Error occurred while decoding OAEP padding

Question

While decrypting text using RSACryptoServiceProvider.Decrypt, I am getting the error:

Error occurred while decoding OAEP padding.

Answer 1

This error normally indicates you are using a public key to decrypt, while you should be using a private key for decryption. Give it a try.

Answer 2

I ran into this exact problem. UnicodeEncoding.GetBytes is not always the inverse of UnicodeEncoding.GetString.

byte[] a = new byte[32];

RandomNumberGenerator gen = new RNGCryptoServiceProvider();
gen.GetBytes(a);

UnicodeEncoding byteConverter = new UnicodeEncoding();

byte[] b = byteConverter.GetBytes(byteConverter.GetString(a));

//byte array 'a' and byte array 'b' will not always contain the same elements.

This is why RSACryptoServiceProvider.Decrypt fails. A lot of encrypt/decrypt examples on the web use Unicode encoding. Do not use Unicode encoding. Use Convert.FromBase64String and Convert.ToBase64String instead.

Answer 3

We were getting this issue when we were using the wrong key for decryption.

Answer 4

In my case the error has been caused by wrong padding settings.

Error: RSA decrypt: error:0407A079:rsa routines:RSA_padding_check_PKCS1_OAEP:oaep decoding error

I had openssl_public_encrypt() with OPENSSL_PKCS1_PADDING as a default value in PHP and keypair.decrypt() with the default value RSA_PKCS1_OAEP_PADDING in node-rsa.

So don't forget to check these options too.

Answer 5

Another thing to check: it was giving me this error, on the decrypt operation, as a result of forgetting to pass the public key into the RSACryptoServiceProvider for the encrypt operation.

Answer 6

FYI, you can still be (en/de)crypting in the right key sequence (encr:pub key, decr:priv key) - i.e. can still get this error decrypting with a private key - it just may be the wrong private key (i.e. from another cert/key pair), not the one paired w/ the pub key with which u encrypted initially. If u turn off OAEP padding and get a "bad data" exception, that's another indication.