ee36a5c78b
- Add Params struct with Memory/Iterations/Parallelism/SaltLength/KeyLength - DefaultParams: OWASP 2024 baseline (m=64KiB, t=1, p=4, salt=16B, key=32B) — D-08 - TestParams: reduced cost (m=8KiB) so go test stays under 5s — D-26/Pitfall 4 - Hash(): crypto/rand salt per call, argon2.IDKey, PHC format $argon2id$v=19$... - Verify(): PHC split/parse, ErrInvalidHash on malformed, ErrIncompatibleVersion on v!=19 - subtle.ConstantTimeCompare for timing-attack resistance (T-2-13) - init() self-test: hash/verify round-trip panics on regression (D-08/T-2-15) - Add golang.org/x/crypto v0.51.0 as direct dependency
117 lines
3.7 KiB
Go
117 lines
3.7 KiB
Go
package auth
|
|
|
|
import (
|
|
"crypto/rand"
|
|
"crypto/subtle"
|
|
"encoding/base64"
|
|
"fmt"
|
|
"strings"
|
|
|
|
"golang.org/x/crypto/argon2"
|
|
)
|
|
|
|
// Params holds the argon2id cost parameters.
|
|
// The PHC string format self-describes these values, so each stored hash
|
|
// carries its own params — cost upgrades are non-breaking.
|
|
type Params struct {
|
|
Memory uint32 // KiB
|
|
Iterations uint32
|
|
Parallelism uint8
|
|
SaltLength uint32
|
|
KeyLength uint32
|
|
}
|
|
|
|
// DefaultParams matches the OWASP 2024 Password Storage Cheat Sheet baseline
|
|
// for argon2id (D-08). Do not reduce these in production.
|
|
var DefaultParams = Params{
|
|
Memory: 64 * 1024, // 64 MiB
|
|
Iterations: 1,
|
|
Parallelism: 4,
|
|
SaltLength: 16,
|
|
KeyLength: 32,
|
|
}
|
|
|
|
// TestParams uses reduced cost so that `go test` wall-time stays under 5 seconds
|
|
// (D-26, Pitfall 4). The same code path is exercised; only the cost differs.
|
|
var TestParams = Params{
|
|
Memory: 8 * 1024, // 8 MiB
|
|
Iterations: 1,
|
|
Parallelism: 2,
|
|
SaltLength: 16,
|
|
KeyLength: 32,
|
|
}
|
|
|
|
// init runs a self-test hash/verify round-trip to catch param-drift or build
|
|
// regressions at package import time (D-08).
|
|
func init() {
|
|
phc, err := Hash("self-test-password-12chars", TestParams)
|
|
if err != nil {
|
|
panic("argon2 self-test Hash failed: " + err.Error())
|
|
}
|
|
ok, err := Verify(phc, "self-test-password-12chars")
|
|
if err != nil || !ok {
|
|
panic("argon2 self-test Verify failed: hash/verify round-trip mismatch")
|
|
}
|
|
}
|
|
|
|
// Hash derives an argon2id key from password and encodes it as a PHC-formatted
|
|
// string. A fresh random salt is generated on every call (never reused).
|
|
//
|
|
// Length contract (D-25): callers MUST reject len(password) > 128 before calling
|
|
// Hash to prevent a long-password DoS. This function does not enforce the ceiling
|
|
// itself so that it remains a pure primitive usable in tests.
|
|
func Hash(password string, p Params) (string, error) {
|
|
salt := make([]byte, p.SaltLength)
|
|
if _, err := rand.Read(salt); err != nil {
|
|
return "", fmt.Errorf("auth: failed to generate salt: %w", err)
|
|
}
|
|
h := argon2.IDKey([]byte(password), salt, p.Iterations, p.Memory, p.Parallelism, p.KeyLength)
|
|
return fmt.Sprintf("$argon2id$v=%d$m=%d,t=%d,p=%d$%s$%s",
|
|
argon2.Version,
|
|
p.Memory,
|
|
p.Iterations,
|
|
p.Parallelism,
|
|
base64.RawStdEncoding.EncodeToString(salt),
|
|
base64.RawStdEncoding.EncodeToString(h),
|
|
), nil
|
|
}
|
|
|
|
// Verify checks whether password matches the argon2id PHC string encoded.
|
|
// Returns (true, nil) on match, (false, nil) on mismatch, and (false, sentinel)
|
|
// when encoded is structurally invalid or uses an incompatible argon2 version.
|
|
// The comparison is constant-time to prevent timing attacks (T-2-13).
|
|
func Verify(encoded, password string) (bool, error) {
|
|
parts := strings.Split(encoded, "$")
|
|
// A valid PHC string split on "$" yields 6 elements:
|
|
// [0]="" [1]="argon2id" [2]="v=19" [3]="m=...,t=...,p=..." [4]=<salt> [5]=<hash>
|
|
if len(parts) != 6 || parts[1] != "argon2id" {
|
|
return false, ErrInvalidHash
|
|
}
|
|
|
|
var version int
|
|
if _, err := fmt.Sscanf(parts[2], "v=%d", &version); err != nil {
|
|
return false, ErrInvalidHash
|
|
}
|
|
if version != argon2.Version {
|
|
return false, ErrIncompatibleVersion
|
|
}
|
|
|
|
var mem, iter uint32
|
|
var par uint8
|
|
if _, err := fmt.Sscanf(parts[3], "m=%d,t=%d,p=%d", &mem, &iter, &par); err != nil {
|
|
return false, ErrInvalidHash
|
|
}
|
|
|
|
salt, err := base64.RawStdEncoding.Strict().DecodeString(parts[4])
|
|
if err != nil {
|
|
return false, ErrInvalidHash
|
|
}
|
|
want, err := base64.RawStdEncoding.Strict().DecodeString(parts[5])
|
|
if err != nil {
|
|
return false, ErrInvalidHash
|
|
}
|
|
|
|
got := argon2.IDKey([]byte(password), salt, iter, mem, par, uint32(len(want)))
|
|
// NOTE: constant-time compare is required here to prevent timing attacks (T-2-13).
|
|
return subtle.ConstantTimeCompare(want, got) == 1, nil
|
|
}
|