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// Copyright © 2021 siddharth ravikumar <s@ricketyspace.net>
// SPDX-License-Identifier: ISC
package challenge
import (
"fmt"
"ricketyspace.net/cryptopals/lib"
)
func C15() {
ice := lib.StrToBytes("ICE ICE BABY")
fmt.Printf("ice: %v\n", ice)
padded_ice := lib.Pkcs7Padding(ice, 16)
fmt.Printf("ice padded: %v\n", padded_ice)
unpadded_ice, _ := lib.Pkcs7PaddingUndo(padded_ice)
for i := 0; i < len(ice); i++ {
if ice[i] != unpadded_ice[i] {
panic("padding undo failed!")
}
}
fmt.Printf("unpadded ice: %v\n", unpadded_ice)
// Will fail.
bad_ice := append(ice, []byte{5, 5, 5, 5}...)
fmt.Printf("bad ice: %v\n", bad_ice)
_, err := lib.Pkcs7PaddingUndo(bad_ice)
if err != nil {
fmt.Printf("bad ice upadding failed: %s\n", err.Error())
}
// Will fail.
evil_ice := append(ice, []byte{1, 2, 3, 4}...)
fmt.Printf("evil ice: %v\n", evil_ice)
_, err = lib.Pkcs7PaddingUndo(evil_ice)
if err != nil {
fmt.Printf("evil ice upadding failed: %s\n", err.Error())
}
}
// Output:
// ice: [73 67 69 32 73 67 69 32 66 65 66 89]
// ice padded: [73 67 69 32 73 67 69 32 66 65 66 89 4 4 4 4]
// unpadded ice: [73 67 69 32 73 67 69 32 66 65 66 89]
// bad ice: [73 67 69 32 73 67 69 32 66 65 66 89 5 5 5 5]
// bad ice upadding failed: input is not pkcs#7 padded
// evil ice: [73 67 69 32 73 67 69 32 66 65 66 89 1 2 3 4]
// evil ice upadding failed: input is not pkcs#7 padded
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