|Applies To||RSA BSAFE Crypto-C|
|Issue||How to use decrypt with 1024-bit modulus, 1024-bit private exponent and F4 public exponent but without CRT information|
|Resolution||The only "workaround" available is to use the private key masquerading as a public key. |
Basically, set a key object using KI_RSAPublic with the same modulus and set the private exponent to be the public exponent. Then, for example, to decrypt, use that "public" key with the B_Decrypt* functions.
This may take some experimentation - there is added complication if you are trying to decrypt data with OAEP. There is a workaround that will let you do a raw RSA decryption easily enough and the standard PKCS #1 v1.5 padding is easy to strip - but you may not be able to do this for OAEP.
In reality the CRT (Chinese Remainder Theorem) information is crucial performance-wise for private key operations and the real solution is for you to get the private key information from the source in a more appropriate format. If the private key is supplied as BER-encoded keys (KI_PKCS_RSAPrivateBER) to you then your procedure should be straight-forward.
|Legacy Article ID||a1344|