Easy Elliptic Curve Cryptography in Go

This package ties several other commonly used cryptography packages together. The goal is to make common cryptographic operations simple. It is based on secp256k1 cryptography, most famously used by Bitcoin.

This package was originally the part of https://github.com/regnull/ubikom, but then became its own little package, because why not.

Examples

Sign hash and verify signature:

	privateKey := NewPrivateKey(big.NewInt(12345))
	data := "super secret message"
	hash := Hash256([]byte(data))
	signature, err := privateKey.Sign(hash)
	if err != nil {
		log.Fatal(err)
	}
	publicKey := privateKey.PublicKey()
	success := signature.Verify(publicKey, hash)
	fmt.Printf("Signature verified: %v\n", success)
	// Output: Signature verified: true

Encrypt data so only the owner of the private key can decrypt it:

	aliceKey, err := NewRandomPrivateKey()
	if err != nil {
		log.Fatal(err)
	}
	bobKey, err := NewRandomPrivateKey()
	if err != nil {
		log.Fatal(err)
	}
	data := "super secret message"
	encrypted, err := aliceKey.Encrypt([]byte(data), bobKey.PublicKey())
	if err != nil {
		log.Fatal(err)
	}
	decrypted, err := bobKey.Decrypt(encrypted, aliceKey.PublicKey())
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s\n", string(decrypted))
	// Output: super secret message

Encrypt private key with passphrase:

	privateKey := NewPrivateKey(big.NewInt(12345))
	encryptedKey, err := privateKey.EncryptKeyWithPassphrase("my passphrase")
	if err != nil {
		log.Fatal(err)
	}
	decryptedKey, err := NewPrivateKeyFromEncryptedWithPassphrase(encryptedKey, "my passphrase")
	fmt.Printf("%d\n", decryptedKey.Secret())
	// Output: 12345

Convert public key to the serialized compressed representation:

	privateKey := NewPrivateKey(big.NewInt(12345))
	publicKey := privateKey.PublicKey()
	serializedCompressed := publicKey.SerializeCompressed()
	fmt.Printf("%x\n", serializedCompressed)
	publicKeyCopy, err := NewPublicFromSerializedCompressed(serializedCompressed)
	if err != nil {
		log.Fatal(err)
	}
	sameKey := publicKey.Equal(publicKeyCopy)
	fmt.Printf("the correct key was created: %v\n", sameKey)
	// Output: 03f01d6b9018ab421dd410404cb869072065522bf85734008f105cf385a023a80f
	// the correct key was created: true