[kitten] DES enctypes are not PKCS#7 padded (Re: Input on Paul's concerns about aes-cbc)
Tom Yu <tlyu@MIT.EDU> Wed, 09 October 2013 13:12 UTC
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To: Luke Howard <lukeh@padl.com>
References: <20131009022305.BD1FB1A9E6@ld9781.wdf.sap.corp> <B1237751-AD3C-4A09-93DF-8CE56B746499@padl.com>
From: Tom Yu <tlyu@MIT.EDU>
Date: Wed, 09 Oct 2013 09:12:12 -0400
In-Reply-To: <B1237751-AD3C-4A09-93DF-8CE56B746499@padl.com> (Luke Howard's message of "Wed, 9 Oct 2013 13:34:26 +1100")
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Cc: "kitten@ietf.org" <kitten@ietf.org>, Sam Hartman <hartmans-ietf@mit.edu>
Subject: [kitten] DES enctypes are not PKCS#7 padded (Re: Input on Paul's concerns about aes-cbc)
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Luke Howard <lukeh@padl.com> writes: >> While I did write my code that calls SSPI's EncryptMessage() in 1999 >> (during W2K beta), and don't exactly remeber which documentation >> I used, The "MDSN Library October 2001 Platform SDK" contains >> a description titled "SSPI/Kerberos Interoperability with GSS-API >> with this code sample: > > Because this sample was geared towards GSS-API interoperability (which was DES only at the time, hence required PKCS#7 padding), it's no surprise that it correctly uses SECBUFFER_PADDING. The DES enctypes used in Kerberos are not PKCS#7 padding. When the plaintext is an exact multiple of the block size, there is no padding for DES. PKCS#7 type padding requires a full block of padding in that case, because it is self-describing. This could be an important distinction, but I haven't fully analyzed how this affects the usability of the AES-SHA2 proposal with SSPI EncryptMessage.
- [kitten] Input on Paul's concerns about aes-cbc Sam Hartman
- Re: [kitten] Input on Paul's concerns about aes-c… Greg Hudson
- Re: [kitten] Input on Paul's concerns about aes-c… Nico Williams
- Re: [kitten] Input on Paul's concerns about aes-c… Paul Miller (NT)
- Re: [kitten] Input on Paul's concerns about aes-c… Nico Williams
- Re: [kitten] Input on Paul's concerns about aes-c… Luke Howard
- Re: [kitten] Input on Paul's concerns about aes-c… Martin Rex
- Re: [kitten] Input on Paul's concerns about aes-c… Luke Howard
- [kitten] DES enctypes are not PKCS#7 padded (Re: … Tom Yu
- Re: [kitten] DES enctypes are not PKCS#7 padded (… Luke Howard
- Re: [kitten] DES enctypes are not PKCS#7 padded (… Tom Yu
- Re: [kitten] Input on Paul's concerns about aes-c… Luke Howard
- Re: [kitten] Input on Paul's concerns about aes-c… Tom Yu
- Re: [kitten] Input on Paul's concerns about aes-c… Benjamin Kaduk