c# - How to properly verify data with rsa? -

i want sign message private key , verify public key, can't work..

here how sign data (edited, still not working):

public static string signdata(string message, string privatekey) {          byte[] plaintext = asciiencoding.unicode.getbytes(message);          var rsawrite = new rsacryptoserviceprovider();         rsawrite.fromxmlstring(privatekey);          byte[] signature = rsawrite.signdata(plaintext, new sha1cryptoserviceprovider());          return convert.tobase64string(signature);     } 

here how test data (edited, still not working):

public static bool verifydata(string sign, string publickey, string orig) {          byte[] signature = convert.frombase64string(sign);         byte[] original = asciiencoding.unicode.getbytes(orig);          var rsaread = new rsacryptoserviceprovider();         rsaread.fromxmlstring(publickey);          if (rsaread.verifydata(original, new sha1cryptoserviceprovider(), signature)) {             return true;         } else {             return false;         }     } 

i store keypair xml string inside account class. function executed in constructor of account.cs:

public void addkeys() {      rsacryptoserviceprovider provider = new rsacryptoserviceprovider(1024);      privatekey = provider.toxmlstring(true);     publickey = provider.toxmlstring(false); } 

i test overall thing this:

string signedhash = utility.signdata("test" ,account.privatekey);  if (utility.verifydata(signedhash, account.publickey, "test")) {               console.writeline("working!"); } else {     console.writeline("signing not working"); } 

why isn't overall thing working? guess doesn't work because of encoding stuff.

return asciiencoding.unicode.getstring(signature); 

the signature arbitrary binary data, isn't legal unicode/ucs-2. need use arbitrary encoding (https://en.wikipedia.org/wiki/binary-to-text_encoding#encoding_standards) encode of arbitrary data. popular transport signatures base64, you'd want

return convert.tobase64string(signature); 

and, of course, use convert.frombase64string in verify method.

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if you're compiling target of .net 4.6 or higher can make use of newer sign/verify api:

rsaread.verifydata(original, new sha1cryptoserviceprovider(), signature) 

would be

rsaread.verifydata(original, signature, hashalgorithmname.sha1, rsasignaturepadding.pkcs1) 

while might not simpler, prevents allocation , finalization of sha1cryptoserviceprovider other method did, , sets future when may want switch pkcs1 signature padding pss signature padding. (but real advantage method on rsa base class instead of rsacryptoserviceprovider specific type).