[VOIPSEC] S/MIME and SIP

[dennis]

Dear all,

According to page 208 of RFC3261,
"Some header fields must always have a plaintext
version because they
are required header fields in requests and responses -
these include:
To, From, Call-ID, CSeq, Contact."

The "inner" header is encrypted text, and "outer"
header is clear text.I thought that SIP proxy will
decrypt the "inner" header and use those "inner"
header information. And "outer" header does not have
any effect. 
Does anyone what the "outer" header exist for? 

Best regards,
Dennis 

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