{ id-RSAES-OAEP,                           { sha384Identifier,                             mgf1SHA384Identifier,                             pSpecifiedEmptyIdentifier  }  }   rSAES-OAEP-SHA512-Identifier  AlgorithmIdentifier  ::=                        { id-RSAES-OAEP,                           { sha512Identifier,                             mgf1SHA512Identifier,                             pSpecifiedEmptyIdentifier  }  }   -- ===================   --   Main structures   -- ===================   -- Used in SubjectPublicKeyInfo of X.509 Certificate.   RSAPublicKey  ::=  SEQUENCE  {      modulus           INTEGER,    -- n      publicExponent    INTEGER  }  -- eHousley & Kaliski                                              [Page 17]INTERNET DRAFT                                             December 2002   -- AlgorithmIdentifier parameters for id-RSASSA-PSS.   -- Note that the tags in this Sequence are explicit.   RSASSA-PSS-params  ::=  SEQUENCE  {      hashAlgorithm     [0] HashAlgorithm DEFAULT                               sha1Identifier,      maskGenAlgorithm  [1] MaskGenAlgorithm DEFAULT                               mgf1SHA1Identifier,      saltLength        [2] INTEGER DEFAULT 20,      trailerField      [3] INTEGER DEFAULT 1  }   HashAlgorithm  ::=  AlgorithmIdentifier   MaskGenAlgorithm  ::=  AlgorithmIdentifier   -- AlgorithmIdentifier parameters for id-RSAES-OAEP.   -- Note that the tags in this Sequence are explicit.   RSAES-OAEP-params  ::=  SEQUENCE  {      hashFunc          [0] AlgorithmIdentifier DEFAULT                               sha1Identifier,      maskGenFunc       [1] AlgorithmIdentifier DEFAULT                               mgf1SHA1Identifier,      pSourceFunc       [2] AlgorithmIdentifier DEFAULT                               pSpecifiedEmptyIdentifier  }   END7  References   This section provides normative and informative references.7.1  Normative References   [P1v1.5]   Kaliski, B., "PKCS #1: RSA Encryption Version 1.5",              RFC 2313, March 1998.   [P1v2.1]   J. Jonsson, J., and B. Kaliski, "PKCS #1: RSA              Cryptography Specifications Version 2.1", Internet-Draft,              August 2002.  <draft-jonsson-pkcs1-v2dot1-00.txt>   [PROFILE]  Housley, R., Polk, W., Ford, W. and D. Solo, "Internet              X.509 Public Key Infrastructure: Certificate and CRL              Profile", RFC 3280, April 2002.Housley & Kaliski                                              [Page 18]INTERNET DRAFT                                             December 2002   [SHA2]     National Institute of Standards and Technology (NIST),              FIPS 180-2: Secure Hash Standard, 1 August 2002.   [STDWORDS] S. Bradner, "Key Words for Use in RFCs to Indicate              Requirement Levels", RFC 2119, March 1997.   [X.208-88] CCITT Recommendation X.208: Specification of Abstract              Syntax Notation One (ASN.1), 1988.   [X.209-88] CCITT Recommendation X.209: Specification of Basic              Encoding Rules for Abstract Syntax Notation One (ASN.1),              1988.   [X.509-88] CCITT Recommendation X.509: The Directory -              Authentication Framework.  1988.7.2  Informative References   [CMS]      Housley, R, "Cryptographic Message Syntax", RFC 3369,              August 2002.   [GUIDE]    National Institute of Standards and Technology,              Second Draft: "Key Management Guideline, Part 1:              General Guidance."  June 2002.              [http://csrc.nist.gov/encryption/kms/guideline-1.pdf]   [P1363a]   IEEE P1363 working group, IEEE P1363a D11: Standard              Specifications for Public Key Cryptography: Additional              Techniques, December 16, 2002              Available from http://grouper.ieee.org/groups/1363/.   [PKALGS]   Polk, W., Housley, R., and L. Bassham, "Algorithms and              Identifiers for the Internet X.509 Public Key              Infrastructure Certificate and Certificate Revocation              Lists (CRL) Profile", RFC 3279, April 2002.   [RANDOM]   Eastlake, D., Crocker, S. and J. Schiller, "Randomness              Recommendations for Security, RFC 1750, December 1994.8  Security Considerations   This specification supplements RFC 3280 [PROFILE].  The security   considerations section of that document applies to this specification   as well.   Implementations must protect the RSA private key.  Compromise of the   RSA private key may result in the disclosure of all messagesHousley & Kaliski                                              [Page 19]INTERNET DRAFT                                             December 2002   protected with that key.   The generation of RSA public/private key pairs relies on a random   numbers.  The use of inadequate pseudo-random number generators   (PRNGs) to generate cryptographic keys can result in little or no   security.  An attacker may find it much easier to reproduce the PRNG   environment that produced the keys, searching the resulting small set   of possibilities, rather than brute force searching the whole key   space.  The generation of quality random numbers is difficult.  RFC   1750 [RANDOM] offers important guidance in this area.   Generally, good cryptographic practice employs a given RSA key pair   in only one scheme.  This practice avoids the risk that vulnerability   in one scheme may compromise the security of the other, and may be   essential to maintain provable security.  While PKCS #1 Version 1.5   [P1v1.5] has been employed for both key transport and digital   signature without any known bad interactions, such a combined use of   an RSA key pair is not recommended in the future.  Therefore, an RSA   key pair used for RSASSA-PSS signature generation should not also be   used for other purposes.  For similar reasons, one RSA key pair   should always be used with the same RSASSA-PSS parameters.  Likewise,   an RSA key pair used for RSAES-OAEP key transport should not also be   used for other purposes.  For similar reasons, one RSA key pair   should always be used with the same RSAES-OAEP parameters.   This specification requires implementation to support the SHA-1 one-   way hash function for interoperability, but support for other one-way   hash function is permitted.  At the time of this writing, the best   (known) collision attacks against SHA-1 are generic attacks with   complexity 2^80, where 80 is one-half the bit length of the hash   value.  In general, when a one-way hash function is used with a   digital signature scheme, a collision attack is easily translated   into a signature forgery.  Therefore, the use of SHA-1 in a digital   signature scheme provides a security level of no more than 80 bits.   If a greater level of security is desired, then a secure one-way hash   function with a longer hash value is needed.  SHA-256, SHA-384, and   SHA-512 are reasonable choices [SHA2].   The metrics for choosing a one-way hash function for use in digital   signatures do not directly apply to the RSAES-OAEP key transport   algorithm, since a collision attack on the one-way hash function does   not directly translate into an attack on the key transport algorithm,   unless the encoding parameters P varies (in which case a collision   the hash value for different encoding parameters might be exploited).   Nevertheless, for consistency with the practice for digital signature   schemes, and in case the encoding parameters P is not the empty   string, it is recommended that the same rule of thumb be applied toHousley & Kaliski                                              [Page 20]INTERNET DRAFT                                             December 2002   selection of a one-way hash function for use with RSAES-OAEP.  That   is, the one-way hash function should be selected so that the bit   length of the hash value is at least twice as long as the desired   security level in bits.   This specification does not constrain the size of public keys or   their parameters for use in the Internet PKI.  However, the key size   selected impacts the strength achieved when implementing   cryptographic services.  Selection of appropriate key sizes is   critical to implementing appropriate security.  However, a 1024-bit   RSA public key and SHA-1 both provide a security level of about 80   bits.  In [GUIDE], the National Institute of Standards and Technology   (NIST) suggests that a security level of 80 bits is adequate for the   protection of sensitive information until 2015.  If a security level   greater than 80 bits is needed, then a longer RSA public key and a   secure one-way hash function with a longer hash value are needed.   Again, SHA-256, SHA-384, and SHA-512 are reasonable choices for such   a one-way hash function.  For this reason, the algorithm identifiers   for these one-way hash functions are included in the ASN.1 module in   section 5.   When using RSASSA-PSS, the same one-way hash function should be   employed for the hashAlgorithm and the maskGenAlgorithm, but it is   not required.  Using the same one-way hash function helps with   security analysis, and it reduces implementation complexity.   When using RSAES-OAEP, the same one-way hash function should be   employed for the hashFunc and the maskGenFunc, but it is not   required.  Using the same one-way hash function helps with security   analysis, and it reduces implementation complexity.9  IANA Considerations   Within the certificates and CRLs, algorithms are identified by object   identifiers.  All of the object identifiers used in this document   were assigned in Public-Key Cryptography Standards (PKCS) documents   or by the National Institute of Standards and Technology (NIST).  No   further action by the IANA is necessary for this document or any   anticipated updates.Housley & Kaliski                                              [Page 21]INTERNET DRAFT                                             December 200210  Author Addresses   Russell Housley   RSA Laboratories   918 Spring Knoll Drive   Herndon, VA 20170   USA   rhousley@rsasecurity.com   Burt Kaliski   RSA Laboratories   174 Middlesex Turnpike   Bedford, MA 01730   USA   bkaliski@rsasecurity.com11  Full Copyright Statement   Copyright (C) The Internet Society (2002). All Rights Reserved.   This document and translations of it may be copied and furnished to   others, and derivative works that comment on or otherwise explain it   or assist in its implementation may be prepared, copied, published   and distributed, in whole or in part, without restriction of any   kind, provided that the above copyright notice and this paragraph are   included on all such copies and derivative works.   In addition, the ASN.1 modules presented in Section 5 may be used in   whole or in part without inclusion of the copyright notice.  However,   this document itself may not be modified in any way, such as by   removing the copyright notice or references to the Internet Society   or other Internet organizations, except as needed for the purpose of   developing Internet standards in which case the procedures for   copyrights defined in the Internet Standards process shall be   followed, or as required to translate it into languages other than   English.   The limited permissions granted above are perpetual and will not be   revoked by the Internet Society or its successors or assigns. This   document and the information contained herein is provided on an "AS   IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK   FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT   LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL   NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY   OR FITNESS FOR A PARTICULAR PURPOSE.Housley & Kaliski                                              [Page 22]