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116 lines
2.8 KiB
Go
116 lines
2.8 KiB
Go
// From: https://www.alexedwards.net/blog/how-to-hash-and-verify-passwords-with-argon2-in-go
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package argon2
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import (
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"crypto/rand"
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"crypto/subtle"
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"encoding/base64"
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"errors"
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"fmt"
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"strings"
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"golang.org/x/crypto/argon2"
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)
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type Params struct {
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memory uint32
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iterations uint32
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parallelism uint8
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saltLength uint32
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keyLength uint32
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}
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var DefaultParams = &Params{
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memory: 128 * 1024,
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iterations: 4,
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parallelism: 4,
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saltLength: 16,
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keyLength: 32,
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}
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func Hash(password string, p *Params) (encodedHash string, err error) {
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salt, err := generateRandomBytes(p.saltLength)
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if err != nil {
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return "", err
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}
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hash := argon2.IDKey([]byte(password), salt, p.iterations, p.memory, p.parallelism, p.keyLength)
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// Base64 encode the salt and hashed password.
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b64Salt := base64.RawStdEncoding.EncodeToString(salt)
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b64Hash := base64.RawStdEncoding.EncodeToString(hash)
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// Return a string using the standard encoded hash representation.
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encodedHash = fmt.Sprintf("$argon2id$v=%d$m=%d,t=%d,p=%d$%s$%s", argon2.Version, p.memory, p.iterations, p.parallelism, b64Salt, b64Hash)
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return encodedHash, nil
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}
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func Verify(password string, encodedHash string) (bool, error) {
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// Extract the parameters, salt and derived key from the encoded password
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// hash.
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p, salt, hash, err := decodeHash(encodedHash)
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if err != nil {
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return false, err
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}
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// Derive the key from the other password using the same parameters.
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otherHash := argon2.IDKey([]byte(password), salt, p.iterations, p.memory, p.parallelism, p.keyLength)
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// Check that the contents of the hashed passwords are identical. Note
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// that we are using the subtle.ConstantTimeCompare() function for this
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// to help prevent timing attacks.
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if subtle.ConstantTimeCompare(hash, otherHash) == 1 {
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return true, nil
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}
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return false, nil
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}
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func decodeHash(encodedHash string) (p *Params, salt, hash []byte, err error) {
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vals := strings.Split(encodedHash, "$")
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if len(vals) != 6 {
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return nil, nil, nil, errors.New("the encoded hash is not in the correct format")
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}
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var version int
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_, err = fmt.Sscanf(vals[2], "v=%d", &version)
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if err != nil {
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return nil, nil, nil, err
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}
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if version != argon2.Version {
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return nil, nil, nil, errors.New("incompatible version of argon2")
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}
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p = &Params{}
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_, err = fmt.Sscanf(vals[3], "m=%d,t=%d,p=%d", &p.memory, &p.iterations, &p.parallelism)
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if err != nil {
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return nil, nil, nil, err
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}
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salt, err = base64.RawStdEncoding.Strict().DecodeString(vals[4])
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if err != nil {
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return nil, nil, nil, err
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}
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p.saltLength = uint32(len(salt))
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hash, err = base64.RawStdEncoding.Strict().DecodeString(vals[5])
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if err != nil {
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return nil, nil, nil, err
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}
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p.keyLength = uint32(len(hash))
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return p, salt, hash, nil
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}
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func generateRandomBytes(n uint32) ([]byte, error) {
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b := make([]byte, n)
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_, err := rand.Read(b)
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if err != nil {
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return nil, err
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}
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return b, nil
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}
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