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Revise proposal 162: SHA256(x), not SHA256(SHA256(x))
The point of doing SHA256 twice is, generally, is to prevent message extension attacks where an attacker who knows H(A) can calculate H(A|B). But for attaching a signature to a document, the attacker already _knows_ A, so trying to keep them from calculating H(A|B) is pointless.
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@ -148,11 +148,10 @@ Spec modifications:
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4.1. The "sha256" signature format.
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The 'SHA256' signature format for directory objects is defined as
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the RSA signature of the OAEP+-padded SHA256 digest of the SHA256
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digest of the item to be signed. When checking signatures,
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the signature MUST be treated as valid if the signature material
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begins with SHA256(SHA256(document)); this allows us to add other
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data later.
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the RSA signature of the OAEP+-padded SHA256 digest of the item to
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be signed. When checking signatures, the signature MUST be treated
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as valid if the signature material begins with SHA256(document);
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this allows us to add other data later.
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Considerations:
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