draft-ietf-smime-cms-auth-enveloped-04.txt   draft-ietf-smime-cms-auth-enveloped-05.txt 
S/MIME Working Group R. Housley S/MIME Working Group R. Housley
Internet-Draft Vigil Security Internet-Draft Vigil Security
Updates: 3852 (if approved) September 2007
Cryptographic Message Syntax (CMS) Cryptographic Message Syntax (CMS)
Authenticated-Enveloped-Data Content Type Authenticated-Enveloped-Data Content Type
<draft-ietf-smime-cms-auth-enveloped-04.txt> <draft-ietf-smime-cms-auth-enveloped-05.txt>
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other Task Force (IETF), its areas, and its working groups. Note that other
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3. For each recipient, the encrypted content-authenticated- 3. For each recipient, the encrypted content-authenticated-
encryption key and other recipient-specific information are encryption key and other recipient-specific information are
collected into a RecipientInfo value, defined in Section 6.2 of collected into a RecipientInfo value, defined in Section 6.2 of
[CMS]. [CMS].
4. Any attributes that are to be authenticated but not encrypted 4. Any attributes that are to be authenticated but not encrypted
are collected in the authenticated attributes. are collected in the authenticated attributes.
5. The attributes collected in step 4 are authenticated and the 5. The attributes collected in step 4 are authenticated and the
content is authenticated and encrypted with the content- CMS content is authenticated and encrypted with the content-
authenticated-encryption key. If the authenticated encryption authenticated-encryption key. If the authenticated encryption
algorithm requires either the additional authenticated data (AAD) algorithm requires either the additional authenticated data (AAD)
or the content to be padded to a multiple of some block size, then or the content to be padded to a multiple of some block size, then
the padding is added as described in Section 6.3 of [CMS]. the padding is added as described in Section 6.3 of [CMS].
6. Any attributes that are to be provided without authentication 6. Any attributes that are to be provided without authentication
or encryption are collected in the unauthenticated attributes. or encryption are collected in the unauthenticated attributes.
7. The RecipientInfo values for all the recipients, the 7. The RecipientInfo values for all the recipients, the
authenticated attributes, then unauthenticated attributes, and the authenticated attributes, then unauthenticated attributes, and the
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generation of public/private key pairs relies on a random numbers. generation of public/private key pairs relies on a random numbers.
The use of inadequate pseudo-random number generators (PRNGs) to The use of inadequate pseudo-random number generators (PRNGs) to
generate cryptographic keys can result in little or no security. An generate cryptographic keys can result in little or no security. An
attacker may find it much easier to reproduce the PRNG environment attacker may find it much easier to reproduce the PRNG environment
that produced the keys, searching the resulting small set of that produced the keys, searching the resulting small set of
possibilities, rather than brute force searching the whole key space. possibilities, rather than brute force searching the whole key space.
The generation of quality random numbers is difficult. RFC 4086 The generation of quality random numbers is difficult. RFC 4086
[RANDOM] offers important guidance in this area. [RANDOM] offers important guidance in this area.
If the message-digest attribute is included in the AuthAttributes, If the message-digest attribute is included in the AuthAttributes,
then attribute value will contain the unencrypted one-way hash value then the attribute value will contain the unencrypted one-way hash
of the plaintext of the content. Disclosure of this hash value value of the plaintext of the content. Disclosure of this hash value
enables content tracking, and it can be used to determine if the enables content tracking, and it can be used to determine if the
plaintext matches one or more candidate contents. For these reasons, plaintext matches one or more candidate contents. For these reasons,
the AuthAttributes SHOULD NOT contain the message-digest attribute. the AuthAttributes SHOULD NOT contain the message-digest attribute.
4. IANA Considerations 4. IANA Considerations
None. None.
{{{ RFC Editor: Please remove this section prior to publication. }}} {{{ RFC Editor: Please remove this section prior to publication. }}}
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