I want to generate 512 bit RSA keypair and then encode my public key as a string. How can I achieve this?
- 5Warning: RSA 512 bit keys are completely insecure.Maarten Bodewes– Maarten Bodewes2019-02-13 01:22:06 +00:00Commented Feb 13, 2019 at 1:22
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1 Answer
For output as Hex-String
import java.security.*; public class Test { public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchProviderException { KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA"); keyGen.initialize(512); byte[] publicKey = keyGen.genKeyPair().getPublic().getEncoded(); StringBuffer retString = new StringBuffer(); for (int i = 0; i < publicKey.length; ++i) { retString.append(Integer.toHexString(0x0100 + (publicKey[i] & 0x00FF)).substring(1)); } System.out.println(retString); } } For output as byte values
import java.security.*; public class Test { public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchProviderException { KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA"); keyGen.initialize(512); byte[] publicKey = keyGen.genKeyPair().getPublic().getEncoded(); StringBuffer retString = new StringBuffer(); retString.append("["); for (int i = 0; i < publicKey.length; ++i) { retString.append(publicKey[i]); retString.append(", "); } retString = retString.delete(retString.length()-2,retString.length()); retString.append("]"); System.out.println(retString); //e.g. [48, 92, 48, .... , 0, 1] } } 
4 Comments
Angela
Thank you very much! If i should get result like this [48, -137, -97, 49, 13, 6, 8, 42, -122, 72, -122, -9, 13, 2, 3, 15 4, 0, 3, -132, -115, 0, 48, -127] should i use just toString method instead retString.append(Integer.toHexString(0x0100 + (publicKey[i] & 0x00FF)).substring(1)); ??
Yatin
If I want the output in PEM format then how do I do it?
vsapiha
to output as HEX the simpler solution is to use
javax.xml.bind.DatatypeConverter.printHexBinary(publicKey) @YatinGrover for PEM Base 64 you can use javax.xml.bind.DatatypeConverter.printBase64Binary(publicKey)