디지털 서명: 암호화 John Hancock, Go Crypto 6

import (
    "crypto"
    "crypto/rand"
    "crypto/rsa"
    "crypto/sha256"
    "fmt"
)

func main() {
    // Let's create our special signing pen (RSA key pair)
    privateKey, err := rsa.GenerateKey(rand.Reader, 2048)
    if err != nil {
        panic("Oops! Our pen ran out of ink.")
    }
    publicKey := &privateKey.PublicKey

    // Our important message
    message := []byte("I solemnly swear that I am up to no good.")

    // Let's create a fingerprint of our message
    hash := sha256.Sum256(message)

    // Time to sign!
    signature, err := rsa.SignPKCS1v15(rand.Reader, privateKey, crypto.SHA256, hash[:])
    if err != nil {
        panic("Our hand cramped while signing!")
    }

    fmt.Printf("Our RSA signature: %x\n", signature)

    // Now, let's verify our signature
    err = rsa.VerifyPKCS1v15(publicKey, crypto.SHA256, hash[:], signature)
    if err != nil {
        fmt.Println("Uh-oh, someone forged our signature!")
    } else {
        fmt.Println("Signature checks out. Mischief managed!")
    }
}

import (
    "crypto/ecdsa"
    "crypto/elliptic"
    "crypto/rand"
    "crypto/sha256"
    "fmt"
    "math/big"
)

func main() {
    // Let's create our curvy signing pen
    privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
    if err != nil {
        panic("Our curvy pen got a bit too curvy!")
    }
    publicKey := &privateKey.PublicKey

    // Our important message
    message := []byte("Elliptic curves are mathematically delicious!")

    // Create a fingerprint of our message
    hash := sha256.Sum256(message)

    // Time to sign with our curvy pen!
    r, s, err := ecdsa.Sign(rand.Reader, privateKey, hash[:])
    if err != nil {
        panic("Our hand slipped while signing these curves!")
    }

    signature := append(r.Bytes(), s.Bytes()...)
    fmt.Printf("Our curvy ECDSA signature: %x\n", signature)

    // Let's verify our curvy signature
    r = new(big.Int).SetBytes(signature[:len(signature)/2])
    s = new(big.Int).SetBytes(signature[len(signature)/2:])
    valid := ecdsa.Verify(publicKey, hash[:], r, s)
    fmt.Printf("Is our curvy signature valid? %v\n", valid)
}

import (
    "crypto/ed25519"
    "crypto/rand"
    "fmt"
)

func main() {
    // Let's create our speedy signing pen
    publicKey, privateKey, err := ed25519.GenerateKey(rand.Reader)
    if err != nil {
        panic("Our speedy pen got a speeding ticket!")
    }

    // Our important message
    message := []byte("Speed is my middle name!")

    // Time to sign at lightning speed!
    signature := ed25519.Sign(privateKey, message)

    fmt.Printf("Our speedy Ed25519 signature: %x\n", signature)

    // Let's verify our speedy signature
    valid := ed25519.Verify(publicKey, message, signature)
    fmt.Printf("Is our speedy signature valid? %v\n", valid)
}