Table of Content
- Understanding Argon2
- Implementation Framework
- Production Implementation
- Best Practices and Security Considerations
- Conclusion
Understanding Argon2
Being the winner in the Password Hashing Competition (PHC) for its better resistance to current attack vectors, Argon2 is the present gold standard for password hashing methods. Alex Biryukov, Daniel Dinu, and Dmitry Khovratovich created it in reaction to the changing threat environment for password security. The algorithm tackles basic flaws found in outdated hashing algorithms using creative design concepts that give memory-hardness and resistance to specialized hardware attacks.
This article provides best practices, security concerns, and practical implementations for implementing Argon2, especially in Go projects.
Major Benefits From Legacy Algorithms
Argon2 provides advancements above classical password hashing techniques like PBKDF2 and bcrypt:
Memory-Hardness: The main benefit of Argon2 is its high memory usage for hashing process. This trait makes large-scale attacks using specialized hardware (GPUs, ASICs) financially expensive since attackers have to supply considerable memory resources for parallel processing.
Customizable Settings: Depending on their particular infrastructure capabilities, the algorithm offers thorough control over security parameters, therefore enabling companies to balance security needs with performance limits.
Multi-Vector Attack Resistance: Argon2 is meant to resist several attack methods used by threat agents, including brute-force assaults, side-channel attacks, time-memory trade-offs, and more complex techniques.
Argon2 Variants
Argon2 comes in three different versions, each tailored for certain security needs:
Argon2d. Using data-dependent memory access designs, this variant optimized for maximum resistance against GPU-based attacks. This variant introduces computational dependencies that greatly prevent attempts at parallelization. But the data-dependent approach opens possible vulnerability to side-channel timing attacks. Best for controlled environment when side-channel attacks are not a concern (e.g: server password storage).
Argon2i. Using data-independent memory access designs, this variant put priority to avoid side-channel attack, but it is less resistant to GPU attack than Argon2d. This variant offers better defence against timing-based side-channel exploitations. Best for environment where possible attackers might see the hashing process (e.g: cryptocurrencies).
Argon2id. Hybrid method drawing on the best features of either version. First passes using Argon2i aim to avoid side-channel attacks; then change to Argon2d for improved GPU attack resistance. Most production environments are advised to use this variant as it offers balanced defense against many attack vectors.
Implementation Framework
Environment Setup
For Go, the recommended approach is utilizes the official extended cryptography library:
go get golang.org/x/crypto/argon2
This library offers a strong, well managed implementation, following cryptographic best practices.
Cryptographically Secure Salt
A crucial security feature that has to be properly applied is salt generation. Every password has to use a distinct, cryptographically safe salt to avoid rainbow table attacks and guarantee hash uniqueness even for same passwords.
Best Practices:
Choose cryptographically safe random number generators, as in
crypto/rand.Apply 16-byte (128-bit) minimum salt length.
Create distinct salts for every password process.
Don't use pseudorandom generators inappropriate for cryptographic (e.g.,
math/rand).
Parameters Configuration
Appropriate parameters value are critical for a balance of optimal security and performance. Important parameters needs detailed attention are:
Hash Length: The output hash size in bytes. Longer hashes offer more resistance to collisions. Most applications should use 32 bytes (256 bits); standard implementations range from 16 to 64 bytes.
Memory Cost: The memory usage in KiB (1024-byte units). Higher values improve security but increase resource usage. Typical enterprise setups span 32 MiB (32,768 KiB) to 1 GiB (1,048,576 KiB).
Time Cost: The iteration count. More iterations improve security but increase processing time. Standard practice use 1 to 10 iterations.
Parallelism The concurrent thread usage. Should usually based on the CPU core count on hand. 1, 2, 4, or 8 threads are typical configurations.
Tips: Aim for 250–500 millisecond hashing timing to balance user experience factors with security needs.
Production Implementation
Password Hashing Implementation
Argon2 typically follow the PHC String Format:
$argon2<variant>$v=<version>$m=<memory>,t=<iterations>,p=<parallelism>$<salt>$<hash>
Example:$argon2id$v=19$m=65536,t=3,p=4$G8NYSxrA+UMGHJbZVIXXXQ$UrHyBcYfCEms+92QVzGmfYqrWtH54WJY9FuROBQi/X8
Format Components:
argon2id: Algorithm variant identifierv=19: Argon2 versionm=65536,t=3,p=4: Parameter encoding (memory, time, parallelism)G8NYSxrA+UMGHJbZVIXXXQ: Base64-encoded saltUrHyBcYfCEms+92QVzGmfYqrWtH54WJY9FuROBQi/X8: Base64-encoded hash
package main
import (
"crypto/rand"
"encoding/base64"
"fmt"
"golang.org/x/crypto/argon2"
"log"
)
type Argon2Configuration struct {
HashRaw []byte
Salt []byte
TimeCost uint32
MemoryCost uint32
Threads uint8
KeyLength uint32
}
func generateCryptographicSalt(saltSize uint32) ([]byte, error) {
salt := make([]byte, saltSize)
_, err := rand.Read(salt)
if err != nil {
return nil, fmt.Errorf("salt generation failed: %w", err)
}
return salt, nil
}
func hashPasswordSecure(password string) (string, error) {
config := &Argon2Configuration{
TimeCost: 2,
MemoryCost: 64 * 1024,
Threads: 4,
KeyLength: 32,
}
salt, err := generateCryptographicSalt(16)
if err != nil {
return "", fmt.Errorf("password hashing failed: %w", err)
}
config.Salt = salt
// Execute Argon2id hashing algorithm
config.HashRaw = argon2.IDKey(
[]byte(password),
config.Salt,
config.TimeCost,
config.MemoryCost,
config.Threads,
config.KeyLength,
)
// Generate standardized hash format
encodedHash := fmt.Sprintf(
"$argon2id$v=%d$m=%d,t=%d,p=%d$%s$%s",
argon2.Version,
config.MemoryCost,
config.TimeCost,
config.Threads,
base64.RawStdEncoding.EncodeToString(config.Salt),
base64.RawStdEncoding.EncodeToString(config.HashRaw),
)
return encodedHash, nil
}
func main() {
hash, err := hashPasswordSecure("enterprise_secure_password")
if err != nil {
log.Fatal(err)
}
fmt.Println("Secure hash generated:", hash)
}
Password Verification Implementation
Password verification need to be well implementated to maintain security, while providing reliable authentication.
package main
import (
"crypto/subtle"
"encoding/base64"
"errors"
"fmt"
"golang.org/x/crypto/argon2"
"strings"
)
func parseArgon2Hash(encodedHash string) (*Argon2Configuration, error) {
components := strings.Split(encodedHash, "$")
if len(components) != 6 {
return nil, errors.New("invalid hash format structure")
}
// Validate algorithm identifier
if !strings.HasPrefix(components[1], "argon2id") {
return nil, errors.New("unsupported algorithm variant")
}
// Extract version information
var version int
fmt.Sscanf(components[2], "v=%d", &version)
// Parse configuration parameters
config := &Argon2Configuration{}
fmt.Sscanf(components[3], "m=%d,t=%d,p=%d",
&config.MemoryCost, &config.TimeCost, &config.Threads)
// Decode salt component
salt, err := base64.RawStdEncoding.DecodeString(components[4])
if err != nil {
return nil, fmt.Errorf("salt decoding failed: %w", err)
}
config.Salt = salt
// Decode hash component
hash, err := base64.RawStdEncoding.DecodeString(components[5])
if err != nil {
return nil, fmt.Errorf("hash decoding failed: %w", err)
}
config.HashRaw = hash
config.KeyLength = uint32(len(hash))
return config, nil
}
func verifyPasswordSecure(storedHash, providedPassword string) (bool, error) {
// Parse stored hash parameters
config, err := parseArgon2Hash(storedHash)
if err != nil {
return false, fmt.Errorf("hash parsing failed: %w", err)
}
// Generate hash using identical parameters
computedHash := argon2.IDKey(
[]byte(providedPassword),
config.Salt,
config.TimeCost,
config.MemoryCost,
config.Threads,
config.KeyLength,
)
// Perform constant-time comparison to prevent timing attacks
match := subtle.ConstantTimeCompare(config.HashRaw, computedHash) == 1
return match, nil
}
func authenticateUser(storedHash, password string) error {
isValid, err := verifyPasswordSecure(storedHash, password)
if err != nil {
return fmt.Errorf("authentication process failed: %w", err)
}
if !isValid {
return errors.New("authentication credentials invalid")
}
return nil
}
Testing the Implementation
Validation of cryptographic implementations depends on thorough testing.
package main_test
import (
"bytes"
"testing"
"golang.org/x/crypto/argon2"
)
func TestArgon2Consistency(t *testing.T) {
password := []byte("enterprise_test_password")
salt := []byte("standardized_salt_value")
// Standard parameters
timeCost := uint32(3)
memoryCost := uint32(64 * 1024)
threads := uint8(4)
keyLength := uint32(32)
// Generate multiple hashes with identical parameters
hash1 := argon2.IDKey(password, salt, timeCost, memoryCost, threads, keyLength)
hash2 := argon2.IDKey(password, salt, timeCost, memoryCost, threads, keyLength)
// Verify consistency
if !bytes.Equal(hash1, hash2) {
t.Error("Identical inputs produced inconsistent hashes")
}
// Verify uniqueness for different inputs
differentPassword := []byte("alternative_test_password")
hash3 := argon2.IDKey(differentPassword, salt, timeCost, memoryCost, threads, keyLength)
if bytes.Equal(hash1, hash3) {
t.Error("Different passwords produced identical hashes")
}
}
func TestArgon2EdgeCases(t *testing.T) {
salt := []byte("edge_case_testing_salt")
timeCost := uint32(1)
memoryCost := uint32(32 * 1024)
threads := uint8(2)
keyLength := uint32(32)
// Test empty password handling
emptyPassword := []byte("")
hash := argon2.IDKey(emptyPassword, salt, timeCost, memoryCost, threads, keyLength)
if len(hash) != int(keyLength) {
t.Error("Empty password handling failed")
}
// Test extended and special characters handling
extendedPassword := append(bytes.Repeat([]byte("x"), 1000), []byte("🙂🙃")...)
hash = argon2.IDKey(extendedPassword, salt, timeCost, memoryCost, threads, keyLength)
if len(hash) != int(keyLength) {
t.Error("Extended password handling failed")
}
// Verify parameter sensitivity
baseHash := argon2.IDKey([]byte("test_password"), salt, timeCost, memoryCost, threads, keyLength)
modifiedHash := argon2.IDKey([]byte("test_password"), salt, timeCost+1, memoryCost+1, threads+1, keyLength)
if bytes.Equal(baseHash, modifiedHash) {
t.Error("Parameter modification did not affect hash output")
}
}
Validation Needed
Consistency Testing. Check that the same inputs yield consistent results throughout several runs. Validate that various inputs produce different hash values.
Parameter Sensitivity. Guarantee that changes in parameters produce distinct hash outputs.
Edge Case Handling. Test limits with special character sets, maximum-length passwords, and zero passwords.
Standard Compliance. Validate against Argon2 official test vectors to guarantee specification compliance.
Best Practices and Security Considerations
Error Handling. Maintaining security also need to do correct error handling and gives suitable system feedback. Present generic authentication failure message e.g: Login Failed to users, it will help to avoid information leak. But log detailed technical errors for further issue analysis.
Use the encoded hash format. Avoid storing the parameters separately. The encoded hash string contains all needed data for password verification.
Benchmark on production hardware. Performance tuning has to be done in your real production setting. Parameters that work well on development computers might be unsuitable or ineffective in production.
Periodically parameter revision. Memory and time expenses should be modified as computing capability grows. When handling password verification is a good chance to modifie your hash parameters. You can simply re-hash the valid plain passwords with the new parameters.
Limit a sensible maximum password length. Unlike 72 bytes limit on bcrypt, Argon2 practically allows unlimited length of input. But permitting very long passwords could leave the system open to denial-of-service attacks. It's best to limit the password to a sensible length, usually 64 to 128 characters.
Utilize reliable libraries. Instead of implementing Argon2 by your own from scratch, depend on well-known, highly vetted libraries.
Test your implementation. Test against recognized input-output pairs to guarantee the robustness of your setup. Verify that invalid credentials are consistently rejected and that valid ones are authenticated properly. You can compare your implementation with available online generator or validator tools.
Conclusion
Providing strong defense against modern assault techniques, Argon2 is the current state-of-the-art in password hashing technology. Good execution calls for close focus on parameter configuration, coded language, and continuous security upkeep.
Argon2 should be used by companies giving top priority thorough testing, constant parameter review, and compliance with known cryptographic best practices. Good implementation investments offer substantial security advantages and show dedication to safeguarding user credentials against changing threat environments.
Top comments (1)
Good to know, nice article