Added signer app

3 files changed, 226 insertions, 0 deletions

diff --git a/playground/cryptography.go b/playground/cryptography.go
new file mode 100644
index 0000000..6220683
--- /dev/null
+++ b/playground/cryptography.go
@@ -0,0 +1,136 @@
+package main
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/x509"
+	"encoding/asn1"
+	"encoding/base64"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+)
+
+const KeyBitSize = 4096
+
+func readFile(filename string) ([]byte, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	return ioutil.ReadAll(file)
+}
+
+func writeFile(filename string, data []byte) error {
+	file, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+
+	_, err = file.Write(data)
+	return err
+}
+
+func signData(data []byte, key *rsa.PublicKey) (string, error) {
+	based := base64.StdEncoding.EncodeToString(data)
+	h := sha256.Sum256([]byte(based))
+	dataHash := fmt.Sprintf("%x", h)
+
+
+	ciphertext, err := rsa.EncryptPKCS1v15(rand.Reader, key, []byte(dataHash))
+	if err != nil {
+		return "", err
+	}
+
+	signature := base64.StdEncoding.EncodeToString(ciphertext)
+	return fmt.Sprintf("%s.%s", based, signature), nil
+}
+
+func checkSignature(signedData string, key *rsa.PrivateKey) (bool, error) {
+	spl := strings.Split(signedData, ".")
+	data := spl[0]
+	signature := spl[1]
+
+	dataHash := fmt.Sprintf("%x", sha256.Sum256([]byte(data)))
+
+	decodedSign, err := base64.StdEncoding.DecodeString(signature)
+	if err != nil {
+		return false, err
+	}
+
+	signHash, err := decodeMessage(decodedSign, key)
+	if err != nil {
+		return false, err
+	}
+
+	return dataHash == string(signHash), nil
+}
+
+func encodeMessage(message []byte, key *rsa.PrivateKey) ([]byte, error) {
+	ciphertext, err := rsa.EncryptPKCS1v15(rand.Reader, &key.PublicKey, message)
+	if err != nil {
+		return nil, err
+	}
+	return ciphertext, nil
+}
+
+func decodeMessage(ciphertext []byte, key *rsa.PrivateKey) ([]byte, error) {
+	plaintext, err := rsa.DecryptPKCS1v15(rand.Reader, key, ciphertext)
+	if err != nil { return nil, err }
+	return plaintext, nil
+}
+
+func loadPublicPEM(filename string) (*rsa.PublicKey, error) {
+	pemBytes, err := readFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	block, _ := pem.Decode(pemBytes)
+	if block == nil {
+		return nil, errors.New("there is no key in file")
+	}
+
+	return x509.ParsePKCS1PublicKey(block.Bytes)
+}
+
+func loadPrivatePEM(filename string) (*rsa.PrivateKey, error) {
+	pemBytes, err := readFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	block, _ := pem.Decode(pemBytes)
+	if block == nil {
+		return nil, errors.New("there is no key in file")
+	}
+
+	return x509.ParsePKCS1PrivateKey(block.Bytes)
+}
+
+func generateKeys() (keys *rsa.PrivateKey, private []byte, public []byte, err error) {
+	key, err := rsa.GenerateKey(rand.Reader, KeyBitSize)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	var privateKey = &pem.Block{
+		Type: "PRIVATE KEY",
+		Bytes: x509.MarshalPKCS1PrivateKey(key),
+	}
+
+	asn1Bytes, _ := asn1.Marshal(key.PublicKey)
+	var publicKey = &pem.Block{
+		Type: "PUBLIC KEY",
+		Bytes: asn1Bytes,
+	}
+
+	bytePrivate := pem.EncodeToMemory(privateKey)
+	bytePublic := pem.EncodeToMemory(publicKey)
+	return key, bytePrivate, bytePublic, nil
+}
diff --git a/playground/go.mod b/playground/go.mod
new file mode 100644
index 0000000..7af8b27
--- /dev/null
+++ b/playground/go.mod
@@ -0,0 +1,3 @@
+module vasthecat.ru/playground
+
+go 1.16
diff --git a/playground/main.go b/playground/main.go
new file mode 100644
index 0000000..b8574f0
--- /dev/null
+++ b/playground/main.go
@@ -0,0 +1,87 @@
+package main
+
+import (
+    "fmt"
+    "os"
+)
+
+func runGeneration() {
+    _, privateBytes, publicBytes, err := generateKeys()
+    if err != nil {
+        fmt.Printf("Произошла ошибка при генерации ключей: %s\n", err)
+        os.Exit(1)
+    }
+
+    err = writeFile(os.Args[2], privateBytes)
+    if err != nil {
+        fmt.Printf("%s\n", err)
+        os.Exit(1)
+    }
+    err = writeFile(os.Args[3], publicBytes)
+    if err != nil {
+        fmt.Printf("%s\n", err)
+        os.Exit(1)
+    }
+}
+
+func runSign() {
+    keyFile := os.Args[2]
+    messageFile := os.Args[3]
+    resultFile := os.Args[4]
+
+    key, err := loadPublicPEM(keyFile)
+
+    message, err := readFile(messageFile)
+    if err != nil {
+        fmt.Printf("%s\n", err)
+        os.Exit(1)
+    }
+    signedMessage, err := signData(message, key)
+    if err != nil {
+        fmt.Printf("Произошла ошибка при подписи данных: %s\n", err)
+        os.Exit(1)
+    }
+    err = writeFile(resultFile, []byte(signedMessage))
+    if err != nil {
+        fmt.Printf("%s\n", err)
+        os.Exit(1)
+    }
+}
+
+func runCheck() {
+    keyFile := os.Args[2]
+    signedFile := os.Args[3]
+
+    key, err := loadPrivatePEM(keyFile)
+    if err != nil {
+        fmt.Printf("%s\n", err)
+        os.Exit(1)
+    }
+
+    data, err := readFile(signedFile)
+    if err != nil {
+        fmt.Printf("%s\n", err)
+        os.Exit(1)
+    }
+    result, err := checkSignature(string(data), key)
+    if err != nil {
+        fmt.Printf("%s\n", err)
+        os.Exit(1)
+    }
+
+    if result {
+        fmt.Println("Подпись верна")
+    } else {
+        fmt.Println("Подпись не верна")
+    }
+}
+
+func main() {
+    if os.Args[1] == "generate" {
+        runGeneration()
+    } else if os.Args[1] == "sign" {
+    	runSign()
+    } else if os.Args[1] == "check" {
+        runCheck()
+    }
+}