go-crypto

Go utilities for common cryptography tasks

Examples

Encrypt a large file with a public key and AES-256-CBC

package main

import (
    "crypto/rand"
    "crypto/rsa"
    "fmt"
    "github.com/phylake/go-crypto/cipher"
    "github.com/phylake/go-crypto/pki"
)

func main() {
    // use your own private key
    rsaKey, _ := pki.ParsePrivateKey([]byte(my768BitPrivateKey))

    // or generate one
    // rsaKey := generateKey()

    privateKey := pki.PrivateKey(*rsaKey)
    publicKey := pki.PublicKey(rsaKey.PublicKey)

    // the key used by AES-256-CBC. not your public key
    randomSymmetricKey := []byte("my secret 256 bit symmetric key ")

    // encrypt your unencrypted symmetric key with your public key
    encryptedRandomSymmetricKey, _ := publicKey.EncryptOAEP(randomSymmetricKey)

    // decrypt your encrypted symmetric key with your private key
    randomSymmetricKey2, _ := privateKey.DecryptOAEP(encryptedRandomSymmetricKey)
    fmt.Println(string(randomSymmetricKey2))

    superLargeFile := []byte("super large file contents")
    encryptedFile, _ := cipher.EncryptCBC(randomSymmetricKey, superLargeFile)

    // decrypt and print the original file
    superLargeFile2, _ := cipher.DecryptCBC(randomSymmetricKey, encryptedFile)

    fmt.Println(string(superLargeFile2))
}

func generateKey() *rsa.PrivateKey {
    rsaKey, err := rsa.GenerateKey(rand.Reader, 1024)
    if err != nil {
        panic(err)
    }
    return rsaKey
}

// checkout https://gist.github.com/phylake/7392335 for relevant OpenSSL commands
var my768BitPrivateKey string = `-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----`

Notable implementation details

• The only cipher used is 256 bit AES.