Encryption is used to guarantee confidentiality. In case encryption MAY or MUST be used, one MUST use the block encryption algorithms identified by the following URI in conjunction with the use of XML Encryption
For asymmetric encryption, used to encrypt keys, the RSA algorithm in combination with OAEP padding and a SHA-1 digest MUST be used, as described at http://www.w3.org/TR/2002/REC-xmlenc-core-20021210/Overview.html#rsa-oaep-mgf1p. These algorithms are identified as