How to Combine two Programming Languages: A Ruby and Golang Tutorial

During past projects, I experienced difficulties when developing with a Ruby encryption pack. Specifically, the project in question was a payment gateway and integration project for an Asian bank. They set up security requirements, one of which was the encryption of requests using 3DES-ECB. In the process of searching, I did not find a suitable Ruby library that would help me to create such a query. Сrypto pack is included in the basic Go library, but here 3DES was only in CBC mode. Then I had to resort to a non-standard solution, combining both languages. The Main Differences Between the ECB and the CBC In this encryption mode, the message is divided into blocks and each block is encrypted separately. Electronic codebook (ECB): The disadvantage of this system is that if your message contains 2 identical blocks, they will have the same encrypted output. This, unfortunately, does not hide data patterns well. Therefore, this method is not recommended for use in cryptographic protocols (Menezes, Alfred J.; van Oorschot, Paul C.; Vanstone, Scott A. (2018). Handbook of Applied Cryptography, p. 228.). Today, this method is vulnerable and lost its relevance. This method is good for those who want to know basic cryptographic algorithms. was invented in 1976. In CBC mode, each plaintext block is XORed with the previous ciphertext block before encryption. Cipher Block Chaining (CBC) Thus, each block of ciphertext depends on all blocks of plaintext processed up to that point. To make each message unique, an initialization vector should be used in the first block. Let's start writing the code. First, let's write a test: Let's create an acceptance test. Given: encryption key and text. First, we encrypt the text using the method and compare it to the decrypted text using the second method. tripleDesECBEncrypt tripleDesECBDecrypt ) encryptedText, err := tripleDesECBEncrypt(origtext, key) t.Fatal(err) } t.Fatal(error) } } //TripleDES // ./main_test.go package main import ( "fmt" "testing" "github.com/stretchr/testify/assert" func TestDesEncrypt (t *testing.T) { key := [] byte ( "123456789012345678901234" ) origtext := [] byte ( "VASIA MOSHN120049949123213" ) if err != nil { fmt.Printf( "%v\n" , encryptedText) // Let's see what the text turns into decrypted_text, error := tripleDesECBDecrypt([] byte (encryptedText), key) if error != nil { assert.Equal(t, string (origtext), string (decrypted_text)) To make the test work, we throw in the functions: } } } //TripleDES // ./main.go package main func main () { func tripleDesECBEncrypt (src, key [] byte ) ( string , error) { return "encrypt" , nil func tripleDesECBDecrypt (src, key [] byte ) ( string , error) { return "decrypt" , nil Initialize Dependency Management: $ go mod init tripleDES This command initializes and writes a new file in the current directory, effectively creating a new module rooted in the current directory. Next, you need to add dependencies to the module and sums: go.mod $ go mod tidy It adds any missing requirements to modules required to build packages and dependencies of the current module, and removes dependencies that are not used. Moreover, it includes all missing entries in and removes unnecessary ones. Also, this command is used to add dependencies, assembly combinations for different OS, architectures and tags. go.sum Editor's note regarding the above image: I have so many questions. Run test: Encrypt --- FAIL: TestDesEncrypt (0.00s) main_test.go:23: Error Trace: main_test.go:23 Error: Not equal: Diff: --- Expected +++ Actual @@ -1 +1 @@ -VASIA MOSHN120049949123213 +Decrypt Test: TestDesEncrypt FAIL FAIL tripleDES 0.350s $ go test expected: "VASIA MOSHN120049949123213" actual : "Decrypt" exit status 1 How tripleDES Works: DES and tripleDES uses the block length for encryption of 8 bytes or 64 bits. The text can be of any length and we need to add it so that we can divide it into blocks of 8 bytes. For this purpose, use PKCS5 Padding. The scheme is simple: Based on the remainder of the division, find out how many bytes are missing for an 8-byte division into blocks and include the so-called padding. Example: Let's assume that we have text VASIA MOSHN1200499491232133. The length of this text is 27 bytes. We need to get the remainder of the division 27% 8 = 3. To understand how many bytes are missing, we need to subtract the result of the remainder from 8 bytes 8 - 3 = 5. That is, the required insert is 5 bytes. Let's create 5 byte text, [5,5,5,5,5] and add it to the end of the text. Let's write the same in the form of code: } func PKCS5Padding (ciphertext [] byte , blockSize int ) [] byte { padding := blockSize - ( len (ciphertext)%blockSize) // Let's find out how many bytes are still missing. // padding := 8-(27%8) = 8-3 = 5 padtext := bytes.Repeat([] byte { byte (padding)}, padding) // Let's create text for the number of bytes that is not enough to divide by 8 // padtext := []byte{5,5,5,5,5} return append (ciphertext, padtext...) // Add it to the end of the text Surely, some readers will wonder why we are filling with the insert value, and not just creating a slice with zero or other values. The answer is simple, to get back the readable text, we need to know how many elements should be removed from the slice. Let's create this algorithm: } func PKCS5UnPadding (origData [] byte ) [] byte { length := len (origData) // Get the length of the slice unpadding := int (origData[length -1 ]) //Get the last element of the slice. It will tell us how many elements were added to the slice return origData[:(length - unpadding)] // Returning a slice without extra elements We will write the code in order to encrypt a new line: } } } } func tripleDesECBEncrypt (src, key [] byte ) ( string , error) { block, err := des.NewTripleDESCipher(key) // this divides our key into three parts of 8 bytes and creates subkeys from these, so if your key is not equal to 24 bytes, you will not succeed if err != nil { return "" , err bs := block.BlockSize() // Find out what block size origData := PKCS5Padding(src, bs) // Let's finalize our text so that it becomes valid for this encryption method if len (origData)%bs != 0 { return nil , errors.New( "Need a multiple of the blocksize" ) out := make ([] byte , len (origData)) // Let's create a slice to fill in encrypted data dst := out // We use this construction instead append for len (origData) > 0 { block.Encrypt(dst, origData[:bs]) // func Encrypt encrypts the origData block[:bs] in dst. origData = origData[bs:] // Decrease string length by block size dst = dst[bs:] // Decrease slice reference length by block size // Example with append // var out []byte // dst := make([]byte, bs) // iterationSteps := len(origData) / bs // for i := 0; i < iterationSteps; i++ { // block.Encrypt(dst, origData[:bs]) // origData = origData[bs:] // out = append(out, dst...) // } return out, nil For the test, we will decrypt the text: } } } } func tripleDesECBDecrypt (src, key [] byte ) ( string , error) { block, err := des.NewTripleDESCipher(key) // this divides our key into three parts of 8 bytes and creates subkeys from these, so if your key is not equal to 24 bytes, you will not succeed if err != nil { return nil , err bs := block.BlockSize() // Find out what block size if len (src)%bs != 0 { return nil , errors.New( "crypto/cipher: input not full blocks" ) out := make ([] byte , len (src)) // Make a slice to fill in the decrypted data dst := out // use this construction instead append for len (src) > 0 { block.Decrypt(dst, src[:bs]) // Decrypt decrypts the origData[:bs] block into dst. src = src[bs:] // Decrease the string length by the block size dst = dst[bs:] // Decrease slice length by block size out = PKCS5UnPadding(out) // Remove extra characters return out, nil We will use a binary file with parameters to call it from Ruby class. Let's prepare a file to build a binary file, using the flag pack, in order to easily transfer parameters to the executable file. ) flag.Parse() } fmt.Println(err) } } } } } } } Variant with } } } } } //TripleDES // ./main.go package main import ( "bytes" "crypto/des" "errors" "flag" "fmt" func main () { textForParse := flag.String( "text" , "" , "Text for parsing" ) key := flag.String( "key" , "" , "key for encrypt/decrypt" ) decrypt := flag.Bool( "d" , false , "Value for decrypt" ) var result [] byte var err error if *decrypt { result, err = tripleDesECBDecrypt([] byte (*textForParse), [] byte (*key)) } else { result, err = tripleDesECBEncrypt([] byte (*textForParse), [] byte (*key)) if err != nil { } else { fmt.Println( string (result)) func PKCS5Padding (ciphertext [] byte , blockSize int ) [] byte { padding := blockSize - ( len (ciphertext) % blockSize) // Find out how many bytes are still missing // padding := 8-(27%8) = 8-3 = 5 padtext := bytes.Repeat([] byte { byte (padding)}, padding) // Let's create text for the number of bytes that is not enough to divide by 8 // padtext := []byte{5,5,5,5,5} return append (ciphertext, padtext...) // Add it to the end of the text func PKCS5UnPadding (origData [] byte ) [] byte { length := len (origData) // Add it to the end of the text unpadding := int (origData[length -1 ]) // Get the last element of the slice. It will tell us how many elements were added to the slice return origData[:(length - unpadding)] // Returning a slice without extra elements func tripleDesECBEncrypt (src, key [] byte ) ( string , error) { block, err := des.NewTripleDESCipher(key) // Divides the key into three parts of 8 bytes and creates subkeys from these, so if your key is not equal to 24 bytes, you will not succeed if err != nil { return nil , err bs := block.BlockSize() // Let’s find out what block size origData := PKCS5Padding(src, bs) // Let's finalize our text so that it becomes valid for this encryption method if len (origData)%bs != 0 { return nil , errors.New( "need a multiple of the blocksize" ) out := make ([] byte , len (origData)) // Let's create a slice to fill in encrypted data dst := out // We use this construction instead of append for len (origData) > 0 { block.Encrypt(dst, origData[:bs]) //Decrypt decrypts the block origData[:bs] в dst. origData = origData[bs:] // Decrease the string length by the block size dst = dst[bs:] // Decrease slice reference length by block size append // var out []byte // dst := make([]byte, bs) // iterationSteps := len(origData) / bs // for i := 0; i < iterationSteps; i++ { // block.Encrypt(dst, origData[:bs]) // origData = origData[bs:] // out = append(out, dst...) // } return out, nil func tripleDesECBDecrypt (src, key [] byte ) ( string , error) { block, err := des.NewTripleDESCipher(key) // we divide the key into three parts of 8 bytes each and create subkeys from these, so if your key is not equal to 24 bytes, you will not succeed if err != nil { return nil , err bs := block.BlockSize() // Find out what block size if len (src)%bs != 0 { return nil , errors.New( "crypto/cipher: input not full blocks" ) out := make ([] byte , len (src)) // Let's create a slice to fill in the decrypted data dst := out // We use this construction instead of append for len (src) > 0 { block.Decrypt(dst, src[:bs]) // Decrypt decrypts the block origData[:bs] в dst. src = src[bs:] // Decrease the string length by the block size dst = dst[bs:] // Decrease slice length by block size out = PKCS5UnPadding(out) // Removing extra characters return out, nil Let's create a binary file: $ go build the triple-des file will appear in the root, you need to check it for work: $ ./triple-des -key=123456789012345678901234 -text= "VASIA MOSHN1200499491232133" # the answer will be an encrypted string # eb75f543d000bf93c8c634b5c638bc4b31912b30c899efd492102d95abfd4c84 Now let's decrypt the string: $ ./triple-des -key=123456789012345678901234 -text=eb75f543d000bf93c8c634b5c638bc4b31912b30c899efd492102d95abfd4c84 -d #VASIA MOSHN1200499491232133 The answer is the same as what we encrypted earlier. Now let's make it possible for the binary to run with ruby: And again, to begin with, we write tests: described_class.new(src, key).call RSpec.describe TripleDes::Encrypt do subject( :service ) do end let( :src ) { 'VASIA MOSHN1200499491232133' } let( :key ) { '123456789012345678901234' } context 'when text encrypted' do it 'return base64 string' do expect(service).to eql( 'eb75f543d000bf93c8c634b5c638bc4b31912b30c899efd492102d95abfd4c84' ) end end context 'when decode string' do let( :src ) { 'eb75f543d000bf93c8c634b5c638bc4b31912b30c899efd492102d95abfd4c84' } let( :service ) { `./triple-des -text=' #{src} ' -key=' #{key} ' -d` } it 'return decode string' do expect(service).to eql( "VASIA MOSHN1200499491232133" ) end end end The Class Itself: res = io.read.strip io.close res private module TripleDes class Encrypt def initialize (src, key) @src = src @key = key end def call io = IO.popen([ './triple-des' , "-text= #{src} " , "-key= #{key} " ]) end attr_reader: src, :key end end Let's check how it works: res = io.read.strip io.close res private described_class.new(src, key).call # frozen_string_literal: true require 'rspec/autorun' module TripleDes class Encrypt def initialize (src, key) @src = src @key = key end def call io = IO.popen([ './triple-des' , "-text= #{src} " , "-key= #{key} " ]) end attr_reader :src , :key end end RSpec.describe TripleDes::Encrypt do subject( :service ) do end let( :src ) { 'VASIA MOSHN1200499491232133' } let( :key ) { '123456789012345678901234' } context 'when text encrypted' do it 'return base64 string' do expect(service).to eql( 'eb75f543d000bf93c8c634b5c638bc4b31912b30c899efd492102d95abfd4c84' ) end end context 'when decode string' do let( :src ) { 'eb75f543d000bf93c8c634b5c638bc4b31912b30c899efd492102d95abfd4c84' } let( :service ) { `./triple-des -text=' #{src} ' -key=' #{key} ' -d` } it 'return decode string' do expect(service).to eql( "VASIA MOSHN1200499491232133\n" ) end end end .. 2 examples, 0 failures $ ruby ./triple-des.rb Finished in 0.01517 seconds (files took 0.08794 seconds to load) The repository with the code can be found here: https://github.com/sabunt/triple_des Conclusion The need to use the 3DES algorithm was determined by the requirements of the bank in which I worked at that time. There is an opinion that just because of the block size of 64 bits, this method is not safe and there are many ways to crack it. I think this is why this encryption method is not included in the standard libraries in Ruby and Go. To encrypt your data, I recommend using the AES algorithm, the block length of which is all 128 bits. To solve my problem, I had to use a non-standard method and combine the two languages. Such symbiosis is possible in other programming languages as well. Get creative and achieve your goals! Good luck!