114 lines
2.8 KiB
Go
114 lines
2.8 KiB
Go
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// cryptopasta - basic cryptography examples
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//
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// Written in 2015 by George Tankersley <george.tankersley@gmail.com>
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//
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// To the extent possible under law, the author(s) have dedicated all copyright
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// and related and neighboring rights to this software to the public domain
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// worldwide. This software is distributed without any warranty.
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//
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// You should have received a copy of the CC0 Public Domain Dedication along
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// with this software. If not, see // <http://creativecommons.org/publicdomain/zero/1.0/>.
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// Provides encoding and decoding routines for various cryptographic structures.
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package cryptopasta
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import (
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"crypto/ecdsa"
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"crypto/x509"
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"encoding/base64"
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"encoding/pem"
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"errors"
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"fmt"
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)
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// DecodePublicKey decodes a PEM-encoded ECDSA public key.
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func DecodePublicKey(encodedKey []byte) (*ecdsa.PublicKey, error) {
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block, _ := pem.Decode(encodedKey)
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if block == nil || block.Type != "PUBLIC KEY" {
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return nil, fmt.Errorf("marshal: could not decode PEM block type %s", block.Type)
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}
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pub, err := x509.ParsePKIXPublicKey(block.Bytes)
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if err != nil {
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return nil, err
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}
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ecdsaPub, ok := pub.(*ecdsa.PublicKey)
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if !ok {
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return nil, errors.New("marshal: data was not an ECDSA public key")
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}
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return ecdsaPub, nil
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}
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// EncodePublicKey encodes an ECDSA public key to PEM format.
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func EncodePublicKey(key *ecdsa.PublicKey) ([]byte, error) {
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derBytes, err := x509.MarshalPKIXPublicKey(key)
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if err != nil {
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return nil, err
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}
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block := &pem.Block{
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Type: "PUBLIC KEY",
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Bytes: derBytes,
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}
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return pem.EncodeToMemory(block), nil
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}
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// DecodePrivateKey decodes a PEM-encoded ECDSA private key.
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func DecodePrivateKey(encodedKey []byte) (*ecdsa.PrivateKey, error) {
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var skippedTypes []string
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var block *pem.Block
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for {
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block, encodedKey = pem.Decode(encodedKey)
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if block == nil {
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return nil, fmt.Errorf("failed to find EC PRIVATE KEY in PEM data after skipping types %v", skippedTypes)
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}
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if block.Type == "EC PRIVATE KEY" {
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break
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} else {
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skippedTypes = append(skippedTypes, block.Type)
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continue
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}
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}
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privKey, err := x509.ParseECPrivateKey(block.Bytes)
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if err != nil {
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return nil, err
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}
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return privKey, nil
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}
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// EncodePrivateKey encodes an ECDSA private key to PEM format.
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func EncodePrivateKey(key *ecdsa.PrivateKey) ([]byte, error) {
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derKey, err := x509.MarshalECPrivateKey(key)
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if err != nil {
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return nil, err
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}
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keyBlock := &pem.Block{
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Type: "EC PRIVATE KEY",
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Bytes: derKey,
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}
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return pem.EncodeToMemory(keyBlock), nil
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}
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// Encodes an ECDSA signature according to
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// https://tools.ietf.org/html/rfc7515#appendix-A.3.1
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func EncodeSignatureJWT(sig []byte) string {
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return base64.RawURLEncoding.EncodeToString(sig)
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}
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// Decodes an ECDSA signature according to
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// https://tools.ietf.org/html/rfc7515#appendix-A.3.1
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func DecodeSignatureJWT(b64sig string) ([]byte, error) {
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return base64.RawURLEncoding.DecodeString(b64sig)
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}
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