Please note: The code below is for exporting a private key. If you are looking to export the public key, please refer to my answer given here. The PEM format is simply the ASN.1 DER encoding of the key (per PKCS#1) converted to Base64. Given the limited number of fields needed to represent the key, … Read more
Your problem is at the beginning of the VerifyData method: public static bool VerifyData(string originalMessage, string signedMessage, RSAParameters publicKey) { bool success = false; using (var rsa = new RSACryptoServiceProvider()) { //Don’t do this, do the same as you did in SignData: //byte[] bytesToVerify = Convert.FromBase64String(originalMessage); var encoder = new UTF8Encoding(); byte[] bytesToVerify = encoder.GetBytes(originalMessage); … Read more
To Generate Private Key openssl genrsa -out privatekey.pem 2048 To Sign openssl dgst -sha256 -sign privatekey.pem -out data.txt.signature data.txt To Generate The Public Key dgst -verify requires the public key openssl rsa -in privatekey.pem -outform PEM -pubout -out publickey.pem To Verify openssl dgst -sha256 -verify publickey.pem -signature data.txt.signature data.txt In case of success: prints “Verified … Read more
PublicKey publicKey = KeyFactory.getInstance(“RSA”).generatePublic(new X509EncodedKeySpec(bytes)); For more info see this tutorial
I wanted to point out something as a response to a comment by ala asking if: Public Key = modulus + exponent That is exactly correct. There are a few ways of storing this exponent + modulus. The first attempt at a standard was in RFC 3447 (Public-Key Cryptography Standards (PKCS) #1: RSA Cryptography Specifications … Read more
Your teacher gave you: Public Key: (10142789312725007, 5) which means n = 10142789312725007 e = 5 where n is the modulus and e is the public exponent. In addition, you’re given Private Key: (10142789312725007, 8114231289041741) meaning that d = 8114231289041741 where d is the decryption exponent that should remain secret. You can “break” RSA by … Read more
Fundamentally different. SHA1 is a hash algorithm, which is a one way function, turning an input of any size into a fixed-length output (160 bit in this case). A cryptographic hash function is one for which it should not be possible to find two inputs giving the same output except by brute force (for instance, … Read more
The RSA algorithm can only encrypt data that has a maximum byte length of the RSA key length in bits divided with eight minus eleven padding bytes, i.e. number of maximum bytes = key length in bits / 8 – 11. So basicly you divide the key length with 8 -11(if you have padding). For … Read more
(Expanding more than I feel is appropriate for an edit.) PKCS1, available in several versions as rfcs 2313 2437 3447 and 8017, is primarily about using the RSA algorithm for cryptography including encrypting decrypting signing and verifying. But since crypto is often used between systems or at least programs it is convenient to have a … Read more
You need to convert your private key to PKCS8 format using following command: openssl pkcs8 -topk8 -inform PEM -outform DER -in private_key_file -nocrypt > pkcs8_key After this your java program can read it.