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Status:

PROPOSED STANDARD

Authors:

S. Turner
J. Schaad

Stream:

IETF

Source:

smime (sec)

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DOI:  https://doi.org/10.17487/RFC5752

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Abstract

Cryptographic Message Syntax (CMS) SignedData includes the SignerInfostructure to convey per-signer information. SignedData supportsmultiple signers and multiple signature algorithms per signer withmultiple SignerInfo structures. If a signer attaches more than oneSignerInfo, there are concerns that an attacker could perform adowngrade attack by removing the SignerInfo(s) with the \'strong'algorithm(s). This document defines the multiple-signaturesattribute, its generation rules, and its processing rules to allowsigners to convey multiple SignerInfo objects while protecting againstdowngrade attacks. Additionally, this attribute may assist duringperiods of algorithm migration. [STANDARDS-TRACK]

For the definition ofStatus,seeRFC 2026.

For the definition ofStream, seeRFC 8729.