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JEP 121: Stronger Algorithms for Password-Based Encryption

Summary​

Provide stronger Password-Based-Encryption (PBE) algorithm implementations in the SunJCE provider.

Non-Goals​

In addition to the algorithms listed in the Description section below, PKCS#5 defines several other encryption schemes for PBES2, many of them legacy, i.e., DES-CBC-PAD, DES-EDE3-CBC-PAD, RC2-CBC-PAD and RC5-CBC-PAD. Given the lack of demand for using these legacy encryption schemes with the newer Password-Based cryptography, e.g., PBES2, there is no plan to provide support for them.

Although the PKCS#11 spec defines some mechanisms for Password Based Cryptography, the SunPKCS11 provider currently does not support any of them. The support from the underlying PKCS11 library also seems minimal, e.g., Solaris softtoken impl supports only CKM_PBE_SHA1_RC4_128 and CKM_PKCS5_PBKD2. Thus, this JEP does not include the SunPKCS11 provider in its scope.

PKCS#5 v2.0 Amendment 1: XML Schema for Password-Based Cryptography defines the XML identifiers for the PBE algorithms defined in PKCS#5 v2.0, but this should be handled separately in XML code rather than in the SunJCE provider.

Motivation​

The currently supported PBE algorithms from the SunJCE provider only cover DESede, and RC2 (40-bit) with SHA1. To remain competitive we should also support PBE algorithm implementations with stronger cipher and message digest algorithms, such as AES cipher and SHA-2 family message digests, as well as those specified by PKCS#12.

Description​

PKCS#12 specifies the following PBE algorithms for its password-privacy mode:

  1. PBEwithSHA1AndRC4_128
  2. PBEwithSHA1AndRC4_40
  3. PBEwithSHA1AndDESede (3-key)
  4. PBEwithSHA1AndDESede (2-key)
  5. PBEwithSHA1AndRC2_128
  6. PBEwthSHA1AndRC2_40

We currently support only 3 and 6. To fully support PKCS12 keystores, we should add support for all the others.

There have also been demands for password-based cryptography algorithms using stronger encryption and digest schemes such as AES and SHA-2 family digests. Thus it we should add support for PBES2 and PBMAC1 (as defined in PKCS#5 v2.1) as recommended in PKCS#5 for newer applications.

The SunJCE provider will be enhanced to support the following algorithms:

  • PBEwithSHA1AndRC4_128 cipher
  • PBEwithSHA1AndRC4_40 cipher
  • PBEwithSHA1AndDESede (2-key) cipher
  • PBEwithSHA1AndRC2_128 cipher

and perhaps combinations of the PBES2 cipher algorithms registered using the algorithm name pattern PBEWith<prf>And<encryption> where

  • <prf> is one of HmacSHA1, HmacSHA224, HmacSHA256, HmacSHA384, or HmacSHA512, and

  • <encryption> is AES (i.e., AES-CBC-PAD in PKCS#5 v2.1 draft, AES with CBC mode and PKCS5Padding).

and finally, if time permits, to support for one or more of the following PBMAC1 mac algorithms:

  • PBEWithHmacSHA1 mac
  • PBEWithHmacSHA224 mac
  • PBEWithHmacSHA256 mac
  • PBEWithHmacSHA384 mac
  • PBEWithHmacSHA512 mac

Testing​

There are no test vectors provided in the PKCS#5 standard specification; we would have to check third-party providers and test against them to validate our own implementation.

Impact​

  • JCP: we should be able to support the new PBE algorithms without any API changes, however if any API changes are needed for PBMAC1 then they will be proposed for the Umbrella JSR.

  • Documentation: Need to update all relevant security whitepapers, the SunJCE provider documentation, and reference guides with the newly-supported PBE algorithms.