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PKI.encrypt(): missing padding block when last block is full #8

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hadley opened this issue Oct 6, 2014 · 2 comments
Closed

PKI.encrypt(): missing padding block when last block is full #8

hadley opened this issue Oct 6, 2014 · 2 comments

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@hadley
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hadley commented Oct 6, 2014 

key <- "abcdef"
ser <- serialize(list(x = 1), connection = NULL)

enc <- PKI::PKI.encrypt(ser, key, "AES-256")
dec <- PKI::PKI.decrypt(enc, key, "AES-256")

all.equal(ser, dec)
#> [1] "Lengths (80, 64) differ (comparison on first 64 components)"
all.equal(ser[1:64], dec)
#> [1] TRUE
@s-u s-u changed the title Decryption loses some trailing bytes? PKI.encrypt(): missing padding block when last block is full Oct 7, 2014
@s-u
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s-u commented Oct 7, 2014

This shows two bugs: first, the key is way too short (must be 32 bytes for AES-256) but it was not detected. second, when the payload is exactly multiple of the block size, the padding block was not generated, so decoding fails to finalize the last bock. So now this should work:

key <- PKI::PKI.digest("abcdef", "SHA256")
ser <- serialize(list(x = 1), connection = NULL)

enc <- PKI::PKI.encrypt(ser, key, "AES-256")
dec <- PKI::PKI.decrypt(enc, key, "AES-256")

all.equal(ser, dec)
#> [1] TRUE

@s-u s-u closed this as completed in 3412fef Oct 7, 2014
@hadley
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hadley commented Oct 7, 2014

Thanks!

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@hadley @s-u