Thanks guys! really learning cool stuff.... I will take it from here and appreciate your time.
btw a interesting phenomenon where encrypting with the same key reveals the plaintext. echo -n 'deadbeef' > topsecret.txt xxd topsecret.txt 6465 6164 6265 6566 openssl enc -des-cbc -nosalt -nopad -K 0101010101010101 -iv 0000000000000000 -in topsecret.txt -out topsecret.bin xxd topsecret.bin 76bc d756 4077 8e6a openssl enc -des-cbc -nosalt -nopad -K 0101010101010101 -iv 0000000000000000 -in topsecret.bin -out topsecret.bin2 xxd topsecret.bin2 6465 6164 6265 6566 On Tue, Oct 29, 2013 at 4:27 PM, Viktor Dukhovni <openssl-us...@dukhovni.org > wrote: > On Tue, Oct 29, 2013 at 03:54:50PM +0100, Luis Rocha wrote: > > > The X.923 padding attaches to a complete message block another block of > > zeros: A = 00 00 00 00 00 00 00 00 > > I would expect the last padding byte to be 08, not 00, since 8 padding > bytes were added. PKCS#7 padding for the same complete block would be: > > 08 08 08 08 08 08 08 08 > > > $echo -n 'aaaaaaaa' > topsecret.txt > > $xxd topsecret.txt > > 6161 6161 6161 6161 > > > > Then encrypted it with a weak key and iv = 0. > > openssl enc -des-cbc -K 0101010101010101 -iv 0000000000000000 -nosalt -in > > topsecret.txt | xxd > > f90a ba97 690c af10 ea3b c77a e91d efe2 > > Which decrypts to: > > $ perl -e ' > $x="f90aba97690caf10ea3bc77ae91defe2"; > $x =~ s/(..)/chr(hex($1))/eg; print $x;' | > openssl enc -d -nopad -des-ecb -K 0101010101010101 | > od -tx1 > 0000000 61 61 61 61 61 61 61 61 f1 02 b2 9f 61 04 a7 > 18 > 0000020 > > which is what we expect, since XOR of 08 into each byte of the last block > yields the first block of ciphertext. > > > Made the same exercise in the tool: > > In the tool (GUI) using DES CBC mode with the same key '0101010101010101' > > the output is: > > F90A BA97 690C AF10 6161 6161 6161 6161 > > Well it is certainly rather unexpected, to say the least, for the > ciphertext of a full block to contain the plaintext as its second > block. OpenSSL is working correctly. Your CrypTool is not. Help > with using CrypTool is likely a topic for another list. > > -- > Viktor. > ______________________________________________________________________ > OpenSSL Project http://www.openssl.org > User Support Mailing List openssl-users@openssl.org > Automated List Manager majord...@openssl.org >
