Is RSA PKCS1-OAEP padding supported in bouncycastle?

Question

I'm implementing encryption code in Java/Android to match iOS encryption. In iOS there are encrypting with RSA using the following padding scheme: PKCS1-OAEP

However when I try to create Cipher with PKCS1-OAEP.

Cipher c = Cipher.getInstance("RSA/None/PKCS1-OAEP", "BC");

Below is the stacktrace

javax.crypto.NoSuchPaddingException: PKCS1-OAEP unavailable with RSA.
    at com.android.org.bouncycastle.jcajce.provider.asymmetric.rsa.CipherSpi.engineSetPadding(CipherSpi.java:240)
    at javax.crypto.Cipher.getCipher(Cipher.java:324)
    at javax.crypto.Cipher.getInstance(Cipher.java:237) 

Maybe this RSA/None/PKCS1-OAEP is incorrect? but can't find any definitive answer to say either PKCS1-OAEP is unsupported or the correct way to define it.

I'm using the spongycastle library so have full bouncycastle implementation.

Solution 1

The code in the first answer does work, but it's not recommended as it uses BouncyCastle internal classes, instead of JCA generic interfaces, making the code BouncyCastle specific. For example, it will make it difficult to switch to SunJCE provider.

Bouncy Castle as of version 1.50 supports following OAEP padding names.

• RSA/NONE/OAEPWithMD5AndMGF1Padding
• RSA/NONE/OAEPWithSHA1AndMGF1Padding
• RSA/NONE/OAEPWithSHA224AndMGF1Padding
• RSA/NONE/OAEPWithSHA256AndMGF1Padding
• RSA/NONE/OAEPWithSHA384AndMGF1Padding
• RSA/NONE/OAEPWithSHA512AndMGF1Padding

Then proper RSA-OAEP cipher initializations would look like

Cipher c = Cipher.getInstance("RSA/NONE/OAEPWithSHA1AndMGF1Padding", "BC");

Solution 2

The following code works, if anyone else is stuck with similar encryption encoding/padding issues

    SubjectPublicKeyInfo publicKeyInfo = new SubjectPublicKeyInfo(
            ASN1Sequence.getInstance(rsaPublicKey.getEncoded()));

    AsymmetricKeyParameter param = PublicKeyFactory
            .createKey(publicKeyInfo);
    AsymmetricBlockCipher cipher = new OAEPEncoding(new RSAEngine(),
            new SHA1Digest());
    cipher.init(true, param);

    return cipher.processBlock(stuffIWantEncrypted, 0, 32);

Comments

[vcsjones]

Without more detail it's hard to say, but it could be something like RSA/None/OAEPWithSHA1AndMGF1Padding, for example.

[Petr Prazak]

@vcsjones i see that noted on the following bouncycastle.org/wiki/display/JA1/Frequently+Asked+Questions but while that does get past the NoSuchPaddingException it isn;t the same padding as 'PKCS1-OAEP'. What additional detail would help?

[vcsjones]

OAEP uses some kind of hashing function, whether it's SHA1 or something else depends on the implementation. We need to know more about your iOS implementation. For example, if you used RSA_PKCS1_OAEP_PADDING in your RSA_public_encrypt function, that is SHA1 with MGF1. developer.apple.com/library/ios/#documentation/System/…. What does your iOS code look like?

[divanov]

Either from BouncyCastle documentation or another option by iterating a set returned by java.security.Provider.getServices().