xcrypto

Documentation

Overview

Package xcrypto provides cryptographic functions for HMAC-SHA256 operations.

This package offers a simplified interface for computing HMAC-SHA256 hashes, which are commonly used for:

• Message authentication
• API signature verification
• Token generation and validation
• Data integrity verification

Security Best Practices:

• Always use cryptographically secure random key generators (crypto/rand)
• Key length should be at least 32 bytes (256 bits) for HMAC-SHA256
• Never hardcode keys in source code
• Use timing-safe comparison when verifying HMAC values (use hmac.Equal)
• Rotate keys periodically in production systems

Index

• func HMACSHA256(key []byte, data []byte) []byte

Functions

func HMACSHA256

func HMACSHA256(key []byte, data []byte) []byte

HMACSHA256 computes a HMAC-SHA256 hash of the data using the provided key.

HMAC (Hash-based Message Authentication Code) provides both data integrity and authentication using a shared secret key. The SHA256 hash function produces a 32-byte (256-bit) output.

Parameters:

• key: The secret key for HMAC. Should be at least 32 bytes for security.
• data: The message data to authenticate. Can be empty.

Returns:

• []byte: The 32-byte HMAC-SHA256 digest.

The returned hash can be used for:

• Verifying data integrity
• Authenticating API requests
• Generating secure tokens

Example:

key := []byte("32-byte-secret-key-1234567890abcd")
data := []byte("message to authenticate")
mac := HMACSHA256(key, data)

// To verify later (timing-safe comparison):
expectedMAC := HMACSHA256(key, data)
if hmac.Equal(mac, expectedMAC) {
    // Valid
}

Note: For timing-safe verification, always use hmac.Equal() to compare HMAC values to prevent timing attacks.