Added function documentation for getRkpOperation

Author: subrahmanyaman

Applet/AndroidSEProviderLib/src/com/android/javacard/seprovider/KMSEProvider.java

@@ -539,7 +539,27 @@ KMOperation initSymmetricOperation(
       short ivStart,
       short ivLength,
       short macLength);
-  
+
+  /**
+   *  This function creates an Operation instance only for RKP module.
+   *
+   * @param purpose is KMType.ENCRYPT or KMType.DECRYPT for AES and DES algorithm. It will be
+   * KMType.SIGN and KMType.VERIFY for HMAC algorithm
+   * @param alg is KMType.HMAC, KMType.AES or KMType.DES.
+   * @param digest is KMType.SHA2_256 in case of HMAC else it will be KMType.DIGEST_NONE.
+   * @param padding is KMType.PADDING_NONE or KMType.PKCS7 (in case of AES and DES).
+   * @param blockMode is KMType.CTR, KMType.GCM. KMType.CBC or KMType.ECB for AES or DES else it is
+   * 0.
+   * @param keyBuf is aes, des or hmac key buffer.
+   * @param keyStart is the start of the key buffer.
+   * @param keyLength is the length of the key buffer.
+   * @param ivBuf is the iv buffer (in case on AES and DES algorithm without ECB mode)
+   * @param ivStart is the start of the iv buffer.
+   * @param ivLength is the length of the iv buffer. It will be zero in case of HMAC and AES/DES
+   * with ECB mode.
+   * @param macLength is the mac length in case of signing operation for hmac algorithm.
+   * @return KMOperation instance.
+   */
   KMOperation getRkpOperation(byte purpose,
       byte alg,
       byte digest,