifying that the owner of the private key does vouch for `data.txt`:

Solution 3 - Cryptography

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Attributions

Cryptography Problem Overview

Cryptography Solutions

Solution 1 - Cryptography

Solution 2 - Cryptography

Signing:

Verifying just the signature:

Verifying that the owner of the private key does vouch for data.txt:

Solution 3 - Cryptography

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Oracle insert if not exists statement

Attributions

Verifying that the owner of the private key does vouch for `data.txt`: