PKCS#1 is one of the most used (de-facto) standard for real-world use of RSA.
That's for good reasons: PKCS#1 is well thought, versatile, understandable, has been relatively stable for over two decades, and remains practically secure in its original form, contrary to some other standardized uses¹ of RSA. The major upgrade to PKCS#1, from v1 to v2, circa 1998, introduced OAEP encryption with stronger security argument, and improved protection against timing and padding oracle attacks of a decryption device. V2.1 introduced PSS signature and multi-prime RSA.
PKCS#1² was updated from v2.1³ to v2.2⁴ in October 2012, and published by February 2013. Changes include:
- incorporation of erratas (last updated in 2005) to PKCS#1 v2.1 (last updated in 2002);
- additional hashes of the SHA-2 family, including SHA-512/256, SHA-224, and SHA-512/224;
- corresponding algorithm identifiers;
- corresponding test hex constants;
- availability only in PDF format with permission to copy disabled (but who automatically compares to test hex constants anyway?);
- updated legalese on the text (which remains worthless if taken literally, as it is of the form "permission to copy is granted if" followed by a condition that is false independently of what the copier does);
- in the ASN Module:
PKCS-1
was changed toPKCS-1v2-2
andpkcs-1(1)
was changed topkcs-1v2-2(2)
;- in the
IMPORTS
(..)FROM NIST-SHA2
section,modules(0) sha2(1)
was changed tohashAlgs(2)
.
What's the meaning, purposes and consequences of these changes in the ASN Module?
Are there any other technical changes? Is yes, which, and what's their meaning, purposes and consequences?
¹ The ISO/IEC 9796[-1] signature scheme was withdrawn for lack of security under chosen-message attack. The first scheme in ISO/IEC 9796-2 lives with a mild weakness under such condition. That's fixed with scheme 2, which is essentially PSS-R, and scheme 3 which is a variant functionally substitutable to the broken scheme 1.
² Archive page of the website for RSA Laboratories.
³ Copy as published by RSA Security Inc. Public-Key Cryptography Standards.
⁴ Copy as published by EMC Corporation Public-Key Cryptography Standards.