Why Do My Go and Pycrypto AES-CFB Encryption Results Differ?

Discrepancy in AES-CFB Encryption Results between Go and Pycrypto

In an attempt to integrate a new Go application with an existing Python codebase, a user encounters discrepancies in the ciphertexts produced by the two languages. This disparity arises specifically in the implementation of AES-CFB encryption.

The issue stems from a difference in the CFB segment size used by each language. Pycrypto employs a segment size of 8 bits (CFB8), while Go does not offer native support for this configuration. As a result, the ciphertexts generated by Go and Pycrypto differ, rendering them mutually indecipherable.

Investigation of the Go code reveals that the CFBDecrypter and CFBEncrypter classes could potentially be adapted to support CFB8 by modifying the underlying source code. This approach would allow Go applications to seamlessly decrypt ciphertexts encrypted using Pycrypto's CFB8 settings.

Modified Go Code:

package main

import (
    "fmt"
    "crypto/cipher"
    "crypto/aes"
    "encoding/hex"
)

// encrypt
func main() {
    payload, err1 := hex.DecodeString("abababababababababababababababababababababababababababababababab")
    password, err2 := hex.DecodeString("0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF")
    iv, err3 := hex.DecodeString("00000000000000000000000000000000")

    if err1 != nil {
        fmt.Printf("error 1: %v", err1)
        return
    }

    if err2 != nil {
        fmt.Printf("error 2: %v", err2)
        return
    }

    if err3 != nil {
        fmt.Printf("error 3: %v", err3)
        return
    }

    aesBlock, err4 := aes.NewCipher(password)
    cfb8Decrypter := cipher.NewCFB8Decrypter(aesBlock, iv)
    cfb8Decrypter.XORKeyStream(payload, payload)

    fmt.Printf("%v\n", hex.EncodeToString(payload)) // should output dbf6b1877ba903330cb9cf0c4f530d40bf77fe2bf505820e993741c7f698ad6b
}

Conclusion:

By adapting Go's CFBDecrypter and CFBEncrypter classes to support CFB8, the user can ensure that Go applications can effectively decrypt ciphertexts encrypted using Pycrypto's AES-CFB8 settings, bridging the gap between the two languages and allowing for seamless integration between the Go application and the existing Python codebase.

The above is the detailed content of Why Do My Go and Pycrypto AES-CFB Encryption Results Differ?. For more information, please follow other related articles on the PHP Chinese website!